Development of a wavelength scanning laser calorimeter

The design and construction of a wavelength scanning laser calorimeter, for the measurement of absorptance in optical coatings, are described. Preliminary measurements of the absorptance of narrowband spectral filters are presented and are used to illustrate the versatility of the instrument in terms of its large spectral range and sensitivity. Results lead to the conclusion that both materials (cryolite and zinc sulfide) used in the preparation of the coatings contribute significantly to the absorptance of the filters and that interference effects in the substrate must be taken into account, at least at the central wavelengths of the passband region.