A dichroid prism is a device that divides the light flux incident on it into several with different wavelength ranges (colors). They are used in three-matrix video cameras and cameras, as well as in projectors for dividing images into RGB components.
They are constructed from one or more glass prisms with dichroic optical coatings that selectively reflect or transmit light depending on the wavelength of the light rays. Thus, certain surfaces within the prism act as dichroic filters .
Dichroid prisms are widely used in many areas of optical systems such as instrumentation, instrumental production, video-photo equipment, telescopes, radars, etc.
The ability of dichroic prisms to separate or connect the components of a ray of light is widely used in video-photo equipment. For example, in video cameras this makes it possible to use 3 photosensors with an image divided into three monochrome images R, G, B on each photosensor .
The principle of operation of the device is shown in the figure. A ray of light enters the first prism (A). The blue component of beam B is reflected from the coating of the low-pass filter (F 1 ), but transmits waves G and R with longer waves (lower frequencies of electromagnetic radiation). The blue ray inside the prism is completely exposed to internal reflection from the input plane of prism A and leaves it through the lower face. The remaining stream enters the second prism (B) and is separated by a second filter coating (F 2 ), which reflects red light but transmits shorter wavelengths. The red beam is also completely reflected internally due to the small air gap between prisms A and B. The remaining green component of the beam passes through the prism C. Used in LCD projectors .
See also
- Dichroic filter
- Full internal reflection
- Beam splitter
- 3ccd