High-Tech Filters and Polarizers/Waveplates
A filter is a special type of flat window that, when placed in the light path, selectively transmits or rejects a specific range of wavelengths (=colors).
The optical properties of a filter are described by its frequency response, which specifies how the incident light signal is modified by the filter, and can be displayed graphically by its specific transmission map.
Different types of customizable filters include:
Absorptive filters are the simplest filters in which the basic composition of the filter substrate or a specific coating applied absorbs or completely blocks unwanted wavelengths.
More complex filters fall into the category of dichroic filters, otherwise known as "reflective" or "thin film" filters. Dichroic filters use the principle of interference: their layers form a continuous series of reflective and/or absorbing layers, allowing very precise behavior within the desired wavelength. Dichroic filters are especially useful for precise scientific work because their precise wavelengths (range of colors) can be very precisely controlled by the thickness and order of the coatings. On the other hand, they are generally more expensive and more delicate than absorption filters.
Neutral Density Filter (ND): This type of basic filter is used to attenuate incident radiation without changing its spectral distribution (like full-range Schott filter glass).
Color Filters (CF): Color filters are absorbing filters made of colored glass that absorb light in certain wavelength ranges to varying degrees and pass light in other ranges to a greater extent. It reduces heat transfer through the optical system, effectively absorbing infrared radiation and dissipating the accumulated energy into the surrounding air.
Sidepass/Bandpass Filters (BP): Optical bandpass filters are used to selectively transmit a portion of the spectrum while rejecting all other wavelengths. Within this filter range, long-pass filters only allow higher wavelengths to pass through the filter, while short-pass filters allow only smaller wavelengths to pass. Long-pass and short-pass filters are useful for isolating spectral regions.
Dichroic filter (DF): A dichroic filter is a very precise color filter used to selectively pass a small range of colors of light while effectively reflecting other colors.
High-Performance Filters: Includes longpass, shortpass, bandpass, bandstop, dual bandpass, and color correction at various wavelengths for applications requiring optical stability and exceptional durability.
Post time: Oct-25-2022