Chapter 7: Technical overview 107
Bandpass (BP)
filters
A BP filter transmits a relatively narrow range or band of light. BP
filters are typically designated by two numbers. The first number
indicates the center wavelength and the second refers to the width
of the band of light that is passed. For example, a 500/50-BP filter
transmits light that is centered at 500 nm and has a total
bandwidth of 50
nm. Therefore, this filter transmits light between
475 and 525
nm.
The performance of an optical BP filter depends on the optical
transmission. Sample transmission curves are shown in the
following figure. A filter with a narrower (steeper) transmission
curve generally yields higher performance. The transmission
specifications depend on the construction of the filter.
Bandpass
Wavelength (nm)
% Transmission
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