Difraction gratings

HoloGrate, JSC manufactures the holographic difraction gratings of the following types:

• Plane Reflecting Gratings Constant Spacing;
• Concave Gratings (I type);
• Concave Aberration Corrected Gratings (types II-IV);
• Relief difraction holographic elements;
• High power gratings for lasers, including gratings for use in pulse compression;
• Special gratings for measurements.

What is a difraction grating?

Holographic gratings represent the number of periodical microgrooves having approximate size about parts of micron. This microgrooves have a difraction effect.
The microgroove surface does not reflect an incident light as a mirror. It transforms incident “white” light to “rainbow” colours.
The base technology of our company is the photoresist technology based on the original high-resolution inorganic resist. This is the universal technology for producing of holographic gratings, relief-phase holograms and for high-resolution lithography.

How does it work?

Diffraction gratings, representing precise system of grooves with certain profile ruled on plane or concave optical surface, are applied in spectral instruments, lasers and some other devices as a dispersing element. Holographic difraction gratings are produced by means of interference pattern recording on a photosensitive material, deposited to an optically flat glass, then developed and provided with reflective coating in vacuum.
Chalcogenide glass thin film is used as photoresist to fabricate the grooved structure on difraction gratings. The structure of a grating presents a combination of grooves with a quasi-sinusoidal profile. Now HoloGrate, JSC masters the production of holographic difraction gratings with asymmetric profile.

Spectral range

100-1300 nm at first order with 600-3600 grooves per millimeter, besides gratings for HUV and soft X-ray range.

The dimention of gratings

up to 200x400 for plane gratings;
up to 200 mm Dia for concave gratings with relative aperture 1:3.

Holographic Gratings features

• efficiency depends on wave length/grating period ratio;
• no “ghosts”;
• low light scattering level and high signal/noise ratio;
• high brightness efficiency along the whole surface and without limiting of aperture size

Plane Holographic Difraction Grating basic parameters

relative intensity of light scattering at 10 Аngstrom distance from spectrum line distance (less or equal) 5x10-7 (1x10-7 is possible for some gratings);
reflectance: at energy concentration maximum up to 95% at the band boundaries 30-40%;
grating resolution / its theoretical value ratio >0,9.

Concave Holographic Diffraction Grating can be fabricated for Customer's instrument scheme with aberration correction and reflectance optimization.

Our gratings are provided with various reflective coatings, i.e.:

Al coating deposited in vacuum by means of different techniques (resistive evaporation; resistive evaporation and ion-beam processing combination; electron-beam processing; ion-beam processing)
Al + MgF₂coating (Al deposited by resistive method and MgF₂ by electron-beam processing)
Au coating deposited by means resistive method.
To increase beam stability metal and dielectric multi-layer combination are applied.

For more detailed information: grating@holograte.com