Principle and classification
A prism is an optical element that deflects light according to a specific angle between the emitted light and the incident light. The prism in the optical system mainly realizes the functions of turning the light path, turning the image, inverting the image and scanning. The prisms used for beam steering can generally be divided into reflective prisms and refracting prisms.
The reflecting prism is made by grinding one or more reflecting surfaces on a piece of glass, using the principle of total reflection and coating technology. If the angle of the light inside the prism when it reaches the surface is greater than the critical angle for total reflection, it will produce Total reflection, all light will be reflected back to the inside; if the incident light cannot be totally reflected, a metal reflective film, such as silver, aluminum or gold, must be plated on the surface to reduce the light energy loss of the reflective surface; In addition, in order to increase the amount of light transmitted by the prism and reduce or eliminate the stray light of the system, the incident surface and the exit surface of the prism will be coated with antireflection coatings with a specific spectral range. In the optical system, the reflective prism is mainly used to change the direction or position of the optical axis of the optical system, change the imaging direction as a revolving system, and realize light splitting and image combining.
There are many types of reflective prisms and different shapes. They can be roughly divided into simple prisms (such as right-angle prisms, isosceles prisms, pentagonal prisms, dove prisms), roof prisms, cone prisms and compound prisms.
The refraction prism is based on the principle of light refraction. The working surface is two refraction surfaces, the intersection of the two refraction surfaces becomes the refraction edge, and the dihedral angle between the two refraction surfaces becomes the refraction angle of the refraction prism, represented by α. The angle between the outgoing light and the incident light is called the deflection angle, which is represented by δ. For a given prism, the refraction angle α and the refractive index n are fixed values, and the turning angle δ of the refraction prism only changes with the incident angle I of the light.
Prism technical indicators
- Coating characteristics
Usually, aluminum and silver reflective films are plated on the reflective surface of the prism to improve the light reflectivity, and antireflection coatings are plated on the incident surface and the exit surface to increase the light transmission of the prism and reduce or eliminate the stray light of the system, including UV, VIS, NIR , SWIR different bands. Common coating characteristics are shown in the figure below
- Steering characteristics
Prism can realize the function of turning light path and turning image. Different prisms achieve different turning angles of light beams and images, and the same prism has different usages and different turning angles.
Application and selection of prisms
Huasen Optics can provide various standard prisms in stock, such as K9 glass or UV fused silica right-angle prisms, K9 pentagonal prisms, K9 prisms, suitable for different wavelengths such as ultraviolet, visible light, near-infrared, and different sizes of quasi-precision and high-precision. Granville prism, K9 roof prism, K9 corner reflector, UV fused silica corner reflector, wedge prism, etc. The surface coating of the product includes aluminum, silver, gold reflective film, antireflection film, nickel-chromium protection, black paint protection, etc.
While we provide a variety of prism standard products, we can also provide you with prism customization services according to your actual needs, such as the change of prism size, the improvement of parameter indicators, and the change of coating requirements.