Multi-bandwidth frequency selective surfaces for near infrared filtering: design and optimization

The design of sub-millimeter filters follows the design methods used in the microwave region. Exacting modal matching, integral equation or finite element methods can be used for design. A major difference though is the introduction of material parameters and thicknesses that may not be important in longer wavelength designs. This paper describes the design of multibandwidth filters operating in the 1-5 micrometer wavelength range. In this paper extensions based on further optimization and an examination of the specific shape of the element in the periodic cell are reported. Results from the design, manufacture and test of linear wedge filters built using microlithographic techniques and used in spectral imaging applications are presented.