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. ## 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/mmMinimal operating wavelength, nm
600300
400450
300600
200900
1501200
1001800
752400
503600
37.54800
247500
• 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

ModelLine density, mm-1Blaze wavelength, nm*Reciprocal linear dispersion, nm/mmSpectral resolution, nmOperating wavelength range, nmSpectral range limited by the grating rotation angle, nm
7836003600hol0.27**0.0056185 – 425425
78242224002250.410.009185 – 450640
78242724002700.410.009185 – 540640
78277024004000.390.008270 – 640640
78182718002700.550.011185 – 540850
78184018004000.540.011270 – 800850
78184018005000.530.011330 – 850850
78187518007500.460.009500 – 850850
78122512002500.840.017185 – 5001280
78122812002800.840.017190 – 5601280
78124012004000.830.017270 – 8001280
78125012005000.820.017335 – 10001280
78126012006000.810.017400 – 12001280
78127512007500.790.016500 – 12801280
7806406004001.670.035300 – 8002560
7806506005001.670.035335 – 10002560
7806606006001.670.035400 – 12002560
7806756007501.660.035500 – 15002560
78040084008002.510.052535 – 16003840
780401240012002.490.052800 – 24003840
780401740017002.450.0511135 – 34003840
780402040020002.410.051335 – 38403840
780402540025002.320.0481670 – 38403840
7803703007003.340.07600 – 14005120
780301030010003.340.07670 – 20005120
780301530015003.330.071000 – 30005120
780302030020003.30.071335 – 40005120
780303030030003.160.072000 – 51205120
780303530035003.050.062330 – 51205120
7802015200150050.11000 – 30007680
7802020200200050.11335 – 40007680
7802025200250050.11670 – 50007680
780203020030004.90.12000 – 60007680
781503015030006.70.142000 – 600010240
781504515045006.50.143000 – 900010240
78010251002500100.211800 – 500015360
78010301003000100.212000 – 600015360
78010421004200100.212770 – 832015360
78010481004800100.213230 – 968015360
780105510055009.90.213670 – 1100015360
780106210062009.90.24130 – 1240015360
780107210072009.80.24800 – 1440015360
780108810087509.50.25830 – 1536015360
780109710097009.30.196470 – 1536015360
7801103100103009.20.196870 – 1536015360
787507075700013.30.284670 – 1400020480
7875095759500130.276330 – 1900020480
7850038503800200.423600 – 760030720
7850063506300200.424200 – 1260030720
7850070507000200.424670 – 1400030720
7850083508300200.425530 – 1660030720
7850124501240019.70.418270 – 2480030720
7850169501690019.20.411270 – 3072030720
7850200502000018.60.3813330 – 3072030720
783709337.5930026.70.556200 – 1860040960
783715637.51560026.40.5510400 – 3120040960
7824116241160041.80.877730 – 2320064000
7824144241440041.80.879600 – 2880064000
7824173241730041.70.8611530 – 3460064000
7824243242430041.30.8616200 – 4860064000
7824285242850040.80.8519000 – 5700064000
7824325243250040.30.8421670 – 6400064000

### 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.