What is the grating constant d in college physics experiment?

The grating constant used in the experiment is generally around several hundred nanometers, such as d=650nm. The grating constant is generally about the order of the visible wavelength (the visible wavelength range is 460-720nm). The calculation formula is as follows:

λ is the wavelength, θ is the diffraction angle and m is a constant.

Grating is a combination of digital technology and traditional printing technology, which can show different special effects on special films. Show the lifelike three-dimensional world on the plane, the smooth animation fragments like movies, and the incredible illusion effect. Grating is a thin sheet composed of strip lenses. When we look at one side of the lens, we will see a thin line on the other side of the picture, and the position of this line is determined by the observation angle.

Grating constant is the distance between two scribed lines of a grating, which is expressed by d and is a length. So the unit is m (meter), but generally the grating constant is relatively small, and commonly used are mm (millimeter), um (micron) and nm (nanometer).

Extended data

An optical device consisting of a large number of parallel slits with equal width and equal spacing is called a grating. 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. The refined grating has thousands or even tens of thousands of notches in the width of 1cm. This kind of grating diffracted by transmitted light is called transmission grating, and there is also a grating diffracted by reflected light between two notches. For example, many parallel notches are carved on the surface plated with metal layer, and the smooth metal surface between the two notches can reflect light. This kind of grating is called reflection grating.

Grating constant is the distance between two gratings, expressed by d, and is an important parameter of gratings. Usually, diffraction gratings work based on Fraunhofer multi-slit diffraction effect. The formula describing the relationship between grating structure and incident angle and diffraction angle of light is called "grating equation".

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