The decorative film of the pvd coating machine telescope is different from the anti-reflection and anti-reflection coating, it is not completely designed to improve the optical quality of the lens. But to expand sales, adapt to consumer psychology and other needs, and for its uncomplicated uses, to a certain extent sacrifice optical properties to improve decoration.

       Because customers are generally interested in gem-like sparkling objects and mysteries such as "infrared" and "broadband green films," the decorative films for telescopes are generally more reflective red or green. The decorative film of pvd coating equipment is generally used as an ordinary anti-reflection film whose center wavelength is changed for decoration purposes or a strong reflection film for a certain wavelength. In the following, the cyan film and the ruby film are taken as examples for description.
       1. Blue-green film Thicker single-layer coating reflects blue-white light. According to the diffraction theory, the coating is thicker, and the center wavelength of the antireflection is also shifted to the long waveband (red light) direction. At this time, there are more blue-green light reflections and less red light reflections. It is cyan, red, green and blue are mixed into white, and a small amount of white light and cyan light are mixed to form a blue-white reflection with poor saturation. Because the single-layer coating of the pvd coating machine is used, the reflection is stronger than that of the multi-layer film. The bright and beautiful turquoise coating of vacuum coating equipment can achieve a good decorative effect, and it is the same "green film" as the emerald green bimodal broadband film, so it is often sold well.
       2. The purpose of the ruby film is for high-definition observation in strong light environments such as desert Gobi, snow, and reflective water surfaces under the hot sun. On the premise of retaining the large aperture of the telescope, the pvd coating machine uses reflection to reduce the incidence of red light to weaken the strong The light stimulates the naked eye and increases the decorative effect of the coating. Since the anti-reflection ability of the pvd coating machine coating is only related to the refractive index of the coating and the glass substrate, the film is anti-reflection in other wavelength bands. However, due to the loss of a large amount of red light, the color reproduction is generally obviously blue-blue. Its significance is equivalent to adding a fixed light cyan filter to the conventional large-aperture telescope. This also shortens the central wavelength of the light passing through the lens, and according to the principle of improving diffraction resolution, the clarity will be further improved.
       In addition, there are strong reflective green film, yellow film and less reflective red film, etc. The principle is the same as that of ruby film and cyan film respectively.