Two categories of grating encoders

Grating fabrication, also called diffraction grating fabrication. An optical element that uses dispersive diffraction to make light dispersive (resolved into spectra). It is a carved piece of a large number of parallel equidistant (slit width, line) of flat glass or metal sheet. Gratings make large numbers of slits, usually tens to thousands of pieces per millimeter. Monochromatic parallel light makes the diffraction of each slit and interference between the slits through the grating, forming a pattern of very broad dark stripes and very fine stripes. These sharp, bright stripes are called spectral lines. The position of spectral lines varies with wavelength. When the polychromatic light is fabricated through the grating, the spectral lines of different wavelengths appear at different positions to form a spectrum. The formation of light through grating is a common result of single slit diffraction and multi slit interference.

As the core of spectrum instrument, grating fabrication and application level directly affect the development of spectrum instrument industry. At present, the research institutions engaged in grating manufacturing technology in China are only a few of Changchun Institute of Optics and optics, Tsinghua University and University of Science and Technology of China, and lack of investment and long-term planning. Metrology grating manufacturing has been widely used in precision measurement, automatic positioning, tracking test and optical information processing. The quality of grating manufacturing, the accuracy, the cost and the manufacturing efficiency will directly affect the accuracy and performance of grating manufacturing measuring instruments.

The grating encoder can be divided into two major categories, one is the rotary encoder, which is used for the measurement of rotation angle and speed; two, the ruler type encoder is used for the measurement of the linear displacement and the speed of movement. In the rotary encoder, it can be divided into absolute encoder and incremental encoder.