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Change due to temperature

Temperature changes affect a filter's performance due to thermal expansion and contraction of the materials used to construct them. Most filters are designed and specified for operating at 23C, and deviations from this value in the range of -60C to +60C will produce peak wavelength shifts approximately linear with temperature. The exact shift coefficient will depend on the particular design wavelength of the filter, and, typically, ranges between 0.2Åand 0.3Å per C at 4000Åand 6500Årespectively. Bandwidth and peak transmission changes observed are relatively minor, of the order of 0.01Å per C and 0.013Å per C respectively.

The interference filters were specified for working at 10C, so temperatures significantly different from this will affect the effective central wavelength of the filters.

For example, at an ambient temperature of 0C, an filter with specified central wavelength 6556Å will have an effective central wavelength of 6553Å.

Tue Aug 15 16:42:46 BST 1995