Longwave pass dichroic Beam splitters also known as Long Wave Pass or Short Wave Pass Filters or combiners are used to separate or combine two different wavelength beams in a system. They involve both the longwave pass and the short wave pass. Longwave pass is when the transmittance for longer wavelength range is maximized while when the transmittance for the shorter wavelength range is maximized it is called short wave pass and they are mostly used close to angle 45°. The transmittance for a longer wavelength range is always higher than that for a shorter wavelength range, therefore it is very necessary to design the optical setup to use the Long Wave Pass dichroic Beam splitters for the applications where the light throughput is critical. Dichroic beamsplitters offer a splitting ratio that is dependent on the wavelength of the incident light. They are useful for combining/splitting laser beams of different colors and wavelengths. Dichroic beamsplitters are mostly used as light guiding optics, intended to reflect a specified wavelengths range, transmit a different specified wavelengths range at a specified AOI and an angle of 45°(45 degrees).
Splitting Of Long Wave Pass Dichroic Beam Splitters
A beam splitter is an optical device that splits an incident light into two, when a beam splitter is placed at an angle that is relative to the incident light, one of the beams is transmitted through the beam splitter while the second beam is reflected. This incident light can either be from a normal light source or laser light. To achieve beam splitting, it can be caused by the following factors. You can get variety of optical mirrors from Alpine research optics.
Beam Splitting By Wavelength
This is where dichroic Beam splitters function properly. This can be achieved with the use of the dichroic mirror. The word dichroic which translates to two colors explains the principle of dichroic Beam splitting through wavelength as the incident light is either transmitted or reflected depending on the Wavelength passing through the beam splitter. Dichroic Beam splitters come in two forms, either as a hot mirror or as a cold mirror. The hot mirror diverts IR away from a sensor behind the beam splitter while a cold mirror reflects the visible portion.
Beam Splitting By Polarizing
Another technique employed in beam splitting is by is optic polarization state. Unpolarized light can be splitter into two beams the s-polarized light beam and the p-polarized light beam, the S-polarized light beam is reflected while the p-polarized light is transmitted.
Beam Splitting By Intensity
When the surface of a transparent object is coated with a thin dielectric metallic coating, it helps to split light beams by their intensity. But the coating thickness determines the quantity of the light beam that will be reflected or transmitted expressed as the R/T ratio. In an ideal situation, the ratio of transmitted light to reflected light is 50:50 but with a very thick coating, the reflected light will be more than the transmitted light.
Features Of Long Wave Pass Dichroic Beam Splitters
- Multi-band dichroic filter with two transmission bands and one reflection band
- Resistant to damage from UV light and chemicals
- Dichroic filters function as long-pass filters with minimal absorption losses
- Durable hard coating allows easy handling and cleaning
- Their wavelength ranges from 425nm to 800nm
- Available in different shapes ranging from rectangular shapes to oval or oval shape
