Different types of optical gratings and their working principles

Diffraction Grating

Diffraction gratings are the most common type of gratings and operate based on the principles of light diffraction and interference. When a beam of light passes through a grating, light of different wavelengths diffracts at different angles, forming a spectrum. The diffraction formula for gratings is:
dsinθ=nλ

Where (d) is the grating constant, (\theta) is the diffraction angle, (n) is the diffraction order, and (\lambda) is the wavelength of light.

Reflective Grating

Reflective gratings form spectra through the reflection of light. When light rays are incident on the grating surface, due to the presence of numerous parallel grooves, light of different wavelengths reflects and interferes at different angles, producing a spectrum. Reflective gratings are commonly used in high-precision spectrometers.

Transmission Grating

Transmission gratings form spectra through the transmission of light rays. As light passes through the grating, the presence of numerous parallel slits on the grating surface causes light of different wavelengths to transmit and interfere at different angles, generating a spectrum. Transmission gratings are often used in educational and experimental settings.

Holographic Grating

Holographic gratings are fabricated by recording interference fringes on photosensitive materials using laser interference technology. Their operating principle is similar to that of diffraction gratings, but due to the different manufacturing process, holographic gratings exhibit higher diffraction efficiency and superior spectral resolution.

Concave Grating

Concave gratings are a special type of reflective grating with a concave surface structure. They can not only disperse light but also focus it, serving both dispersion and focusing functions in spectrometers, thereby simplifying the optical system.

Blazed Grating

Blazed gratings are optimized for diffraction efficiency by engraving specific angled grooves on the grating surface, maximizing the diffraction intensity of a particular wavelength of light in a specific direction. Blazed gratings are commonly used in applications requiring high-efficiency spectral analysis.