PBS Prism

PBS Prisms

The polarizing beam splitter prism can split the incident unpolarized light into two perpendicular linearly polarized light. The P-polarized light passes through completely, while the S-polarized light is reflected at an angle of 45 degrees, and the exit direction is at a 90-degree angle to the P-polarized light. Both the P-polarized light and the S-polarized light are linearly polarized light, and the polarization directions are perpendicular to each other. This polarizing beam splitting prism is made of a bunch of high-precision coaching prisms. One of the prisms is coated with a polarizing beam splitting dielectric film on the hypotenuse. The transmission and emission parameters can reach more than 95%.

Polarization is an inherent property of light, and polarization state is an independent parameter of light. If you want to fully describe the properties of a light/beam, in addition to frequency/wavelength, amplitude/intensity, and propagation direction, you also need to describe its polarization state. The so-called polarized light means that the vibration direction of the electric vector (E) of this light has a certain law. The polarization state can be divided into: linear polarization, elliptical polarization (circular polarization in special cases).

For example, for linearly polarized light, its electric vector vibrates back and forth in only one direction. Non-polarized light, such as natural light, the vibration of their electric vector is random, neither in some same direction, nor has a fixed time correspondence (no fixed phase) when vibrating, so their vibration is Random, with no fixed rules. In the concept of polarized light, in order to describe the relationship between the vibration directions, for the most basic linearly polarized light (through which it can be combined into elliptical light, and vice versa), we usually use P light and S light to distinguish. Among them, P light represents linearly polarized light whose vibration direction is parallel to the incident surface, and S light represents linearly polarized light whose vibration direction is perpendicular to the incidence surface.

Wire Grid PBS

Wire grid PBSs are designed for applications using non-collimated light sources such as broadband white light sources. Wire Grid PBSs consist of a wire grid polarizer glued between two precise high tolerance right angle prisms. Each side of the beamsplitter is AR coated to provide an average reflectance of less than 0.5% on each surface. Furthermore, these beamsplitters maintain their contrast in the spectral range of 400-700nm and a large cone angle of ±25°.

High contrast even at large angles of incidence

Low chromatic aberration even at large angles of incidence

Ideal for non-collimated light source applications

The main difference between prism and grating:

The grating spectrum is a uniformly arranged spectrum, while the prism spectrum is a non-uniformly arranged spectrum, with different spectroscopic principles, refraction and diffraction.

The applicable wavelength range of grating is wider than that of prism. The shorter the wavelength of the prism, the larger the deflection angle, and the opposite of the grating.

The spectral levels of the grating overlap, and there is interference, which should be considered to be eliminated; however, this situation does not exist in the prism.

Combination of polarizing beam splitter prism and λ/4 wave plate

The polarization beam splitting device is combined with the λ/4 wave plate. If the polarization direction of the incident light is parallel to the incident surface, it can all pass through the beam splitter (the reflection component is 0), enter the measured surface through the λ/4 wave plate, and return to When passing through the λ/4 wave plate, the polarization direction of the light can be turned to pi/2 after passing through the λ/4 wave plate twice, that is, the beam is perpendicular to the incident surface, and is fully reflected back to the detector after passing through the beam splitter (transmission component is 0), and there is no energy loss, this structure is widely used in various interference systems.