Multilayer dielectric thin films with alternating refractive indices are coated in multiple layers to utilize optical interference for wavelength selection. By precisely designing the optical thickness and number of layers—from just a few to several hundred—it is possible to realize various spectral characteristics such as steep edges, wide passbands, and high blocking regions. These filters can be fabricated on substrates of various geometries, from flat plates to curved or parabolic mirrors, making them suitable for complex optical assemblies.
Capabilities
- High extinction ratio and excellent angular stability over a wide wavelength range
- Customizable edge steepness, passband width, and blocking level
- Available in plate and cube formats
- Supports both longpass (transmit longer wavelengths) and shortpass (transmit shorter wavelengths) designs
Applications
- Beam combination or separation in laser systems and optical instruments
- Color separation in digital projection and illumination systems
- Fluorescence and Raman spectroscopy (excitation/emission separation)
- CCD/CMOS imaging and optical sensing systems
- Lamp reflectors and precision optical mirrors
Example Filter Types
- Wide Passband / Wide Blocker Filter: A shortpass-type dichroic filter characterized by a wide transmission region and wide blocking band.
- Longpass Filter: A longpass-type dichroic filter that transmits longer wavelengths while reflecting shorter ones.
- Bandpass Filter: A filter combining shortpass and longpass coatings to transmit only a specific wavelength range.
