Multilayer interference filters for the far-infrared and submillimeter regions.
The theoretical and experimental aspects of an alternative approach to the construction of interference filters for wavelengths greater than 80 microm are described. The filters consist of a number of thin plastic sheets with films of a high refractive index deposited onto one or both sides of each sheet. These are then heat bonded to form a self-supporting optical multilayer filter. Experimental results are presented for a number of filters produced in this way. Reflectances of the order of 90% have been measured for wavelengths as high as ~200 microm. By successive reflections from two or more such multilayers it is possible to produce efficient, narrow-bandpass filters with blocking over extended spectral regions. The possibility of the construction of other devices, including even narrower bandpass filters and wideband beam splitters, is also discussed.
Shao
J
J
Dobrowolski
J A
JA