Concepts in Tunable Spectral Filters
Imaging systems optimized for broad regions of the optical spectrum typically use one or more bandpass filters when closer spectral scrutiny is required. Conventional multilayer interference filters designed for either wide or narrow spectral bands can be arranged on a filter wheel to achieve discrete passbands. However, with multilayer coatings, the passband width (δλ) scales directly with the center wavelength (λ0) for each filter. Thus it is not possible to vary δλ independently of λ0 without physically altering the filter combination.
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