An optical bandpass filter is an optical filter that selectively transmits a specific range of wavelengths of light while blocking all other wavelengths. Bandpass filters are typically characterized by their central wavelength, bandwidth, transmission, and blocking.
While the passband often refers to the theoretical filter performance derived from design specifications, Semrock prefers to use manufacturable specifications which describe the actual filters as received by the customer.
Semrock uses a “manufacturable specification” approach to define the bandwidth of our bandpass optical filters. We believe this approach more accurately reflects the performance of the filter in an optical system.
As shown in the diagram, the filter spectrum (red line) will, on average, lie within the unshaded regions. The average transmission will exceed the specification Tavg in the Transmission Region, which has a certain center wavelength (CWL) and a width called the Guaranteed Minimum Bandwidth (GMBW). The transmission will, on average, lie below the blocking level specifications (OD) in the Blocking Regions.
Optical filters are used in diverse fields such as Spatial Biology, PCR, Quantum Computing, and Wearable Medical Devices, most of which rely on the fluorescence emitted by specially designed molecular probes.