The definition of prism

Sep. 25, 2019

The prism is a polyhedron made of a transparent material such as glass or crystal. It is widely used in optical instruments. Prisms can be divided into several types according to their nature and use. For example, in a spectroscopic instrument, a composite lens is decomposed into a "dispersion prism" of a spectrum, More commonly used are equilateral prisms; in the periscope, binoculars and other instruments to change the direction of light, thereby adjusting its imaging position called "total reflection prism", generally using right angle prism.

The side of the prism: the plane from which the light is incident is called the side.

Right Angle Prism

Right Angle Prism

The main section of the prism: the plane perpendicular to the side is called the main section. According to the shape of the main section, it can be divided into a triangular prism, a right-angle prism, a penta prism, and the like. The main section of the prism is a triangle. The prism has two refractive surfaces, the angle between which is called the apex angle, and the plane against which the apex angle faces is the bottom surface.

According to the law of refraction, the prism passes through the prism and deflects the bottom surface twice. The angle q between the outgoing light and the incident light is called the deflection angle. Its size is determined by the refractive index n of the prismatic medium and the angle of incidence i. When i is fixed, the light of different wavelengths has different deflection angles. In the visible light, the maximum deflection angle is purple light, and the smallest is red light.

Penta Prism

Penta Prism

Machining indicators for high-precision right-angle prisms include a 90-degree angle, a tower difference, and a 45-degree angle. The tower difference is the non-parallelism of the edge of the prism and the reflecting surface. The processing of the 90 degree angle utilizes high-precision cubes to achieve batch processing, and the yield of the products is also very high. In order to obtain a satisfactory tower difference, at present, the conventional method in China is to use a 45-degree high-quality optical adhesive to process the finished product in batches, and then check out the finished product that meets the high precision, and then continue the batch processing in the unqualified batch, and then check out. Qualified products that meet high precision, which is time consuming and low in yield; or manual one-piece repair to achieve the required accuracy, the operability is poor, and the efficiency is not high.

In the batch processing of high-precision prisms, the angle is qualified but the surface finish is not up to the requirement, or the 90 degree is acceptable but the tower difference is unqualified. The reason is that it is easy to damage the surface by repeating the photo-adhesive processing. One-piece hand repair can improve the surface finish and improve the yield of finished products for a single piece, but it is necessary to design a set of tooling to solve the difficulty of hand repair. As shown in FIG. 8 , the existing method for modifying the prism tower is to protect the facet of the prism I from water and wipe the large surface 12 to be placed on the pad, and place four glass carriers around the prism. 11 to protect. The pad is surrounded by the strips, and the gypsum is injected into the wall to be solidified. After a few hours to confirm the solidification, the tooling is removed from the backing plate, and the large surface of the prism 12 and the plaster around the working surface of the glass carrier 11 are treated with a knife. Carefully remove the depth of about 2, then apply the protective wax evenly on the plaster around the prism to protect it from water. Then use a soldering iron to carefully polish the protective wax so that it is not higher than the large face of the prism and the working surface of the glass carrier. The large face of the prism is then sanded and polished. After the tower is modified, the gypsum is removed, and the prism is removed from the lower plate of the tool; the prism is carefully cleaned after the lower plate. It can be seen that the existing prism tooling operation process is cumbersome and inefficient, and the most fatal defect is that it will cause damage of 45° angle and cannot be repaired, and the polished surface finish cannot be completely guaranteed.

The main application areas of prisms:

1. Commonly used digital devices: cameras, closed circuit televisions, projectors, digital cameras, digital camcorders, CCD lenses and various optical devices

2. Science and technology: telescopes, microscopes, level gauges, fingerprints, gun sights, solar converters and various measuring instruments

3. Medical instruments: cystoscope, gastroscope and various laser treatments

Our company processes various prisms such as right angle prisms, equilateral prisms, wedge prisms, and Penta Prism with different base materials. Please feel free to contact us if you have any needs.

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  • Tel: +86 431 8188 4163
  • Add: No.399 Bo Cai Road, High-Tech Industrial Development Area, Changchun, Jilin, China, Zip code 130012
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