Grating is a very important optical element that can distinguish and separate spectra through different principles such as diffraction and interference. According to different classification standards, gratings can be classified into different types. This article will introduce several classification methods and characteristics of gratings.

1、 Divided according to the preparation method

According to the preparation method of gratings, they can be divided into three types: mechanical gratings, lithographic gratings, and holographic gratings.

Mechanical gratings are made using the mechanical marking method, with generally low marking accuracy, and are generally used in simple optical experiments in the laboratory. The photolithographic grating is made by using micro shadow technology, photoresist and Stepper, with high line marking accuracy, and can be made into very small optical holes. And holographic gratings are prepared using optical holographic technology, with high spatial frequency, strong directionality, and other characteristics. They are mainly used in optical information processing, laser holography, and other fields.

2、 Divided according to diffraction patterns

According to the diffraction mode of the grating, it can be divided into three types: transmission grating, reflection grating, and transmission reflection hybrid grating.

Transmission grating is an optical element that forms diffracted light after the light passes through the grating. It is generally made by photolithography or microelectronics processing technology, and is suitable for Optical instrument such as spectroscope and monochromator. Reflecting grating is a diffraction element of reflected light. The reflected light has different wavelengths and directions, and is commonly used in laser systems. The transparent and reflective hybrid grating is a hybrid type of transmission grating and reflection grating, which can disperse light into diffracted light and generate reflected light. It is commonly used in multi-color laser experiments.

3、 Divided according to diffraction order

According to the diffraction order of the grating, it can be divided into two types: first-order grating and high-order grating.

The first order grating refers to the grating that only produces the first order diffraction, and the generated diffracted light is diffracted only once, with little dispersion. It is commonly used in Optical instrument such as light splitting and monochromator. High order gratings refer to gratings that can generate second, third, and fourth order diffraction in addition to first-order diffraction, and can be used for polychromatic laser experiments and optical information processing.

Grating is a very important optical component, and different types of gratings have different characteristics and applications. We can choose different types of gratings according to actual needs.