Optical Filters

Featured Product from Shanghai Optics

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Optical filters selectively allow certain wavelengths of light to pass freely while blocking other wavelengths. Shanghai Optics manufactures a wide range of optical filters for engineering, scientific, and photographic applications.

Our hard coated optical filters are dichroic filters. They are composed of a single substrate with a dense hard coating. These hard sputtered filters are expensive to produce, but they have excellent performance and are ideal for applications where precision is of paramount importance. We use cutting-edge IBS technology to give our dichroic filters uniform dielectric coatings, and no adhesives whatever are involved in manufacture.  This ensures a quality product with a very long filter life.   Since they have only one substrate covered with a thin film, Shanghai Optics dichroic filters are much thinner than traditional coated filters and offer much higher transmission.

Traditional coated optical filters consist of a complex assembly of absorbing material, metallic layers, and interference coatings. These are primarily used for analytical instrumentation and laboratory equipment, as their environmental stability is intrinsically limited.

Both of these types of filters are also known as interference filters. They are wavelength-selective through interference effects at the thin film boundary.

Our colored glass filters consist of a simple glass substrate with dye injected in the manufacturing process. The absorption and transmission can be controlled by the concentration of the dye used and by the thickness of the filter. These absorptive filters are highly stable and less expensive than other options. The optical properties are also more limited.

Filters can also be divided into three other categories: shortpass, longpass, and bandpass filters. Shortpass filters block wavelengths longer than a certain cut off while allowing short wavelengths of light to pass through unimpeded. These include hot mirrors, heat absorbing glass, and IR cutoff filters. Longpass filters block shorter wavelengths of light, and transmit longer wavelengths. Bandpass filters transmit a certain wavelength range (known as the pass band) and block or restrict all others.  The pass band may be narrow (2-10 nm) or broad (50-80 nm). Bandpass filters are more angle sensitive than other types, so you will want to pay extra attention to mounting and setup if you use a filter of this type.

Both shortpass and longpass filters are sometimes referred to as edge filters.