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 23 C, and deviations from this value in the range of -60 C to +60 C 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 10 C, so temperatures significantly different from this will affect the effective central wavelength of the filters.
For example, at an ambient temperature of 0 C, an filter with specified central wavelength 6556Åwill have an effective central wavelength of 6553Å.