What is a grating?

An optical device consisting of a large number of parallel slits with equal width and equal spacing is called a grating.

The earliest grating was made by German scientist J. Fraunhofer in 182 1 year, with thin metal wires tightly wound on two parallel thin screws. Because it looks like a fence, it is named "iron fence".

Modern gratings are engraved on glass or metal plates with precision scribing machines. Grating is the core component of grating spectrograph, and there are many kinds of grating spectrograph.

The commonly used grating is made by carving a large number of parallel notches on the glass plate. The notch is an opaque part, and the smooth part between two notches can transmit light, which is equivalent to a slit.

Extended data

Grating classification

It is divided into three-dimensional grating, grating ruler, anti-counterfeiting grating, replication grating, holographic grating, reflection grating and transmission (diffraction) grating. Basically, they are composed of a series of parallel slits with equal width and equal spacing, and there are often more than n notches in the length of1mm.

The notch is opaque, and the notch is opaque. We call it a transmission grating, and the other grating is a reflection grating. Some of them require special coating treatment. According to this yin-yang effect, there are more graphic mirrors, pattern mirrors and so on. It evolved. The simple principle is like a flashlight projected on the opposite wall to see the graphics.

Only one is dim and the other is macro. Just like carving on hair, the difficulty of the process is different. According to whether the light used is transmitted or reflected, it is divided into transmission grating and reflection grating.

According to its shape, it can be divided into plane grating and concave grating. In addition, there are holographic gratings, orthogonal gratings, phase gratings, show-off gratings and step gratings.

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