Multiband and Multizone Filters and Their Applications

Optical filters are used to provide wavelength selectivity to photonics applications, typically transmitting specific wavelength bands to the desired destination (detector or receiver) and reflecting other wavelength bands to different destinations (or just blocking the bands entirely). In some applications (such as spectroscopy, telecom, and 3D cinema), it is necessary to select multiple signal bands at various wavelengths on the same optical path; therefore, optical filters with multiband (bandpass or notch) spectral performance are required. In other applications (such as machine vision, remote sensing, and earth observation), it is advantageous for various spatial areas (pixels) on the imager/detector to observe different individual spectral bands for multispectral imaging, or to order sorting functionality; therefore, optical filter arrays with multizone, spatially varying wavelength selectivity are required.

Jason Palidwar describes the needs for both multiband (spectral) and multizone (spatial) varying optical filters, as well as the challenges and various solutions to the design and manufacture of these multifunctional optical filters.