MSDD1000
Description
Specification
Configurations
Diffraction gratings

While choosing a device configuration it is important to select properly the diffraction gratings. A right selection of the diffraction grating allows one to obtain the best combination of high energetic efficiency and spectral resolution.

The basic grating parameters which determine their right choice you can find in the methodical material “Spectral Instrument. Basic Concepts and Characteristics.”

We propose a wide range of diffraction gratings to be used in the MSDD1000 series monochromator-spectrographs. Please, choose a necessary grating from the given below list, or consult our specialists.

Diffraction grating

Basic parameters for correct selection of diffraction gratings:

In the table “Selection of diffraction gratings” groove density and blaze wavelength belong to a diffraction grating parameters. Other parameters characterize a spectral device together with a selected grating.

  • Groove density
    The diffraction grating has a periodic structure. Such parameters as resolving power and free spectral range are determined by the periodic structure properties of a diffraction grating. The period of grating is the distance through which grooves are repeated. The reciprocal value of a grating period is called the groove density and displays the number of grooves in 1 mm.
  • Blaze wavelength
    The reflectivity of a grating depends on the grooves geometry, because the direction to the center of the diffraction maximum is determined by the mirror reflection of the incident beam from the edge of a groove. In spite of rather flat profile of diffraction maximum a blaze wavelength that corresponds to the maximum efficiency of the grating has been adopted as a feature for convenience of calculation. When selecting a grating it is useful to determine a blaze wavelength for a required grating on the spectral range of limited wavelengths WL1 and WL2. The blaze wavelength is determined by the ratio:
    WLBlaze = 2 ∙ WL1 ∙ WL2 / (WL1 + WL2).
  • Reciprocal linear dispersion
    The light from a grating in the focal plane of a spectral instrument forms a spectrum. Linear dispersion is used for a spectrum characteristic, which is defined as a reciprocal value of the product of angular dispersion of a grating and focal length of a spectral instrument and shows the spectral range that falls on a single linear distance in a focal plane.
  • The spectral resolution
    Limiting resolution of a spectral instrument is equal to the minimum half-width of its instrument function. The instrument function is determined by finite sizes of entrance diaphragm, aberrations and also distortions caused by inaccuracy in manufacturing and adjustment of optical elements of instrument. In addition, instrument function, and thus spectral resolution are dependent on lighting method of entrance slit, used aperture and registration system parameters.
  • Operating wavelength range
    Energy efficiency range referred to the wavelength region in which grating reflection coefficient is not less than 0.405 of the maximum. In the first order this range is limited by the wavelengths: ⅔ ∙ WLBlaze and 2 ∙ WLBlaze.
    Operating range usually corresponds to a grating energy efficiency. In some cases, for gratings with a high groove density and large blaze wavelength, the long-wave border of operating spectral range of instrument is limited by a maximal rotation angle of a grating which is defined by design of instrument.

Features of choosing the diffraction gratings for MSDD1000

MSDD1000 series monochromator-spectrograph serves for obtaining high spectral resolution with small size of the device, thus there are certain limitations when choosing gratings, connected with a specific optical schematic of this type of the device.

The MSDD1000 series is a double dispersion monochromator-spectrographs with the two-level arrangement of optical components to allow dispersion doubling.

In order to avoid downfall of two adjacent orders of the same decomposed in a spectrum wavelength from one grating to another, the spectral range of MSDD1000 series has limitations in a short-wave region for the gratings with low lines density.

The minimal operating wavelength values in nm for diffraction gratings with line density from 24 to 600 lines per mm are given in the table beside.

For gratings with high groove density, there is no limitation in a short-wave region.

Grating, l/mm Minimal operating wavelength, nm
600 300
400 450
300 600
200 900
150 1200
100 1800
75 2400
50 3600
37.5 4800
24 7500
  • Grating line density 600 l/mm: minimal operating wavelength 300 nm.
  • Grating line density 400 l/mm: minimal operating wavelength 450 nm.
  • Grating line density 300 l/mm: minimal operating wavelength 600 nm.
  • Grating line density 200 l/mm: minimal operating wavelength 900 nm.
  • Grating line density 150 l/mm: minimal operating wavelength 1200 nm.
  • Grating line density 100 l/mm: minimal operating wavelength 1800 nm.
  • Grating line density 75 l/mm: minimal operating wavelength 2400 nm.
  • Grating line density 50 l/mm: minimal operating wavelength 3600 nm.
  • Grating line density 37.5 l/mm: minimal operating wavelength 4800 nm.
  • Grating line density 24 l/mm: minimal operating wavelength 7500 nm.

Table for selection of diffraction gratings

Model Line density, mm-1 Blaze wavelength, nm *Reciprocal linear dispersion, nm/mm Spectral resolution, nm Operating wavelength range, nm Spectral range limited by the grating rotation angle, nm
783600 3600 hol 0.27** 0.0056 185 – 425 425
782422 2400 225 0.41 0.009 185 – 450 640
782427 2400 270 0.41 0.009 185 – 540 640
782770 2400 400 0.39 0.008 270 – 640 640
781827 1800 270 0.55 0.011 185 – 540 850
781840 1800 400 0.54 0.011 270 – 800 850
781840 1800 500 0.53 0.011 330 – 850 850
781875 1800 750 0.46 0.009 500 – 850 850
781225 1200 250 0.84 0.017 185 – 500 1280
781228 1200 280 0.84 0.017 190 – 560 1280
781240 1200 400 0.83 0.017 270 – 800 1280
781250 1200 500 0.82 0.017 335 – 1000 1280
781260 1200 600 0.81 0.017 400 – 1200 1280
781275 1200 750 0.79 0.016 500 – 1280 1280
780640 600 400 1.67 0.035 300 – 800 2560
780650 600 500 1.67 0.035 335 – 1000 2560
780660 600 600 1.67 0.035 400 – 1200 2560
780675 600 750 1.66 0.035 500 – 1500 2560
7804008 400 800 2.51 0.052 535 – 1600 3840
7804012 400 1200 2.49 0.052 800 – 2400 3840
7804017 400 1700 2.45 0.051 1135 – 3400 3840
7804020 400 2000 2.41 0.05 1335 – 3840 3840
7804025 400 2500 2.32 0.048 1670 – 3840 3840
780370 300 700 3.34 0.07 600 – 1400 5120
7803010 300 1000 3.34 0.07 670 – 2000 5120
7803015 300 1500 3.33 0.07 1000 – 3000 5120
7803020 300 2000 3.3 0.07 1335 – 4000 5120
7803030 300 3000 3.16 0.07 2000 – 5120 5120
7803035 300 3500 3.05 0.06 2330 – 5120 5120
7802015 200 1500 5 0.1 1000 – 3000 7680
7802020 200 2000 5 0.1 1335 – 4000 7680
7802025 200 2500 5 0.1 1670 – 5000 7680
7802030 200 3000 4.9 0.1 2000 – 6000 7680
7815030 150 3000 6.7 0.14 2000 – 6000 10240
7815045 150 4500 6.5 0.14 3000 – 9000 10240
7801025 100 2500 10 0.21 1800 – 5000 15360
7801030 100 3000 10 0.21 2000 – 6000 15360
7801042 100 4200 10 0.21 2770 – 8320 15360
7801048 100 4800 10 0.21 3230 – 9680 15360
7801055 100 5500 9.9 0.21 3670 – 11000 15360
7801062 100 6200 9.9 0.2 4130 – 12400 15360
7801072 100 7200 9.8 0.2 4800 – 14400 15360
7801088 100 8750 9.5 0.2 5830 – 15360 15360
7801097 100 9700 9.3 0.19 6470 – 15360 15360
7801103 100 10300 9.2 0.19 6870 – 15360 15360
7875070 75 7000 13.3 0.28 4670 – 14000 20480
7875095 75 9500 13 0.27 6330 – 19000 20480
7850038 50 3800 20 0.42 3600 – 7600 30720
7850063 50 6300 20 0.42 4200 – 12600 30720
7850070 50 7000 20 0.42 4670 – 14000 30720
7850083 50 8300 20 0.42 5530 – 16600 30720
7850124 50 12400 19.7 0.41 8270 – 24800 30720
7850169 50 16900 19.2 0.4 11270 – 30720 30720
7850200 50 20000 18.6 0.38 13330 – 30720 30720
7837093 37.5 9300 26.7 0.55 6200 – 18600 40960
7837156 37.5 15600 26.4 0.55 10400 – 31200 40960
7824116 24 11600 41.8 0.87 7730 – 23200 64000
7824144 24 14400 41.8 0.87 9600 – 28800 64000
7824173 24 17300 41.7 0.86 11530 – 34600 64000
7824243 24 24300 41.3 0.86 16200 – 48600 64000
7824285 24 28500 40.8 0.85 19000 – 57000 64000
7824325 24 32500 40.3 0.84 21670 – 64000 64000

Gratings with line density
3600 mm-1

  • Model 783600: blaze wavelength = hol; *reciprocal linear dispersion = 0.27** nm/mm; spectral resolution = 0.0056 nm; operating wavelength range = 185-425 nm; spectral range limited by the grating rotation angle = 425 nm.

Gratings with line density
2400 mm-1

  • Model 782422: blaze wavelength = 225 nm; *reciprocal linear dispersion = 0.41 nm/mm; spectral resolution = 0.009 nm; operating wavelength range = 185-450 nm; spectral range limited by the grating rotation angle = 640 nm.
  • Model 782427: blaze wavelength = 270 nm; *reciprocal linear dispersion = 0.41 nm/mm; spectral resolution = 0.009 nm; operating wavelength range = 185-540 nm; spectral range limited by the grating rotation angle = 640 nm.
  • Model 782770: blaze wavelength = 400 nm; *reciprocal linear dispersion = 0.39 nm/mm; spectral resolution = 0.008 nm; operating wavelength range = 270-640 nm; spectral range limited by the grating rotation angle = 640 nm.

Gratings with line density
1800 mm-1

  • Model 781827: blaze wavelength = 270 nm; *reciprocal linear dispersion = 0.55 nm/mm; spectral resolution = 0.011 nm; operating wavelength range = 185-540 nm; spectral range limited by the grating rotation angle = 850 nm.
  • Model 781840: blaze wavelength = 400 nm; *reciprocal linear dispersion = 0.54 nm/mm; spectral resolution = 0.011 nm; operating wavelength range = 270-800 nm; spectral range limited by the grating rotation angle = 850 nm.
  • Model 781840: blaze wavelength = 500 nm; *reciprocal linear dispersion = 0.53 nm/mm; spectral resolution = 0.011 nm; operating wavelength range = 330-850 nm; spectral range limited by the grating rotation angle = 850 nm.
  • Model 781875: blaze wavelength = 750 nm; *reciprocal linear dispersion = 0.46 nm/mm; spectral resolution = 0.009 nm; operating wavelength range = 500-850 nm; spectral range limited by the grating rotation angle = 850 nm.

Gratings with line density
1200 mm-1

  • Model 781225: blaze wavelength = 250 nm; *reciprocal linear dispersion = 0.84 nm/mm; spectral resolution = 0.017 nm; operating wavelength range = 185-500 nm; spectral range limited by the grating rotation angle = 1280 nm.
  • Model 781228: blaze wavelength = 280 nm; *reciprocal linear dispersion = 0.84 nm/mm; spectral resolution = 0.017 nm; operating wavelength range = 190-560 nm; spectral range limited by the grating rotation angle = 1280 nm.
  • Model 781240: blaze wavelength = 400 nm; *reciprocal linear dispersion = 0.83 nm/mm; spectral resolution = 0.017 nm; operating wavelength range = 270-800 nm; spectral range limited by the grating rotation angle = 1280 nm.
  • Model 781250: blaze wavelength = 500 nm; *reciprocal linear dispersion = 0.82 nm/mm; spectral resolution = 0.017 nm; operating wavelength range = 335-1000 nm; spectral range limited by the grating rotation angle = 1280 nm.
  • Model 781260: blaze wavelength = 600 nm; *reciprocal linear dispersion = 0.81 nm/mm; spectral resolution = 0.017 nm; operating wavelength range = 400-1200 nm; spectral range limited by the grating rotation angle = 1280 nm.
  • Model 781275: blaze wavelength = 750 nm; *reciprocal linear dispersion = 0.79 nm/mm; spectral resolution = 0.016 nm; operating wavelength range = 500-1280 nm; spectral range limited by the grating rotation angle = 1280 nm.

Gratings with line density
600 mm-1

  • Model 780640: blaze wavelength = 400 nm; *reciprocal linear dispersion = 1.67 nm/mm; spectral resolution = 0.035 nm; operating wavelength range = 300-800 nm; spectral range limited by the grating rotation angle = 2560 nm.
  • Model 780650: blaze wavelength = 500 nm; *reciprocal linear dispersion = 1.67 nm/mm; spectral resolution = 0.035 nm; operating wavelength range = 335-1000 nm; spectral range limited by the grating rotation angle = 2560 nm.
  • Model 780660: blaze wavelength = 600 nm; *reciprocal linear dispersion = 1.67 nm/mm; spectral resolution = 0.035 nm; operating wavelength range = 400-1200 nm; spectral range limited by the grating rotation angle = 2560 nm.
  • Model 780675: blaze wavelength = 750 nm; *reciprocal linear dispersion = 1.66 nm/mm; spectral resolution = 0.035 nm; operating wavelength range = 500-1500 nm; spectral range limited by the grating rotation angle = 2560 nm.

Gratings with line density
400 mm-1

  • Model 7804008: blaze wavelength = 800 nm; *reciprocal linear dispersion = 2.51 nm/mm; spectral resolution = 0.052 nm; operating wavelength range = 535-1600 nm; spectral range limited by the grating rotation angle = 3840 nm.
  • Model 7804012: blaze wavelength = 1200 nm; *reciprocal linear dispersion = 2.49 nm/mm; spectral resolution = 0.052 nm; operating wavelength range = 800-2400 nm; spectral range limited by the grating rotation angle = 3840 nm.
  • Model 7804017: blaze wavelength = 1700 nm; *reciprocal linear dispersion = 2.45 nm/mm; spectral resolution = 0.051 nm; operating wavelength range = 1135-3400 nm; spectral range limited by the grating rotation angle = 3840 nm.
  • Model 7804020: blaze wavelength = 2000 nm; *reciprocal linear dispersion = 2.41 nm/mm; spectral resolution = 0.05 nm; operating wavelength range = 1335-3840 nm; spectral range limited by the grating rotation angle = 3840 nm.
  • Model 7804025: blaze wavelength = 2500 nm; *reciprocal linear dispersion = 2.32 nm/mm; spectral resolution = 0.048 nm; operating wavelength range = 1670-3840 nm; spectral range limited by the grating rotation angle = 3840 nm.

Gratings with line density
300 mm-1

  • Model 780370: blaze wavelength = 700 nm; *reciprocal linear dispersion = 3.34 nm/mm; spectral resolution = 0.07 nm; operating wavelength range = 600-1400 nm; spectral range limited by the grating rotation angle = 5120 nm.
  • Model 7803010: blaze wavelength = 1000 nm; *reciprocal linear dispersion = 3.34 nm/mm; spectral resolution = 0.07 nm; operating wavelength range = 670-2000 nm; spectral range limited by the grating rotation angle = 5120 nm.
  • Model 7803015: blaze wavelength = 1500 nm; *reciprocal linear dispersion = 3.33 nm/mm; spectral resolution = 0.07 nm; operating wavelength range = 1000-3000 nm; spectral range limited by the grating rotation angle = 5120 nm.
  • Model 7803020: blaze wavelength = 2000 nm; *reciprocal linear dispersion = 3.3 nm/mm; spectral resolution = 0.07 nm; operating wavelength range = 1335-4000 nm; spectral range limited by the grating rotation angle = 5120 nm.
  • Model 7803030: blaze wavelength = 3000 nm; *reciprocal linear dispersion = 3.16 nm/mm; spectral resolution = 0.07 nm; operating wavelength range = 2000-5120 nm; spectral range limited by the grating rotation angle = 5120 nm.
  • Model 7803035: blaze wavelength = 3500 nm; *reciprocal linear dispersion = 3.05 nm/mm; spectral resolution = 0.06 nm; operating wavelength range = 2330-5120 nm; spectral range limited by the grating rotation angle = 5120 nm.

Gratings with line density
200 mm-1

  • Model 7802015: blaze wavelength = 1500 nm; *reciprocal linear dispersion = 5 nm/mm; spectral resolution = 0.1 nm; operating wavelength range = 1000-3000 nm; spectral range limited by the grating rotation angle = 7680 nm.
  • Model 7802020: blaze wavelength = 2000 nm; *reciprocal linear dispersion = 5 nm/mm; spectral resolution = 0.1 nm; operating wavelength range = 1335-4000 nm; spectral range limited by the grating rotation angle = 7680 nm.
  • Model 7802025: blaze wavelength = 2500 nm; *reciprocal linear dispersion = 5 nm/mm; spectral resolution = 0.1 nm; operating wavelength range = 1670-5000 nm; spectral range limited by the grating rotation angle = 7680 nm.
  • Model 7802030: blaze wavelength = 3000 nm; *reciprocal linear dispersion = 4.9 nm/mm; spectral resolution = 0.1 nm; operating wavelength range = 2000-6000 nm; spectral range limited by the grating rotation angle = 7680 nm.

Gratings with line density
150 mm-1

  • Model 7815030: blaze wavelength = 3000 nm; *reciprocal linear dispersion = 6.7 nm/mm; spectral resolution = 0.14 nm; operating wavelength range = 2000-6000 nm; spectral range limited by the grating rotation angle = 10240 nm.
  • Model 7815045: blaze wavelength = 4500 nm; *reciprocal linear dispersion = 6.5 nm/mm; spectral resolution = 0.14 nm; operating wavelength range = 3000-9000 nm; spectral range limited by the grating rotation angle = 10240 nm.

Gratings with line density
100 mm-1

  • Model 7801025: blaze wavelength = 2500 nm; *reciprocal linear dispersion = 10 nm/mm; spectral resolution = 0.21 nm; operating wavelength range = 1800-5000 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801030: blaze wavelength = 3000 nm; *reciprocal linear dispersion = 10 nm/mm; spectral resolution = 0.21 nm; operating wavelength range = 2000-6000 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801042: blaze wavelength = 4200 nm; *reciprocal linear dispersion = 10 nm/mm; spectral resolution = 0.21 nm; operating wavelength range = 2770-8320 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801048: blaze wavelength = 4800 nm; *reciprocal linear dispersion = 10 nm/mm; spectral resolution = 0.21 nm; operating wavelength range = 3230-9680 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801055: blaze wavelength = 5500 nm; *reciprocal linear dispersion = 9.9 nm/mm; spectral resolution = 0.21 nm; operating wavelength range = 3670-11000 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801062: blaze wavelength = 6200 nm; *reciprocal linear dispersion = 9.9 nm/mm; spectral resolution = 0.2 nm; operating wavelength range = 4130-12400 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801072: blaze wavelength = 7200 nm; *reciprocal linear dispersion = 9.8 nm/mm; spectral resolution = 0.2 nm; operating wavelength range = 4800-14400 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801088: blaze wavelength = 8750 nm; *reciprocal linear dispersion = 9.5 nm/mm; spectral resolution = 0.2 nm; operating wavelength range = 5830-15360 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801097: blaze wavelength = 9700 nm; *reciprocal linear dispersion = 9.3 nm/mm; spectral resolution = 0.19 nm; operating wavelength range = 6470-15360 nm; spectral range limited by the grating rotation angle = 15360 nm.
  • Model 7801103: blaze wavelength = 10300 nm; *reciprocal linear dispersion = 9.2 nm/mm; spectral resolution = 0.19 nm; operating wavelength range = 6870-15360 nm; spectral range limited by the grating rotation angle = 15360 nm.

Gratings with line density
75 mm-1

  • Model 7875070: blaze wavelength = 7000 nm; *reciprocal linear dispersion = 13.3 nm/mm; spectral resolution = 0.28 nm; operating wavelength range = 4670-14000 nm; spectral range limited by the grating rotation angle = 20480 nm.
  • Model 7875095: blaze wavelength = 9500 nm; *reciprocal linear dispersion = 13 nm/mm; spectral resolution = 0.27 nm; operating wavelength range = 6330-19000 nm; spectral range limited by the grating rotation angle = 20480 nm.

Gratings with line density
50 mm-1

  • Model 7850038: blaze wavelength = 3800 nm; *reciprocal linear dispersion = 20 nm/mm; spectral resolution = 0.42 nm; operating wavelength range = 3600-7600 nm; spectral range limited by the grating rotation angle = 30720 nm.
  • Model 7850063: blaze wavelength = 6300 nm; *reciprocal linear dispersion = 20 nm/mm; spectral resolution = 0.42 nm; operating wavelength range = 4200-12600 nm; spectral range limited by the grating rotation angle = 30720 nm.
  • Model 7850070: blaze wavelength = 7000 nm; *reciprocal linear dispersion = 20 nm/mm; spectral resolution = 0.42 nm; operating wavelength range = 4670-14000 nm; spectral range limited by the grating rotation angle = 30720 nm.
  • Model 7850083: blaze wavelength = 8300 nm; *reciprocal linear dispersion = 20 nm/mm; spectral resolution = 0.42 nm; operating wavelength range = 5530-16600 nm; spectral range limited by the grating rotation angle = 30720 nm.
  • Model 7850124: blaze wavelength = 12400 nm; *reciprocal linear dispersion = 19.7 nm/mm; spectral resolution = 0.41 nm; operating wavelength range = 8270-24800 nm; spectral range limited by the grating rotation angle = 30720 nm.
  • Model 7850169: blaze wavelength = 16900 nm; *reciprocal linear dispersion = 19.2 nm/mm; spectral resolution = 0.4 nm; operating wavelength range = 11270-30720 nm; spectral range limited by the grating rotation angle = 30720 nm.
  • Model 7850200: blaze wavelength = 20000 nm; *reciprocal linear dispersion = 18.6 nm/mm; spectral resolution = 0.38 nm; operating wavelength range = 13330-30720 nm; spectral range limited by the grating rotation angle = 30720 nm.

Gratings with line density
37.5 mm-1

  • Model 7837093: blaze wavelength = 9300 nm; *reciprocal linear dispersion = 26.7 nm/mm; spectral resolution = 0.55 nm; operating wavelength range = 6200-18600 nm; spectral range limited by the grating rotation angle = 40960 nm.
  • Model 7837156: blaze wavelength = 15600 nm; *reciprocal linear dispersion = 26.4 nm/mm; spectral resolution = 0.55 nm; operating wavelength range = 10400-31200 nm; spectral range limited by the grating rotation angle = 40960 nm.

Gratings with line density
24 mm-1

  • Model 7824116: blaze wavelength = 11600 nm; *reciprocal linear dispersion = 41.8 nm/mm; spectral resolution = 0.87 nm; operating wavelength range = 7730-23200 nm; spectral range limited by the grating rotation angle = 64000 nm.
  • Model 7824144: blaze wavelength = 14400 nm; *reciprocal linear dispersion = 41.8 nm/mm; spectral resolution = 0.87 nm; operating wavelength range = 9600-28800 nm; spectral range limited by the grating rotation angle = 64000 nm.
  • Model 7824173: blaze wavelength = 17300 nm; *reciprocal linear dispersion = 41.7 nm/mm; spectral resolution = 0.86 nm; operating wavelength range = 11530-34600 nm; spectral range limited by the grating rotation angle = 64000 nm.
  • Model 7824243: blaze wavelength = 24300 nm; *reciprocal linear dispersion = 41.3 nm/mm; spectral resolution = 0.86 nm; operating wavelength range = 16200-48600 nm; spectral range limited by the grating rotation angle = 64000 nm.
  • Model 7824285: blaze wavelength = 28500 nm; *reciprocal linear dispersion = 40.8 nm/mm; spectral resolution = 0.85 nm; operating wavelength range = 19000-57000 nm; spectral range limited by the grating rotation angle = 64000 nm.
  • Model 7824325: blaze wavelength = 32500 nm; *reciprocal linear dispersion = 40.3 nm/mm; spectral resolution = 0.84 nm; operating wavelength range = 21670-64000 nm; spectral range limited by the grating rotation angle = 64000 nm.

* At the blaze wavelength.
** At the wavelength 255 nm.
For blaze wavelength 2000 nm and shorter the data is measured by multielement detectors with entrance slit 15 microns.
For the wavelength more than 2000 nm the data is obtained by calculation with the entrance slit 15 microns.