Introduction Spectrometers

Introduction Fiber Optic Spectroscopy

Optical spectroscopy is a technique for measuring light intensity in the UV-, VIS-, NIR- and IR-region. Spectroscopic measurements are being used in many different applications, such as color measurement, concentration determination of chemical components or electromagnetic radiation analysis. For more elaborate application information and setups, please click on the Application link.

How does a spectrometer work

A spectroscopic instrument or spectrometer generally consists of entrance slit, collimator, a dispersive element, such as a grating or prism, focusing optics and detector. In a monochromator system there is normally also an exit slit, and only a narrow portion of the spectrum is projected on a one-element detector. In monochromators the entrance and exit slits are in a fixed position and can be changed in width. Rotating the grating scans the spectrum.

The development of micro-electronics during the 90’s in the field of multi-element optical detectors, such as Charged Coupled Devices (CCD) arrays and Photo-Diode (PD) arrays, enabled the production of low cost scanners, CCD cameras, etc. These same CCD and PDA detectors are now used in the Avantes AvaSpec line of spectrometers, enabling fast scanning of the spectrum, without the need for a moving grating.

Thanks to the need for fiber-optics in the communication technology, low absorption silica fibers have been developed. Similar fibers can be used as measurement fibers to transport light from the sample to the optical bench of the spectrometer. The easy coupling of fibers allows a modular build-up of a system that consists of light source, sampling accessories and fiber-optic spectrometer. Furthermore fiber-optic enable the introduction of sampling into harsh and difficult to access environments.

The low cost, modularity, flexibility and speed of measurement made possible by fiber-optic spectrometers have resulted in wide adoption of this technology in a variety of industries.

Optical Bench Design

The heart of most AvaSpec fiber-optic spectrometers is an optical bench with 37.5, 45, 50 or 75 mm focal length, developed in a symmetrical Czerny-Turner design. Light enters the optical bench through a standard SMA-905 connector and is collimated by a spherical mirror. A plain grating diffracts the collimated light; a second spherical mirror focuses the resulting diffracted light. An image of the spectrum is projected onto a 1-dimensional linear detector array.
optical bench
Avantes AvaSpec-HS1024x58/122 high-sensitivity spectrometers have a revolutionary new optical bench design with multiple toroid mirrors which ensure that the full numerical aperture of the fiber entrance will be projected on the backthinned CCD array.

All of our optical benches have a number of components installed inside, allowing a wide variety of different configurations, depending on the intended application. The choice of these components such as the diffraction grating, entrance slit, order-sorting filter, and detector coating have a strong influence on system specifications such as sensitivity, resolution, bandwidth and stray-light. Each of these specification is discussed in detail in the following paragraphs.

How to configure a spectrometer for your application

The modular AvaSpec line of instruments provides you with a number of configuration options to optimize the optical and spectroscopic performance of your instrument for your application.

This section provides you some guidance on how to choose the right grating, slit, detector and other configuration options, to be installed in your AvaSpec.

  • Wavelength Range
    In the determination of the optimal configuration of a spectrometer system the wavelength range is key parameter that defines the appropriate grating choice. If you are looking for a wide (broadband) wavelength range, we recommend the use of a 300 lines/mm grating known as an “A” type grating in Avantes product line. For lesser range (approximately 500 nm) but higher resolution, you might consider a 600 lines/mm or “B”-type grating. Higher lines/mm gratings (1200 – C type, 1800 – D type, 2400 – E type, 3600 – F type) provide higher resolution for applications that require this. Broadband gratings provide the greatest flexibility but may not provide the best performance for specific application. Contact an Avantes Sales Engineer or representative for a recommended grating configuration.
  • Detector choice
    The choice of your wavelength range along with the demands of your measurement speed and accuracy often suggests the appropriate detector for your application. Avantes offers 15 different detector types with each different sensitivity curves . The AvaSpec instrument line is divided into three groups based upon general requirements. The AvaSpec-Starline is comprised of general purpose UV/VIS instruments with low-cost CCD and PDA detectors. The AvaSpec Sensline is comprised of higher performance back-thinned CCDs and thermo-electrically cooled CCDs UV/VIS instruments. The instruments are particularly better in the UV and NIR relative to standard CCD detectors. The AvaSpec NIRLine is comprised of instruments with InGaAs arrays for longer wavelength measurements from 900-2500 nm.
    For high-speed applications, the 2048 pixel CCD detectors in the AvaSpec-ULS2048 and AvaSpec-ULS2048L from the StarLine are normally the best options. For VIS-only applications where high-resolution is not needed but speed and signal to noise are important, the 128 pixel PDA detector in the AvaSpec-128-USB2 may be the best option. For low-light level applications such as fluorescence and Raman, the SensLine instruments may be the most appropriate. The AvaSpec NIRLine features 7 different InGaAs detectors for various applications.
    The modularity and inter-compatibility of the AvaSpec line also make it possible to combine two or more detectors in a single instrument enclosure to provide optimal performance over a broad wavelength range. For example, an AvaSpec StarLine (UV/VIS) spectrometer can be combined with a NIRLine spectrometer to enable measurements from 200-2500 nm in a single instrument.
  • Optical Resolution & Slit Size
    If high optical resolution is required, you may want to consider a grating with higher lines/mm (1200- C type, 1800 – D type, 2400 – E type, 3600 – F type), thus limiting the range of the instrument to a more narrow range. Additionally, it is advisable to consider a detector with 2048 or 3648 pixels and a small slit (10 or 25 µm). For the best resolution with all other criteria of lesser importance, the AvaSpec-ULS3648 with a 10 micron slit is optimal. Slit size is a key factor in determining both resolution and throughput into the optical bench. It is important to balance your need for resolution with the need for sensitivity and throughput into the optical bench. If resolution is optimized without considering the need for throughput, you may not have adequate light to get a stable measurement. As previously mentioned, for optimal resolution our smallest slit (10 microns) is recommended. If your application does not require the highest possible resolution and is not one that has an excess of light (laser measurement for example), we recommend that you consider as large a slit as possible to maximize throughput into the optical bench.
    New is the AvaSpec-RS with replaceable slit that makes your spectrometer a versatile instrument for both high-resolution and high-sensitivity measurements.
  • Sensitivity
    When considering sensitivity, it is very important to distinguish between photometric sensitivity (How much light do I need for a detectable signal?) and chemometric sensitivity (What absorbance difference level can still be detected?)
    • Photometric Sensitivity
      For the best photometric sensitivity a combination of a high-throughput optical bench and a high quantum-efficiency (QE) detector is recommended. The instruments in the AvaSpec SensLine are specifically optimized for photometric sensitivity.
      For example fluorescence applications require high photometric sensitivity and Avantes AvaSpec-HS1024x122-TEC-USB2 is the highest performance instrument we offer for this application. For Raman applications where the combination of resolution and sensitivity is required, we recommend our AvaSpec-ULS2048L-USB2 spectrometer. To further enhance photometric sensitivity, we recommend the user of a detector collection lens (DCL-UV/VIS or DCL-UV/VIS-200), which is a cylindrical lens with focuses light from larger core fiber-optics and bundles down onto the smaller detector pixels.
      For additional photometric sensitivity, a larger slit or no slit and a 300 line/mm A-type grating to minimize light dispersion are available. Some more demanding applications also require thermo-electric cooling of the CCD detector (see product
      section AvaSpec-ULS2048LTEC and AvaSpec-ULS3648TEC) to minimize noise and increase dynamic range at long integration times (up to 60 seconds).
    • Chemometric Sensitivity
      To detect drastically different absorbance values, close to each other with maximum sensitivity, you need high Signal to Noise (S/N) performance. The detectors with best S/N performance are again in the AvaSpec SensLine series spectrometers with the AvaSpec-HS1024x122-TEC at the top of the line. The S/N performance can also be enhanced by averaging multiple spectra. The square root of the number of averages translates to the improvement in signal to noise.
  • Timing and Speed
    The data capture process is inherently faster with linear detector arrays and no moving parts as compared with a monochromator design, however, there are optimal detectors for each application. For high-speed applications such as measurements involving pulsed lasers and light sources, we recommend the AvaSpec-128-USB2, AvaSpec-ULS2048-USB2, AvaSpec-ULS2048L-USB2 or the AvaSpec-FAST spectrometers.
    Each of these instruments supports high- speed data acquisition with the capability of starting an acquisition within 1.3 microseconds of receiving an external trigger. The AvaSpec-FAST spectrometers can support integration times as low as 0.5 milliseconds, the AvaSpec-128-USB2 supports 0.06 milliseconds and the AvaSpec-ULS2048 and ULS2048L support 1.1 millisecond integration times. Since data transfer time is critical for these applications, Avantes’ unique Store-to-RAM mode enables on board storage of up to 5000 spectra to the instrument RAM buffer.
    The above parameters are the most important in choosing the right spectrometer configuration. Please contact our application engineers to optimize and fine-tune the system to your needs. The table on this page provides a quick reference guide for spectrometer selection for many common applications. The system recommendations in this table are for simple configurations of mostly single channel spectrometers.

Table 1 Quick reference guide for spectrometer configuration

Application

AvaSpec-type

Grating

WL range (nm)

Coating

Slit

FWHM Resolution (nm)

DCL

>OSF

OSC

Biomedical

ULS2048

NB

500-1000

-

50

1.2

-

475

-

Chemometry

ULS2048

UA

200-1100

-

50

2.0

-

-

OSC-UA

Color

128

VA

360-780

-

100

6.4

X/-

-

-

ULS2048

BB

360-780

-

200

4.1

X/-

-

-


Fluorescence

ULS2048XL

V, VB, UB

350-1100, 300-800

-

200

8.0

X

305

OSC

 HS1024x122TEC  HS-500-0.33 200-1160 - 200 10.0 - - OSC

Fruit-sugar

128

IA

800-1100

-

50

5.4

X

600

-

Gemology

ULS2048

VA

350-1100

-

25

1.4

X

-

OSC

High resolution

ULS2048

VD

600-700

-

10

0.07

-

550

-

ULS3648

VD

600-700

-

10

0.05

-

550

-

High UV/NIR-Sensitivity

HS1024x122TEC

HS-500-0.33

200-1160

-

200

10.0

-

-

OSC

Irradiance

ULS2048

UA

200-1100

DUV

50

2.8

X/-

-

OSC-UA

Laserdiode

ULS2048

NC

700-800

-

10

0.1

-

600

-

LED

ULS2048

VA

350-1100

-

25

1.4

X/-

-

OSC

LIBS

ULS2048

D, E, F

200-900

DUV

10

0.09

-

-

-

Raman

ULS2048LTEC

NC

780-930

-

25

0.2

X

600

-

Thin Films

ULS2048

UA

200-1100

DUV

-

4.1

X

-

OSC-UA

UV/VIS/NIR

ULS2048

UA

200-1100

DUV

25

1.4

X/-

-

OSC-UA

ULS2048XL

UA

200-1100

-

25

1.4

-

-

OSC-UA

NIR

 

NIR512-1.7TEC

NIR200-1.5

1000-1750

-

25

5.0

-

1000

-

NIR256-2.0TEC

NIR150-2.0

1000-2000

-

50

10.0

-

1000

-

NIR256-2.5TEC

NIR100-2.5

1000-2500

-

50

15.0

-

1000

OSC-NIR

How to choose the right grating?

A diffraction grating is an optical element that separates incident polychromatic radiation into its constituent wavelengths. A grating consists of series of equally spaced parallel grooves formed in a reflective coating deposited on a suitable substrate.

gratings.jpg

The way in which the grooves are formed separates gratings in two types, holo-graphic and ruled. The ruled gratings are physically formed onto a reflective surface with a diamond on a ruling machine. Gratings produced from laser constructed interference patterns and a photolithographic process are known as holographic gratings.

Avantes AvaSpec spectrometers come with a permanently installed grating that must be specified by the user. Additionally the user needs to indicate what wavelength range needs to reach the detector. Sometimes the specified usable range of a grating is larger than the range that can be projected on the detector. In order to cover a broader range, a dual or multi-channel spectrometer can be chosen. In this configuration each channel may have different gratings covering a segment of the range of interest. In addition to broader range, a dual or multi-channel spectrometer also affords higher resolution for each channel.

For each spectrometer type a grating selection table is shown in the spectrometer platform section. Table 2 illustrates how to read the grating selection table. The spectral range to select in Table 2 depends on the starting wavelength of the grating and the number of lines/mm; the higher the wavelength, the bigger the dispersion and the smaller the range to select.

Below the grating efficiency curves are shown. When looking at the grating efficiency curves, please realize that the total system efficiency will be a combination of fiber transmission, grating and mirror efficiency, detector quantum efficiency and coating sensitivities. The all new dual-blazed grating is a 300 lines/mm broadband grating (covering 200-1100 nm) that has optimized efficiency in both UV and NIR. On the bottom the grating dispersion curves are shown for the AvaSpec-ULS2048.

 

grating selection

Grating Efficiency Curves
300 lines/mm gratings
Grating 300
600 lines/mm gratings
Grating 600
1200 lines/mm gratings
Grating 1200
1800 lines/mm gratings
Grating 1800
2400 lines/mm gratings
Grating 2400
3600 lines/mm gratings
Gratings-Overview pag12
HS 500 lines/mm gratings
HS500
HS 830-1000 lines/mm gratings
HS830-1000
HS 1200 lines/mm gratings
HS 1200
NIR 100-200 lines/mm gratings
NIR 100-200
NIR 200-300 lines/mm gratings
NIR 200-300
NIR 300-400 lines/mm gratings
Grating overview NIR pag 13

 

Grating Dispersion Curves
300 lines/mm gratings
Avabench75 2048-pag14
600 lines/mm gratings
disp 600
1200 lines/mm gratings
disp 1200
1800 lines/mm gratings
disp 1800
2400 lines/mm gratings
disp 2400
3600 lines/mm gratings
disp 3600

How to select optimal Optical Resolution?

The optical resolution is defined as the minimum difference in wavelength that can be separated by the spectrometer. For separation of two spectral lines it is necessary to image them at least two array-pixels apart.

Because the grating determines how far different wavelengths are separated (dispersed) at the detector array, it is an important variable for the resolution. The other important parameter is the width of the light beam entering the spectrometer. This is basically the installed fixed entrance slit in the spectrometer, or the fiber core when no slit is installed.

For AvaSpec spectrometers the available slit widths are 10, 25, 50, 100, or 200 µm wide x 1000 µm high, or 500 µm wide x 2000 µm high. The slit image on the detector array for a given wavelength will cover a number of pixels. For two spectral lines to be separated, it is necessary that they be dispersed over at least this image size plus one pixel. When large core fibers are used the resolution can be improved by a slit of smaller size than the fiber core. This effectively reduces the width of the light beam entering the spectrometer optical bench.
The influence of the chosen grating and the effective width of the light beam (fiber core or entrance slit) are shown in the tables provided for each AvaSpec spectrometer instrument.

In the table below the typical resolution can be found for the AvaSpec-ULS2048. Please note that for the higher lines/mm gratings the pixel dispersion varies along the wavelength range and gets better towards the longer wavelengths.

The resolution in this table is defined as Full Width Half Maximum (FWHM), which is defined as the width in nm of the peak at 50% of the maximum intensity.

Graphs with information about the pixel dispersion can be found in the gratings section as well, so you can optimally determine the right grating and resolution for your specific application.

For larger pixel-height detectors (3648, 2048L, 2048XL) in combination with thick fibers (>200 µm) and a larger grating angle the actual FWHM value can be 10-20% higher than the value in the table. For best resolution small core diameter fibers are recommended.

All data in the resolution tables are based on averages of actual measured data (with 200 µm fibers) of our Quality Control System during the production process. A typical standard deviation of 10-25%, depending on the slit diameter and the grating should be taken into account. For 10 µm slits the typical standard deviation is somewhat higher, which is inherent to the laws of physics. The peak may fall exactly within one pixel, but may cover 2 pixels causing lower measured resolution.

New is the replaceable slit feature, available on all ULS spectrometers and the uncooled NIR 1.7 spectrometer. The spectrometers come with one installed slit and a slit kit which includes all four slit sizes, so you can opt for higher resolution (25 µm slit) or higher throughput (200 µm slit) or somewhere in between (50 or 100 µm slits).

 

Resolution (FWHM in nm) for the AvaSpec-ULS2048

Slit size (µm)

Grating (lines/mm)

10

25

50

100

200

500

300

0.80-0.90*

1.10-1.20*

2.30

4.60

9.00

22.0

600

0.40-0.50*

0.3.

1.15

2.31

4.50

11.0

830

0.28

0.40

0.80

1.60

3.20

8.0

1200

0.18-0.22*

0.29

0.61

1.18

2.20

5.5

1800

0.10-0.16*

0.19

0.35-0.42*

0.80

1.60

4.0

2400

0.08-0.11*

0.10-0.15*

0.28

0.55

1.10

2.8

3600

0.05-0.08*

0.10

0.18

0.38

0.75

1.9

*depends on the starting wavelength of the grating; the higher the wavelength, the bigger the dispersion and the higher the resolution

Detector arrays

The AvaSpec line of spectrometers can be equipped with several types of detector arrays. Presently we offer silicon-based CCDs, back-thinned CCDs, and Photo-Diode Arrays for the 200-1100 nm range. A complete overview of each is given in the next section “ Sensitivity “. For the NIR range (1000-2500 nm) InGaAs arrays are implemented.
All detectors are tested in incoming goods inspection, before they are used in our instruments. Avantes offers full traceability on following detector specifications:

• Dark noise
• Signal to noise
• Photo Response Non-Uniformity
• Hot pixels

StarLine CCD Detectors (AvaSpec-ULS2048/2048L/3648)

The Charged Coupled Device (CCD) detector stores the charge, dissipated as photons strike the photoactive surface. At the end of a controlled time-interval (integration time), the remaining charge is transferred to a buffer and then this signal is being transferred to the AD converter. CCD detectors are naturally integrating and therefore have enormous dynamic range, only limited by the dark (thermal) current and the speed of the AD converter. The 3648-pixel CCD has an integrated electronic shutter function, so an integration time of 10µs can be achieved.

+ Advantages for the CCD detectors are large numbers of pixels (2048 or 3648), high-sensitivity and high-speed.

-  Main disadvantage is the lower S/N ratio relative to other detector types.

 UV enhancement

For applications below 350 nm with the AvaSpec-ULS2048/2048L/3648 a special DUV-detector coating is required. The uncoated CCD-response below 350 nm is very poor; the DUV lumogen coating enhances the detector response in the region 150-350 nm. The DUV coating has a very fast decay time, typ. in ns range and is therefore useful for fast-trigger LIBS applications.

pagina 16 Starline detectoren vrijstaand

 

Photo Diode Arrays (AvaSpec-128)

A silicon photodiode array consists of a linear array of multiple photo-diode elements, for the AvaSpec-128 this is 128 pixels. Each pixel consists of a P/N junction with a positively doped P-region and a negatively doped N-region. When light enters the photodiode, electrons will become excited and generate an electrical signal. Most photodiode arrays have an integrated signal processing circuit with readout/integration amplifier on the same chip.

+  Advantages for the Photodiode detector are high NIR sensitivity and high-speed.

-  Disadvantages are limited amount of pixels and no UV-response.

pagina 16 Senseline detectoren vrijstaand

SensLine Back-thinned CCD Detectors (AvaSpec-ULS2048x16/x64/XL/HS1024x58/122)

For applications requiring high quantum efficiency in the UV (200-350 nm) and NIR (900-1160 nm) range, combined with good S/N and a wide dynamic-range, back-thinned CCD detectors are the right choice. Both uncooled and cooled backthinned CCD detectors are offered, the uncooled backthinned CCD detector has 2048 pixels with a pixel pitch of 14 µm and a height of 500 µm, to have more sensitivity and a better S/N performance.
For even better sensitivity and S/N the cooled backthinned CCD detector is the best choice, it has 1024 pixels, each of them with 58 or 122 vertically binned pixels, giving an effective detector height of 1.4 mm or nearly 3.0 mm

+  Advantage of the back-thinned CCD detector is the good UV and NIR sensitivity, combined with good S/N and dynamic range.

-  Disadvantage is the relatively higher cost.

pagina 16 Nirline detectoren vrijstaand

InGaAs linear image sensors (AvaSpec-NIR256/512)

The InGaAs linear image sensors deliver high-sensitivity in the NIR wavelength range. The detector consists of a charge- amplifier array with CMOS transistors, a shift-register and timing generator. For InGaAs detectors the dynamic range is limited by the dark noise. For ranges up to 1.75 µm no cooling is required and these detectors are available in both 256 and 512 pixels. Detectors for the extended range 2.0-2.5 µm all have 2- stage TE-cooling to reduce dark noise and are available in 256 and 512 pixel versions (1.7 and 2.2 detectors only).

7 versions of detectors are available:

  • 256 pixel non-cooled InGaAs detector for the 900-1750 nm range
  • 256/512 pixel cooled InGaAs detector for the 900-1750 nm range
  • 256 pixel 2-stage cooled Extended InGaAs detector for the 1000-2000 nm range
  • 256/512 pixel 2-stage cooled Extended InGaAs detector for the 1000-2200 nm range
  • 256 pixel 2-stage cooled Extended InGaAs detector for the 1000-2500 nm range

 

Sensitivity

The sensitivity of a detector pixel at a certain wavelength is defined as the detector electrical output per unit of radiation energy (photons) incident to that pixel. With a given A/D converter this can be expressed as the number of counts per mJ of incident radiation.
The relation between light energy entering the optical bench and the amount hitting a single detector pixel depends on the optical bench configuration. The efficiency curve of the grating used, the size of the input fiber or slit, the mirror performance and the use of a Detector Collection Lens are the main parameters. With a given set-up it is possible to do measurements over about 6-7 decades of irradiance levels. Some standard detector specifications can be found in Table 4 detector specifications. Optionally a DCL (Cylindrical Detector Collection) lens can be mounted directly on the detector array. The quartz lens (DCL-UV/VIS for AvaSpec-ULS2048/3648) will increase the system sensitivity by a factor of 3-5, depending on the fiber diameter used. The DCL-UV/VIS-200 can be used for the AvaSpec-ULS2048L/3648/2048XL to have a better vertical distribution of light focusing on the detector and is primarily for fiber diameters larger than 200 µm and round- to-linear assemblies.
The SensLine has the most sensitive detectors in Avantes’ instrument line, three backthinned detectors and two cooled CCD detectors.

In the tables below the UV/VIS detectors are depicted with their specifications, please find below some additional information on how those specifications are determined.

Pixel Well Depth (electrons)
This value is specified by the detector supplier and defines how many electrons can fit in a pixel well before it is saturated, this value determines the best reachable Signal to Noise (=√(Pixel well depth)).

Sensitivity in Photons/count @ 600 nm
The number of Photons of 600 nm that are needed to generate one count of signal on a 16-bit AD converter, the lower this number is, the better is the sensitivity of the detector. The calculation of the number of Photons/count is (Pixel Well depth in electrons)/16-bit AD/Quantum Efficiency @ 600 nm.

Sensitivity in counts/µW per ms integration time
Sensitivity here is for the detector types currently used in the UV/VIS AvaSpec spectrometers as output in counts per ms integration time for a 16-bit AD converter. To compare the different detector arrays we have them all built up with an optical bench with UA 300 lines/mm grating covering 200-1100 nm (AvaSpec-128 with grating VZ 350-1100 nm), DCL if applicable, and 50 µm slit. The measurement setup for 350-1100 nm has a 600 µm fiber connected to an AvaSpere-50-LS-HAL, equivalent to an optical power of 1.14 µW.For the UV/VIS measurement at 220-1100 nm we connected the 600 µm fiber to an AvaLight-DHS through a CC-VIS/NIR diffuser, equivalent to 2.7 µW power.

Peak wavelength and QE @ peak
The peak wavelength is provided by the detector supplier as well as the Quantum Efficiency, defined as the number of electrons generated by one photon.

Signal/Noise
Signal/Noise is measured for every detector at Avantes’ Quality Control Inspection and defined as the illuminated maximum Signal/Noise in Root Mean Square for the shortest integration time. The RMS is calculated over 100 scans.

Dark Noise
Dark noise is measured for every detector at Avantes’ Quality Control Inspection and defined as the non-illuminated noise in Root Mean Square for the shortest integration time. The RMS is calculated over 100 scans.

Dynamic Range
The dynamic range is defined as the (maximum signal level- baseline dark level)/dark noise RMS.

Photo Response Non-Uniformity
Photo Response Non-Uniformity is defined as the max difference between output of pixels when uniformly illuminated, divided by average signal of those pixels.
PRNU is measured for every detector at Avantes’ Quality Control Inspection.

Frequency
The frequency is the clock frequency at which the data pixels are clocked out through the AD-converter.

 

Detector Specifications (based on a 16-bit AD converter)

StarLine

Detector

TAOS 128

SONY2048

SONY2048L

TOS3648

Type

Photo diode array

CCD linear array

# Pixels, pitch

128, 63.5µm

2048, 14 µm

3648, 8 µm

Pixel width x height (µm)

55.5 x 63.5

14 x 56

14 x 200

8 x 200

Pixel well depth (electrons)

250,000

40,000

90,000

120,000

Sensitivity Photons/count @600nm

10

2 4

5

Sensitivity

in counts/µW per ms integration time

430,000 (AvaSpec-128)

310,000 (AvaSpec-ULS2048)

470,000 (AvaSpec-ULS2048L)

160,000

(AvaSpec-ULS3648)

Peak wavelength

750 nm

550 nm

450 nm

550 nm

QE (%) at peak 40%

Signal/Noise

500:1

200 :1

300 :1

350 :1

Dark noise (counts RMS)

15

33

20

34

Dynamic Range

4380

2000

3300

1900

PRNU**

± 4%

± 5%

Wavelength range (nm)

360-1100

200*-1100

Frequency

2 MHz

1 MHz

 

SensLine
 Detector

HAM2048x16

HAM2048x64

HAM2048XL

HAM1024x58 HAM1024x122
 Type

Back-thinned CCD array

 Back-thinned CCD array  Back-thinned CCD array  Cooled Back-Thinned CCD array Cooled Back-Thinned CCD array 
 # Pixels, pitch  2048x14, 14µm  2048x64, 14µm  2048, 14µm  1024 x 58, 24 µm 1024 x 122, 24 µm
 Pixel width x height (µm)  14 x 14  14 x 500  24 x 24 (total height 1.4 mm)  24 x 24 (total height 2.9 mm)
 Pixel well depth (electrons)  200,000  1,000,000
 Sensitivity Photons/count @600nm  4 16
Sensitivity

in counts/µW per ms integration time

 200,000 (AvaSpec-ULS2048x16)  600,000 (AvaSpec-ULS2048x64)  460,000 (AvaSpec-ULS2048XL)  850,000 (AvaSpec-HS1024x58) 1,270,000 (AvaSpec-HS1024x122)
 Peak wavelength  600 nm   650 nm
 QE (%) at peak  78%  92%
 Signal/Noise  500:1  500:1  450 :1  1000 :1  1000:1
 Dark noise (counts RMS)  17 8
 Dynamic Range   3800 8,000 
 PRNU**

±3%

 Wavelength range (nm)    200-1160  
 Frequency 1.33 MHz   1 MHz  250kHz  

 

* DUV coated

** Photo Response Non-Uniformity = max difference between output of pixels when uniformly illuminated, divided by average signal

Figure 5 Detector Spectral Sensitivity Curves

Sensitivity UV-VIS-NIR-2

sensitivity_uv-vis-nir.jpg



In the next table the specification is given for the NIR spectrometers, followed by the spectral response curve for the different detector types are depicted.

Sensitivity
For NIR detectors 2 different modes are available, the default setting is for high-sensitivity mode (HS), this means more signal at a shorter integration time. The other mode of operation is low-noise (LN), this means a better S/N performance.
Sensitivity, S/N, dark noise and Dynamic Range are given as HS and LN values.

NIR Detector Specifications

Detector NIR256-1.7 NIR256-1.7TEC NIR512-1.7TEC NIR256-2.0TEC NIR256-2.2TEC NIR512-2.2TEC NIR256-2.5TEC-HSC
Type Linear InGaAs array Linear InGaAs array with 2 stage TE cooling
# Pixels, pitch 256, 50 µm 512, 25 µm 256, 50 µm 512, 25 µm 256, 50 µm
Pixel width x height (µm) 50 x 500 25 x 500 50 x 250 50 x 500 25 x 500 50 x 250
Sensitivity HS
in counts/µW per ms
1,300,000 (integral 1000-1750 nm) 2,770,000 (integral 1000-1750 nm) 2,770,000 (integral 1000-1750 nm) 70,000 (integral 1000-2000 nm) 77,000 (integral 1200-2200 nm) 38,500 (integral 1200-2200 nm) 145,000 (integral 1000-2500 nm)
Signal/
Noise (HS)
2000:1 1700:1 1500:1 1200:1 1400 :1
Dark noise HS (counts RMS) 14 13 21 12 16
Dynamic Range HS

 

4000 5000 3300 4800 2800
Sensitivity LN
in counts/µW per ms
74,000 (integral 1000-1750 nm) 96,000 (integral 1000-1750 nm) 96,000 (integral 1000-1750 nm) 4,000 (integral 1000-2000 nm) 2,750 (integral 1200-2200 nm) 1,375 (integral 1200-2200 nm) 84,000 (integral 1000-2500 nm)
Signal/Noise (LN) 6000:1 3600:1 4000:1 4100:1 3685:1
Dark noise LN (counts RMS) 8 16 8 12
Dynamic Range LN 8000 4000 8000 3600
Peak wavelength 1550 nm 1500 nm 1850 nm 2000 nm 2300 nm
QE (%) @ peak 90% 70% 80% 60% 65%
PNRU** ± 5% 10% ± 5% 10% ±5%
Defective pixels (max) 0 12 5 10 12
Wavelength range (nm) 900-1750 1000-2000 1000-2200 1000-2500
Frequency 500 kHz 2.4 MHz 500 kHz 2.4 MHz 500 kHz

** Photo-Response Non-Uniformity

 

NIR Detector Sensitivity Curves

sensitivityCatIX NIR

Stray Light and second order effects

IMG 9831

Order Sorting Window in holder

Stray-light is radiation of undesired wavelengths that activates a signal at a detector element. Sources of stray-light can be:

  • Ambient light
  • Scattering light from imperfect optical components, or reflections of non-optical components
  • Order overlap

Avantes symmetrical Czerny-Turner optical bench designs favor stray-light rejection relative to crossed designs. Additionally, Avantes Ultra-Low Stray-light (AvaSpec-ULS) spectrometers have a number of internal measures to reduce stray-light from zero order and backscattering.

When working at the detection limit of the spectrometer system, the stray-light level from the optical bench, grating and focusing mirrors will determine the ultimate limit of detection. Most gratings used are holographic gratings, known for their low level of stray-light. Stray-light measurements are conducted using a halogen light source and long-pass or band-pass filters.

Typical stray-light performance for the AvaSpec-ULS and a B-type grating is <0.04% at 250-500 nm. Second order effects, which can play an important role for gratings with low groove frequency and therefore a wide wavelength range, are usually caused by the 2nd order diffracted beam of the grating. The effects of these higher orders can often be ignored, but sometimes need to be addressed using filtering. The strategy is to limit the light to the region of the spectra, where order overlap is not possible.

Second order effects can be filtered out, using a permanently installed long-pass optical filter in the SMA entrance connector or an order-sorting coating on a window in front of the detector. The order-sorting coatings on the window typically have one long-pass filter (600 nm) or 2 long-pass filters (350 nm and 600 nm), depending on the type and range of the selected grating.

In the table below a wide range of optical filters for installation in the optical bench can be found. The filter types that are 3 mm thick give much better 2nd order reduction than the 1 mm filters. The use of following long-pass filters is recommended: OSF-475-3 for grating NB and NC, OSF-515-3/550-3 for grating NB and OSF-600-3 for grating IB. For backthinned detectors, such as the 2048XL and 1024x58/122 we recommend an OSF-305 Filter, when the starting wavelength is 300 nm and higher.

In addition to the order-sorting coatings, we apply partial DUV coatings on the Sony 2048 detectors to avoid second-order effects from UV response and to enhance sensitivity and decrease noise in the visible range.

This partial DUV coating is done automatically for the following grating types:

  • UA for 200-1100 nm, DUV400, only first 400 pixels coated
  • UB for 200-700 nm, DUV800, only first 800 pixels coated

 Filters installed in AvaSpec spectrometer series

OSF-305-3

Permanently installed 3 mm order sorting filter @ 305 nm

OSF-385-3

Permanently installed 3 mm order sorting filter @ 385 nm

OSF-475-3

Permanently installed 3 mm order sorting filter @ 475 nm

OSF-515-3

Permanently installed 3 mm order sorting filter @ 515 nm

OSF-550-3

Permanently installed 3 mm order sorting filter @ 550 nm

OSF-600-3

Permanently installed 3 mm order sorting filter @ 600 nm

OSF-850-3

Permanently installed 3 mm order sorting filter @ 850 nm

OSC

Order sorting coating with 600 nm long pass filter for VA, BB (>350nm) and VB gratings in AvaSpec-ULS2048(L)/3648/2048x16/64/XL

OSC-UA

Order sorting coating with 350 and 600 nm long pass filter for UA gratings in AvaSpec-ULS2048(L)/3648/2048x16/64/XL

OSC-UB

Order sorting coating with 350 and 600 nm long pass filter for UB or BB (<350nm) gratings in AvaSpec-ULS2048(L)/3648/2048x16/64/XL

OSC-HS500

Order-sorting coating with 350 and 600 nm long-pass filter for HS500 gratings in AvaSpec-HS

OSC-HS900

Order-sorting coating with 600 nm long-pass filter for HS900 gratings in AvaSpec-HS

OSC-HS1000

Order-sorting coating with 350 nm long-pass filter for HS1000 gratings in AvaSpec-HS

OSC-NIR Order-sorting coating with 1400 nm long-pass filter for NIR100-2.5 and NIR150-2.0 gratings in AvaSpec-NIR256/512-2.2/2.5TEC

Thermal Stability

Thermal Stability

All AvaSpec spectrometers have no moving parts inside and are in nature extremely robust and stable.

The thermal stability of our spectrometers is part of our comprehensive Quality Control procedure and therefore closely monitored during the production and assembly process. All of our spectrometers undergo overnight thermal cycling, during which wavelength shift, intensity drop and spectral tilt are registered and checked against our QC acceptance norm.

More specifically, the following test are being carried out during the thermal cycling from 15°C to 25°C to 35°C back to 25°C:

Full Width Half Maximum

During the thermal cycling the average FWHM value is measured and has to fit with a certain standard deviation within the QC acceptance norm as can be found in this catalog for the different configurations.

Peakshift

During thermal cycling the shift of peaks is monitored and depicted as shift in pixels per °C.

Depending on the grating angle the maximum allowed peakshift is defined, for most gratings the below values are the QC acceptance norm. For gratings with many lines/mm starting at high wavelengths (VD, VE), the peak shift can double.

The max allowed peakshift =± 0.1 pixel per °C for an AvaSpec-ULS2048 with a pixel pitch of 14μm. Average peakshift is ± 0.04 pixel per °C for an AvaSpec-ULS2048

For an AvaSpec-ULS3648 with a pixel pitch of 8μm the max allowed peakshift is ± 0.17 pixel per °C.

For the AvaSpec-128 and for the AvaSpec-NIR256 with relative large pixels of 50μm the peakshift is limited to ± 0.03 pixel per °C.

For backthinned and NIR detectors with a 25μm pitch as in the AvaSpec-HS1024x58/122 and AvaSpec-NIR512 the peakshift is limited to ± 0.06 pixel per °C.

Intensity stability and Spectral tilt

Temperature sensitivity on the intensity axis can have a number of reasons. First the CCD detector itself has a temperature dependency, for most detectors there are black pixels that are read out and are subtracted from the rest of the data pixels, the so-called Correct for Dynamic dark (CDD). However, CDD will not correct for spectral tilt, which is partially also a detector property. The aluminum optical bench and the optical components are engineered in such a way that the thermal expansion does not lead to large increase in tilt or sensitivity.

For most spectrometers the average intensity increase/decrease is within ±4% for ± 10°C thermal cycling.

In the figure a typical test result for a thermal cycling can be seen.

Thermal-stability

Spectometer platforms

AvaSpec-2048L
Av
aSpec StarLine
The AvaSpec StarLine family of instruments is compromised of high-performance spectrometers which exceed the demands of most general spectroscopy applications. The StarLine includes high-speed instruments for process control (AvaSpec-128 and AvaSpec-FAST-series), high-resolution instruments for demanding measurements like atomic emission (AvaSpec-ULS3648) and versatile instruments for common applications such as irradiance and absorbance chemistry (AvaSpec-ULS2048 & Avaspec-ULS2048L). This instrument line offers an array of solutions for varied uses, while providing excellent price-to-performance ratios.

The AvaSpec-ULS2048/2048L and AvaSpec-3648 are based on front illuminated linear CCD arrays and thanks to Avantes’ DUV coating can measure wavelengths from 200-1100 nm. The AvaSpec-FAST series of instruments is specially designed for high-speed acquisitions such as pulsed light source and laser measurements. The AvaSpec-128 is an ultrafast photo-diode array-based instrument for visible and near-infrared applications.

Instruments in the AvaSpec StarLine family are designed to perform in a variety of applications such as:

  • Reflection and transmission measurements for optics, coatings, color measurement
  • Irradiance and emission measurements for environmental, light characterization, and optical emission spectroscopy
  • High-speed measurements for process control, LIBS or laser/pulsed source characterization
  • Absorbance chemistry


AvaSpec StarLine instruments are fully integrated with Avantes’ modular platform, allowing them to function stand-alone, or as multi-channel instruments. These products are fully compatible with other AvaSpec instruments in our AvaSpec SensLine and NIRLine. The entire AvaSpec StarLine is available as an individual lab instrument or an OEM module for integration into a customers’ existing system.

The StarLine instruments are available with our standard AvaBench-45 optical bench (45 mm focal length) or the Ultra-Low Stray-light (ULS) optical bench (75 mm focal length). The AvaSpec StarLine instruments are also available with a number of premium options such as irradiance/intensity calibration and non-linearity calibration.

AvaSpec-2048xl-2
AvaSpec SensLine

The AvaSpec SensLine family of products is Avantes’ response to customers who require higher performance for deman-ding spectroscopy applications such as fluorescence, luminescence and Raman. The AvaSpec SensLine product line includes five high-sensitivity, low-noise spectrometers. Three of the instruments are based on back-thinned detector technology, of which two feature high-performance thermoelectrically cooled detectors. The other two models are based on standard CCDs, upgraded to high-performing instruments as a result of Avantes’ unique and recently improved detector cooling technology. The back-thinned CCD detectors featured in the AvaSpec SensLine product family are high quantum efficiency detectors with excellent response in the UV, VIS and NIR from 200-1160 nm.

AvaSpec SensLine instruments are fully integrated with Avantes’ modular platform, allowing them to function standalone, or as multi-channel instruments. These products are fully compatible with other AvaSpec instruments in our AvaSpec StarLine and AvaSpec NIRLine product families. The entire AvaSpec SensLine is available as a lab instrument or an OEM module for integration into a customers’ existing system.Avantes’ innovative ultra-low stray-light (ULS) and revolutionary new High-Sensitivity (HS) optical benches are the core optical technologies in the AvaSpec SensLine. These highly stable optical benches combined with our high-performance AS5216-USB2 electronics board deliver high-performance instruments at affordable prices.

All members of the AvaSpec SensLine are designed to provide performance features such as:

  • High-stability
  • High-sensitivity
  • High-speed acquisition
  • Low-noise

AvaSpec-NIR-1
AvaSpec NIRLine

The AvaSpec NIRLine instruments are high-performance, near-infrared spectrometers that are optimized for the demands of measuring long wavelengths. This line provides leading-edge performance for dispersive NIR instruments with toroidal focusing mirrors and dynamic dark correction for enhanced stability. The NIRLine is comprised of both thermo-electrically cooled and un-cooled instruments. AvaSpec-NIR256-1.7 features an uncooled 256 pixel InGaAs detector.  All other instruments in the NIRLine have thermo-electric, peltier-cooled InGaAs detectors which support cooling down to -25°C against ambient.

AvaSpec NIRLine instruments are fully compatible with our AvaSpec StarLine and SensLine spectrometers. Avantes’ AvaSpec NIRLine instruments are available as laboratory instruments or OEM modules. AvaSpec NIRLine instruments are available with a number of premium options such as irradiance/intensity calibration and non-linearity calibration.

The AvaSpec NIRLine of instruments are designed to perform in a variety of applications such as:

  • Moisture content measurement of
  • liquids, solids and powders for inline
  • and quality control purposes
  • Quantitative and qualitative measurement of volatile organics such as ethanol, and methanol
  • Plastic characterization and material identification
  • Irradiance measurements, such as solar monitoring
  • Qualitative measurements of feed and food

Introduction Software

Introduction Software

AvaSoft is a software package that can be used to control all Avantes spectrometers and a wide range of accessories. The latest version can be used with Windows XP up to Windows 10. Since the initial version of AvaSoft in 1996, a major upgrade has been released at least once a year, featuring new options and possibilities.

Different versions

Our state of the art modular software is available as a scalable platform:

  • AvaSoft-Basic: Everything needed for basic measurements and controlling your AvaSpec series spectrometer, including basic data acquisition. Basic allows you to save and display data in the following modes: scope, transmission, absorption and relative irradiance.
  • AvaSoft-Full: Includes all possibilities of AvaSoft-Basic and adds many other options, such as history channel functions, auto-calibration procedures and external triggering.
  • Application add-on modules for AvaSoft-Full enable special measurement procedures: color measurements, absolute irradiance, chemometrics, process control and real-time export to Excel.
  • AvaSoft-All, which includes AvaSoft-Full and all add-on application modules in one package.
  • Stand-alone AvaSoft packages for pre-configured systems, such as AvaSoft-Raman for our Raman line of systems and AvaSoft-Thinfilm for measurements with the AvaThinfilm system.
  • Dynamic Link Library (DLL) interface packages with support for basic spectrometer control, color measurements and irradiance measurements.

Download & try

The most recent release of AvaSoft can be downloaded free of charge. The downloaded AvaSoft can be used by customers who already have an AvaSpec spectrometer and want to update their software version, but also by anyone who wants to try out the AvaSoft-FULL version and/or add-on applications. When no spectrometer is connected to the computer, AvaSoft will start in demo-mode, making it ideal to try out our software.
In demo-mode, the software will work as AvaSoft-Full, making it possible to test spectrometer functions and display and analyze spectra offline.


Introduction Light Sources

Introduction light sources

For applications such as transmission, absorption and reflection, illumination sources are needed. Avantes offers a wide range of different light sources, to suit your specific needs. An overview of the different options can be found on this page.

Different types of light sources

Tungsten Halogen light sources are mostly used to do measurements in the visible and NIR range. AvaLight Halogen sources provide a very stable output combined with long bulb lifetime. The high-stability enables their use in reflection and transmission configurations or as an irradiance calibration light source. Most importantly, the Halogen light’s spectral output is a smooth black body curve which provides for maximized dynamic range.

Avantes Deuterium light sources are known for their stable output and are used for UV absorption or reflection measurements. These can also be used as irradiance calibration sources due to their high-stability. The standard AvaLight-DH-S mixes the Halogen light with the Deuterium light, thus producing a wide spectral range light source. The output spectrum of Deuterium light sources exhibits several peaks, with a prominent peak at 656 nm. The AvaLight-DH-S-BAL incorporates a dichroic beam splitter installed to minimize these peaks, providing a smooth spectrum from 200-2500 nm.

Our pulsed Xenon light source is used in applications where a long lifetime and high output power is needed, such as in fluorescence measurements. This is an affordable UV source, but the spectral output is not as smooth and continuous as the AvaLight Halogen and Deuterium light sources. LED light sources provide high power at a precise wavelength. A typical application for AvaLight-LED sources is fluorescence. They provide long lifetime, short warm-up time and high-stability.

For wavelength calibration Avantes offers a variety of sources including Argon, Mercury- Argon, Neon, Zinc and Cadmium. All Avantes spectrometers are factory wavelength calibrated and do not require recalibration as they have fixed slits and optics. For those customers who wish to do their own calibrations, the AvaLight-CAL light sources can be used for recalibration purposes. For auto-calibration AvaSoft-Full provides a calibration procedure to make this easy.

Table Light sources

Application

Wavelength Range

Type

Principle

Product

Color / VIS / NIR

360-2500 nm

Tungsten Halogen

Continuous

AvaLight-HAL(-S)

DUV

190-400 nm

Deuterium

Continuous

AvaLight-D-S-DUV

UV

215-400 nm

Deuterium

Continuous

AvaLight-D-S

UV/VIS/NIR refl./abs.

215-2500 nm

Deuterium/Halogen

Continuous

AvaLight-DH-S-(BAL)

UV/VIS/NIR absorption

200-2500 nm

Deuterium/Halogen

Continuous

AvaLight-DHc

UV/VIS

200-1000 nm

Xenon

Pulsed

AvaLight-XE

Fluorescence

Multiple possible

LED

Continuous

AvaLight-LED

Wavelength Calibration

253-1704 nm

Mercury-Argon

Neon / Argon

Continuous

AvaLight-CAL

 

Irradiance Calibration

 

200-700 nm

Zinc / Cadmium

Continuous

AvaLight-CAL-CAD/Zinc

360-2500nm

Tungsten Halogen

Continuous

AvaLight-HAL-CAL

200-1100nm

Deuterium/Halogen

Continuous

AvaLight-DH-(BAL)-CAL

Radiance Calibration 360-2500 Tungsten Halogen Continuous AvaSphere-50-LS-HAL-CAL

Spectral distribution light sources

The spectral distribution of the different light source is given in this figure.

allspec2


Introduction Fiber Optics

Introduction Fiber-Optics

The use of fiber-optics as light guidance allows a great modularity and flexibility in the setup of an optical measurement system. Optical fibers can be made of many materials, such as plastic, glasses and silicates (SiO2). For high quality fiber-optics, as used in spectroscopic applications, synthetic fused silica (amorphous silicon dioxide) is used, that can be intentionally doped with trace elements to adjust the optical properties of the glass.

Basic principles

The basic principle of light transport through an optical fiber is total internal reflection. This means that the light within the numerical aperture of a fiber (NA = input acceptance cone) will be reflected and transported through the fiber. The size of the numerical aperture depends on the materials used for core and cladding.

Two basic types of silica fibers can be distinguished; single-mode and multi-mode fibers, depending on the propagation state of the light, traveling down the fiber. For most spectroscopic applications multi-mode fibers are used. Multi-mode fibers can be divided into 2 subcategories, step-index and graded-index. A relatively large core and high NA allow light to be easily coupled into the fiber, which allows the use of relatively inexpensive termination techniques. Step-index fibers are mainly used in spectroscopic applications.

Graded-index multimode fibers have a refractive index gradually decreasing from the core out through the cladding. Since the light travels faster in material with lower refractive index, the modal dispersion (amount of pulse-spreading) will be less.
These graded-index fibers are mainly used in telecommunication application, where dispersion at long distance (2-15 km) plays an important role.

Product codes

For example FC-20UV200-3-BX-SR
A product code is designed as follows:

 Type of product Total number of fibers Wavelength  Fiber core diameter Overall length Jacketing Other options

FC = standard fiber cable
FCB = bifurcated fiber
FCR = fiber reflection probe
FDP = fiber dip probe

Almost any number possible UV = 200-800 nm
IR = 350-2500 nm
UVIR = 250-2500 nm
8 μm*
50 μm**
100 μm
200 μm
400 μm
600 μm
800 μm**
1000 μm**
in meters BX =stainless steel
ME = chrome-plated brass
MS = metall silicone
SR = solarization resistant
HT= high temperature
HTX= extreme high temperature
PK= PEEK
HY= Hastelloy®

*Only for IR fibers
**Only for UV or IR fibers

Fiber-Optic Design

Core
Blz. 82 fiberoptic design
For spectroscopic applications, generally, multi-mode step index silica fibers are used. These range in core thickness from 50 to 1000 microns. The core is made out of pure silica. Other fiber cores with much higher absorption are made out of certain glass types or plastics. These are not offered in this catalog.
First a distinction is made between silica with high or low OH content. Silica fibers with high OH (600-1000 PPM) are used in the UV/VIS wavelength range because of the low absorption in the UV. They are referred to as UV/VIS fibers. For Deep-UV applications (below 230 nm) special solarization resistant fibers can be used.
The water content causes strong absorption peaks in the NIR wavelength range. In order to get good fibers for the NIR range, the “water” is removed from the silica. This results in low OH fibers (<2 PPM) with low absorption in the NIR. They are referred to as VIS/NIR fibers.
New in this catalog are the so-called broadband fibers, which can be used for the UV-NIR range (250-2500 nm), the product code for these fibers is UVIR.

Cladding
In order to get the light guiding effect the core is cladded with a lower index of refraction material. For the highest quality fibers with the lowest absorption this is a fluorine-doped silica, the so-called silica-silica or all-silica fibers with a numerical aperture (NA) of 0.22.

Buffers
blz. 83
Without further protection fibers would easily break, because of small scratches or other irregularities on the surface. Therefore a next layer, the buffer, is added. This buffer also determines under what circumstances the fiber can be used. Temperature range, radiation, vacuum, chemical environment and bending are factors to be considered.
Polyimide buffers offer a wide temperature range (-100 to 400°C) and superior solvent resistance. Also, this material is non-flammable. Drawbacks are sensitivity to micro bending and the difficulty to remove it.
 For extreme temperatures (-270 to 700°C) metal buffers are used. Metal buffers can withstand a continuous high temperature up to 500 °C and intermittent even up to 700°C. Low outgassing makes them also excellent for use in UHV environments.

Technical Data

Fiber Material Standard HTX
Temperature Range -190 °C to +400°C -270 °C to +700°C
Fiber type

Step index Mutimode

Core Numerical Aperture

0.22 ± 0.02

Buffer Polyimide Metal
Available Diameters 50/100/200/400/600/800/1000µm 200/400µm
Laser damage resistant core

1,3 kW/mm2 CW at 1060 nm, up to 10 J, pulsed

CW up to 100kW/cm2
For pulsed lasers (<1μs) 500kW/cm2

Bend radius

Momentary 100 x clad radius

Long term 600 x clad radius

Momentary 40 x clad radius

Long term 100 x clad radius

Transmission UV/VIS Fibers

uvfiber

Transmission VIS/NIR Fibers

irfiber

Transmission UV/VIS/NIR Fibers

pagina 101 bpi chart with line

Solarization Resistant Fibers for Deep UV applications

Most spectroscopic applications with fiber-optics have been restricted to wavelength ranges above 230 nm, because standard silica fibers with an undoped core and fluorine doped cladding are frequently damaged by exposure to deep-UV light (below 230 nm). This solarization effect is induced by the formation of “color centers” with an absorbance band of 214 nm. These color centers are formed when impurities (like Cl) exist in the core fiber material and form unbound electron pairs on the Si atom, which are affected by the deep-UV radiation.

Not long ago, solarization resistant fibers, which were hydrogen loaded, were developed (UVI). The disadvantage of these fibers is the limitation on smaller fiber diameters and limited lifetime, caused by the H2 outgassing from the fiber. Recently, with the availability of a modified core preform, a new fiber became available (UVM). This fiber provides long-term stability at 30-40% transmission (for 215 nm).

All UV/VIS fiber-optic probes, cables and bundles with core diameters of 100 µm, 200 µm, 400 µm, 600 µm, 800 µm and 1000 µm can be delivered with solarization resistant fibers. All assemblies, made by Avantes, are pre-solarized for an 8-hrs period, to have a constant transmission of 30-40% @ 215 nm.

 

Solarization normal UV400 fiber

solnormuv400

Solarization UV100-SR fiber

sol uvm100

Solarization 100 micron UVM fiber

sol100micron uvm0

Ordering Information

-SR

solarization resistant fiber for DUV applications

 

Fiber-Optic Jacketing

For different applications Avantes offers different jacketing material. Standard fiber-optic cables and bifurcated cables are protected by a Kevlar reinforced polypropylene inner tubing with PVC red outer jacket. All of our standard reflection probes are protected by a flexible stainless steel jacket with interlocking profile (BX) or a chrome-plated brass outer jacket, with hooked profile (ME) for optimal strain relief with silicon or PTFE inner tubing. For waterproof and some medical applications stainless steel spiral jacketing with glassilk and gray outer silicon rubber coating can be provided. Inside this jacket silicon or PTFE inner tubing is used as well. For heavy industrial environments we advise the metal stainless steel (-BX) jacketing. It features a tensile strength of 950N. Especially for small, flexible, endoscopic probes we use a PVC rubber jacketing. Some specifics on the jacketing can be found in the following technical information.Contact us if you have any special conditions requirements.

 

Technical Data

Sleeve material

Kevlar reinforced PVC

Chrome plated brass (ME)

Stainless steel (BX)

Silicon coated stainless steel (MS)

Stainless steel (FX)

Inner Tubing

Polypropylene

Silicon/PTFE

Silicon/PTFE

Silicon/PTFE

Steel/Copper

Outer dimensions

3.8 mm

5.0 mm

6.0 mm

5.8 mm

6.1 mm

Min. bending radius

18 mm

18 mm

35 mm

18 mm

35 mm

Temperature Range

-20°C to +65°C

-65°C to +250°C

-65°C to +250°C

-60°C to +180°C

-65°C to +250°C

Tensile Strength

150 N

350 N

950 N

70 N

n.a.

Application

Standard

Industrial

Heavy Industrial

Waterproof IP67

Industrial


Ordering Information

-MS Stainless steel spiral jacket with glassilk and gray outer silicon rubber coating
-ME Flexible chrome-plated brass outer jacket, with hooked profile
-BX Metal stainless steel jacket, with fully interlocking profile
-FX Stainless steel jacket for rigid/fixated set ups

 

 

 Standard

fiber-cables

 -MS
 -ME
 -BX
- FX

Fiber-Optic Probe Properties

All Avantes fiber-optic cables and probes can be modified to customers request. Most materials we use in our fiber-optic assemblies can be replaced with others to improve specific chemical or thermal resistance or to enhance vacuum or pressure properties. Please contact our fiber design engineers with your specific request.
In the following paragraphs some of the most essential technical parameters are listed for the materials we use.

Thermal resistance
The thermal resistance of a fiber-optic assembly depends on some of the materials used:

  1. Fiber, the standard fiber design has a polyimide buffer, covering a wide thermal range –190 to 400 °C. For higher temperatures metal clad coated (to 500°C) fibers are recommended.
  2. Jacketing, the standard jacketing is PVC based and has a small temperature range (-20°C to 65°C), for higher temperatures a flexible metal jacketing (-BX/ME) with silicone inner tubing is recommended (up to 250°C) or stainless steel tubing (not flexible, to 750°C).
  3. Probe ends, connectors and ferrules are standard made of metal and have a wide temperature range. For special plastics, like PVC, PEEK and Teflon a limited temperature range is applicable.
  4. Bonding epoxy, the standard epoxy used is a heat curing bonding epoxy with a temperature range of –60°C to 175°C. The curing temperature is standard 100 °C, for high temperature ranges (order code -HT), the curing temperature is 200°C. For the HTX (extreme high temperature) fibers and probes silver soldering is used, a process that can withstand temperatures up to 500°C.

 

Technical Data

Temperature range

Fiber

Sleeving

Probe end

Bonding

-20°C to +65°C

Standard Polyimide

Standard PVC

Standard metal/ PVC/PEEK/PTFE

Standard Epoxy

-30°C to +100°C

Standard Polyimide

Metal (-ME/-BX) or silicone (-MS)

Standard metal/ PEEK/PTFE

Standard Epoxy

-60°C to +200°C (HT)

Standard Polyimide

Metal (-ME/-BX) or silicone (-MS)

Standard metal/ PEEK/PTFE

High temperature curing epoxy

-100°C to +500°C (HTX)

Metal clad coated

BX/ME-jacket or none

metal

Silver soldering


Ordering Information

-HT High temperature version (up to 200°C)
-HTX Extreme high temperature version (up tp 500°C)


Chemical resistance

The chemical resistance of a fiber-optic assembly depends on some of the materials used:

  1. Fiber, the standard fiber design has a polyimide buffer, which normally will not be in contact with the sample; the quartz core provides good resistance against most solvents.
  2. Jacketing, the standard jacketing is PVC based and has a relative good chemical resistance. The –BX stainless steel and –ME chrome plated brass jacketing also have a good chemical resistance, but are not waterproof. The Silicone metal jacketing (-MS) is recommended for waterproof environment, biomedical applications, etc. The PEEK and PTFE jacketing have the best chemical resistance.
  3. Probe ends, connectors and ferrules are standard made of stainless steel (316) and are not very well suitable in corrosive environment. For most corrosive environments PEEK, PTFE or Hastelloy® C276 are recommended.
  4. Bonding, the standard heat-curing two- component epoxy used is resistant to water, inorganic acids and salts, alkalis and many aggressive organic solvents and most petrochemical products, and an extended range of organic and inorganic environments.


The table below gives a summary for the chemical resistance for most materials used. It has been drawn up on the basis of relevant sources in accordance with the state of the art; no claim to completeness. The data constitutes recommendations only, for which no liability can be accepted.

Please contact us if you have any doubt about the materials to use for your application.

Technical Data

Chemical environment

Fiber

Jacketing

Probe end

Epoxy

Acids weak

Standard Polyimide

±

-ME/-BX

-MS

-PEEK

-PVC

±

+

+

+

St. steel 316

PEEK

PTFE

Hastelloy® C276

-

+

+

+

+

Acids strong

Standard Polyimide

-

-ME/-BX

-MS

-PEEK

-PVC

-

±

+

±

St. steel 316

PEEK

PTFE

Hastelloy® C276

-

+

+

+

±

Bases weak

Standard Polyimide

±

-ME/-BX

-MS

-PEEK

-PVC

+

+

+

+

St. steel 316

PEEK

PTFE

Hastelloy® C276

+

+

+

+

+

Bases strong

Standard Polyimide

-

-ME/-BX

-MS

-PEEK

-PVC

+

+

+

+

St. steel 316

PEEK

PTFE

Hastelloy® C276

+

+

+

+

+

Aromatic carbons

Standard Polyimide

+

-ME/-BX

-MS

-PEEK

-PVC

+

+

+

+

St. steel 316

PEEK

PTFE

Hastelloy® C276

+

+

+

+

+

Alcohols

Standard Polyimide

±

-ME/-BX

-MS

-PEEK

-PVC

+

±

+

+

St. steel 316

PEEK

PTFE

Hastelloy® C276

+

+

+

+

+

Ketons/Ethers

Standard Polyimide

+

-ME/-BX

-MS

-PEEK

-PVC

+

-

+

-

St. steel 316

PEEK

PTFE

Hastelloy® C276

+

+

+

±

±

+ = good resistance
± = conditional resistant
- = not resistant

Ordering Information

-PK PEEK Probe material replaces Stainless Steel
-HY Hastelloy® C276 Probe material replaces Stainless Steel

Fiber-Optic Connectors

Standard SMA

 blz 88 SMA with ext fer

Standard SMA connector
We supply all of our standard fiber-optic cables, bundles and probes with SMA-905 connectors that easily fit into our complete range of spectrometers, light sources and accessories.
The SMA-905 connectors are screw-fitted and can be rotated over 360 degrees. The typical insertion loss for the connectors is 0.5 dB. The maximum filling diameter for bundles is 2.46 mm.

FC/PC connectors

blz 88 FCPC connector

FC/PC connectors
Optional FC/PC-connectors can be mounted to our fiber-optic products. The multimode FC/PC connectors have an extremely low insertion loss of < 0.2 dB. The FC/PC connector cannot rotate, always mounts into the same fixed position and therefore has a high reproducibility.

ST connectors

blz 88 ST-connector v4

ST connectors
Optional ST-connectors can be mounted to our fiber-optic products. ST-connectors easily mount with their bayonet type of fitting, and can therefore not rotate, i.e. they mount in a fixed position. The maximum filling diameter is 1.5 mm, typical insertion loss is 0.3 dB.

Ordering Information

-FC/PC FC/PC connector instead of standard SMA
-ST ST connector instead of standard SMA

Introduction Accessories

Introduction Accessories

To facilitate easier and more accurate measurements during an experiment, Avantes offers a wide selection of high quality accessories. From integrating spheres to cuvette holders, filter holders and fiber-optic multiplexers Avantes has you covered for your fiber-optic accessory needs.


Introduction Applications

Introduction Applications

On this section of the website we have listed some examples of the wide variety of applications Avantes spectrometers are used for. From plasma-wall-interaction to detection of explosives and from the Falkland Islands to Forest Fire detection in Portugal. Furthermore a number of measurement setups have been listed. Plasma, solar spectrum, Fluorescence and Absorbance measurements are just some of the many possibilities. But the Avantes Spectrometers can be used in many more applications.

Contact an application engineer to discuss your situation and the perfect spectroscopy solution for your needs.


Introduction OEM

Avantes as your OEM partner

Avantes has over 20 years of experience in applying spectroscopy and optical sensing technologies to enumerable environments and industries. Our partnership approach to working with Original Equipment Manufacturers (OEMs) is at the core of our success and philosophy as a business. For our OEM brochure click HERE

Working together with you

Avantes Sales Engineers follow a methodical discovery process with potential OEM customers to ensure our solution recommendation closely aligns with the needs of our customers. Upon reaching a consensus with our customers our team of engineers and support personnel works collaboratively to ensure successful integration and maximum interoperability. Avantes spectrometers, light sources and fiber optic sampling accessories provide the enabling technology for spectroscopy and material characterizations in these and many other industries:

  • Food and Beverage
  • Chemicals
  • Agriculture
  • Lighting
  • Biomedical Technologies
  • Metallurgy
  • Semiconductor/Thin Film

OEM spectrometer

AvaSpec - The OEM Spectrometer

The AvaSpec suite of instruments was designed with the rigors of OEM applications in mind. AvaSpec instruments offer superior resolution, sensivity, and electronic controls relative to comparable instruments on the market today. Avantes OEM customers are provided with a comprehensive OEM manual that details interfaces, wiring diagrams, instrument pinouts and connection information.

OEM optical bench

AvaBench Optical Bench

Avantes offers a range of high quality optical benches for OEM customers. The AvaBench-37.5, AvaBench-45, AvaBench-50, and AvaBench-75 all feature symmetrical Czerny-Turner design with a choice of fiber optic entrance connectors (SMA 905, FC/PC, ST). The AvaBench can be configured with any one of over 20 standard gratings covering 160-2500 nm and 16 detector arrays selected to meet the requirements of each application. Grating options range from a 150 line/mm grating for broadband applications through a 3600 line/mm grating for ultra-high resolution measurements. Avantes choice of detector arrays enables customer to meet the gamut of cost, sensitivity, resolution and signal to noise requirements associated with their OEM spectroscopy applications. Additional options include UV coatings, irradiance/non-linearity calibrations and detector collection lenses. For more detailed information about the Avabench, please click below.

Customization of Avantes optical bench designs is also available. Avantes optical bench technology can be integrated with customer’s proprietary or third party electronic boards, but can be best leveraged in combination with Avantes' proprietary AS5216 and ASC5216 electronics boards.

OEM electronics controllers

Electronics Controllers - AS-5216 & ASC-5216

Avantes optical benches can be controlled via our distinct electronics platforms. The AS-5216 and ASC-5216 platforms are capable of supporting all detector types and optical benches and provide superior performance and optimal configurability.

OEM software interface

Software Interface

Avantes proprietary AvaSoft operating software enables OEM customers to collect and save spectra in absorbance, reflection, transmittance, irradiance and scope modes. In addition to our base software solution, Avantes offers a variety of modular software add-ons for color measurement, thin film, process control and chemometry.

Most OEM applications prefer a more directed software solution for each application. Avantes Dynamic Linking Library (DLL) interface facilitates instrument control outside of our proprietary software. This interface contains functions that enable setting/getting hardware parameters from the spectrometers, designing functions for data acquisition, establishing communication with one, or multiple spectrometers and communication with other devices using TTL, digital, and analog input and output signals. The interface package also includes a number of sample programs developed to initiate writing an application in C++, Visual Basic, LabView, CSharp, Delphi and others. OEM customers are provided with a detailed manual on our DLL interface as well as direct software development support.

More information

For more information about Avantes OEM Solutions, please contact as . We look forward to speaking with you and assisting you with your application.


Introduction Solutions

Introduction solutions

Most of our customers have a clearly defined measurement they would like to address. Examples are color, absorbance and irradiance measurements. For these situations, Avantes has combined the best products to deliver solutions.

On these pages you will find a selection of the most popular solutions Avantes offers. Should your solution not be listed or do you need more information? Then don't hesitate to contact us!

For an overview of our bundles, featuring selected products for specific measurements, please open this PDF Brochure.


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