Polarizing beamsplitters are optical devices typically used to split light into two separate polarized beams, although they can also be used in reverse to join two beams into one. They have applications in many fields, including laser, semiconductor and phototonics instrumentation. Since they separate light by polarization they are often used to transmit p-polarized light while reflecting all s-polarized light in a different direction. Shanghai Optics manufactures cubic beamsplitters, plate beamsplitters, and lateral displacement beamsplitters. All our beamsplitters are made of high quality glass, with high surface quality to allow tight tolerance on all parameters.
Laser beamsplitters separate a laser beam into two sectors, and are usually meant to reflect part of a beam (either differentiated by wavelength or polarization). For laser applications cubic, plate, or lateral displacement beamsplitters are all possible options, and each of these can be custom-made for laser wavelengths.
If a simplified mounting is important and durability is key, we typically recommend cube beamsplitters. These beamsplitters are constructed from two right angle prisms, cemented together to form a cube. The thickness of the cement layer depends on the wavelength of light in the intended application. The inner surface of one of the prisms is coated with a partially reflective metal-dielectric coating.
The cube should always be oriented so that incident light enters the coated prism, so that energy passing through the optical cement is minimized. Entering through the wrong side will cause more than triple the amount of energy to pass through the delicate cement layer. If used in this way with high power light, the cement may degrade over time. We place a reference mark on the ground side of the coated prism to make it easy to orient your cube correctly.
Cubic beamsplitters have no beam shift and can be easily integrated with 0 degree angle of incidence. The reflected and transmitted optical path lengths will be equal. These devices, as compared to other options, allow you to shorten the optical path of a system. Their only disadvantages are the heavy construction—each piece is solid glass – and the fact that they are both difficult and expensive to make in large sizes.
Plate beamsplitters, on the other hand, are lighter and less expensive, and they can be easily manufactured in any size. They consist of a flat, thin glass plate, with a coating on the first surface of the substrate. The reflected and transmitted optical paths will have different lengths, and there will be a beam shift in transmitted light. Although they are often designed for a 45 degree angle of incidence, setup may require extra alignment time.
If an incident beam should be divided into two displaced parallel beams, you will want to use a lateral displacement beamsplitter. Our precision lateral displacement beamsplitters, which consist of a rhomboid prism cemented to a right angle prism, ensure that exiting beams have no more than 30 arcsec deviation from parallel. A multi layer anti reflection coating on both entrance and exit faces can provide increased efficiency.
We are able to produce custom beamsplitters tailored to your application, wavelength ranges specification, and tolerance levels.