This article is devoted to studying the quality of LEDs based on diffraction gratings. A layout of an optical setup for studying the optical characteristics of LEDs with a control system in the Delphi computer language has been developed. In high-end spectral instruments, diffraction gratings are used instead of prisms. Gratings are periodic structures engraved by a special dividing machine on the surface of a glass or metal plate (Figure 3.1). In good gratings, strokes parallel to each other have a length about 10 cm, and there are up to 2000 strokes per millimeter. In this case, the total length of the grating reaches 10–15 cm. The manufacture of such gratings requires the use of the highest technologies. In practice, coarser gratings with 50-100 lines per millimeter applied to the surface of the transparent film are also used. As a diffraction grating, may be used a piece of a CD (Fig. 1) or even a fragment of a CD (Fig. 1). 2. [1-4].

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