What is an optical prism?
An optical prism is an optical element made of a transparent medium such as glass or quartz. It is a polyhedral material with a structure in which the incident and outgoing surfaces form an angle in order to disperse or refract light.
It is sometimes simply called a “prism. Prisms are used in many optical instruments, not only in the field of optics, but also in surveying, medicine, semiconductors, telecommunications, and many other fields.
Applications of Optical Prisms
Optical prisms are optical elements that utilize the refractive index of the medium. They are used in optical equipment and many other devices related to imaging, video, surveying, etc.
1.Optical instruments, cameras, and semiconductors
In addition to spectroscopic instruments and laser interferometers, specific products in the field of imaging and video include film cameras, digital cameras, VTR cameras, DVD camcorders, LCD/LCOS type LCD projectors, DLP projectors, image information processors (color sensors), 3CCD video camcorders, etc. The optical prism is an optical element that is used inside the camera. Optical prisms are elements commonly used to bend the optical axis inside cameras.
In the semiconductor and LCD fields, they are used in exposure devices for lighting systems and stage systems. They are also used in microscopes, binoculars, and other observation and observation equipment. In the field of telecommunications, these elements are used together with optical fiber to contribute to high-capacity, high-speed communications.
2.Measurement and Surveying
Optical prisms are used in measuring instruments, surveying instruments (surveying vessels), lightwave rangefinders, and other surveying applications, and are also applied to aircraft, ships, and rockets.
3.Medical Applications
One of the most important applications of optical prisms is in the medical field. In the medical field, optical prisms are used in medical equipment such as endoscopes. In particular, prisms with a polished surface dimension (effective diameter dimension) of less than 5.0 mm, called microprisms, are used. These optical elements play a major role in the realization of high-performance compact medical devices.
Principle of Optical Prisms
Optical prisms are optical elements that cause dispersion, declination, and total reflection of light by utilizing the fact that the refractive index differs depending on the medium. Materials used include general optical glass, low-thermal-expansion glass, quartz, Si, CaF₂, etc. All materials are transparent. All materials are transparent. Prisms have a structure in which the incident and reflecting surfaces are non-parallel, which causes the desired refraction or reflection.
Since the refractive index in the medium varies with the wavelength of light, the refraction angle, or the direction of light emitted from the prism, changes with wavelength. This phenomenon is called dispersion. The dispersion of light through a prism makes it possible to obtain a spectrum. In many optical instruments, optical prisms are used to change the direction of light passing through by using declination, i.e., refraction, to spectrate light of different wavelengths (change the direction of light) by using dispersion, and to align the direction of light (combining).
Types of Optical Prisms
There are various types of optical prisms depending on their shapes, such as right angle prisms, corner cube prisms, declination prisms, dove prisms, pentaprisms, porro prisms, dach prisms, diamond prisms, dove prisms, and beamsplitters. Some of them are composite elements with lenses formed on the prism exit surface. It is also important to note that even the same shape has different functions depending on the material and coating. Appropriate selection should be made according to the application.
1.Right Angle Prisms
One of the most typical types of optical prisms is the triangular prism. Shapes such as right-angled isosceles triangles and right-angled triangles with 30° and 60° angles are available. Suitable for beam deflection and retroreflection, they can change the light direction by 90° or 180° to emit light. Light can also be dispersed by adjusting the angle of incidence appropriately.
2.Dove Prism
A dove prism is a prism in the shape of a right-angle prism with a portion cut out of it. Total reflection can be used to produce an inverted image without deflection. These prisms are used as image rotators in various optomechanical systems.
3.Penta Prism
Penta prisms are prisms that deflect light rays by 90°. independent of the angle to the optical axis,
It applies to all transmitted rays of light. It is useful for applications where the direction of the prism cannot be precisely controlled.
4.Porro Prisms
Polo prisms are a type of upright prisms in which all reflective surfaces are totally reflective.
It has no light loss and is easy to process.
5.Corner Cube Prisms
Corner cube prisms are prisms that return the light path back to the incident direction by retroreflection, utilizing three times internal total reflection. The reflective surface may be coated with aluminum or silver. In surveying instruments, corner cube prisms are used to reflect lasers and calculate distances from the time taken for the light to travel.