Concave Blazed Holographic Gratings
A concave grating has the advantage of setting up a spectroscopic system without any imaging optics like concave mirrors. For this reason, the concave grating is used in a wide range of applications, such as analytical instruments, optical communications, biotechnology, and medical instruments. Spectroscopes incorporating concave gratings are classified roughly into two categories: polychromators or monochromators. Shimadzu offers concave gratings for applications in (1)flat-field polychromators and (2)constant deviation monochromators.
- As a concave grating itself has the aberration correction function, it is possible to design a compact spectroscopic system by a concave grating in higher resolution than by a mechanically ruled grating.
- Concave gratings with small radius of curvatures are available. It is also possible to make concave gratings with high aperture ratios for fluorescence analysis and optical communication applications.
- All the concave gratings for flat-field polychromators and constant deviation monochromators are aberration corrected by the optimum exposure method of Shimadzu's Aspherical Wave Exposure Technology and have excellent imaging performance.
- The grating grooves are formed by a holographic exposure method which applies two-laser-light interference. This holographic method ensures that the stray light ,due to periodical errors of grooves, of concave gratings is much smaller than that of mechanically ruled gratings.
- Blaze angle is formed by an ion-beam etching technology which easily makes blazed holographic gratings with various blaze angles (blaze wavelengths).
- High groove density and high resolution gratings can be manufactured easily and at competitive price.
Fig.3 Shape of Concave Gratings
|Grating Type||Unequally spaced curved-groove replica grating*1|
|Blank material||Soda glass|
Width(W) and hegiht (H) of rectangular blanks
Diameter(Φ) of round blanks
|Effective area||Total area less a 2mm strip around the perimeter|
|Groove density tolerance (at center of grating)||±2 grooves/mm|
|Coating (vacuum evaporation)||Aluminum (Aℓ)|
|Scratches and digs||80-50 (in accordance with MIL-O-13830A)|
- When you need special concave gratings other than our standard, please contact us.
- Holographic gratings (HG) are also available.