A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. Dichroic filters can filter light from a white light source to produce light that is perceived by humans to be highly saturated (intense) in color.
There are substrates which are coated with thin-films to acquire the desired transmission and reflection characteristics across the spectrum. They are often used as color filters (both subtractive and additive). They are slightly sensitive to angles but are much more forgiving than interference filters.
| ATTRIBUTE | SPECIFICATIONS |
| DIAMETER TOLERANCE | +0.1, -0.1mm |
| thickness tolerance | +0.1, -0.1mm |
| parallelism | < 1 arc minute |
| CLEAR APERTURE | >90% |
| transmitted wavefront, p-v | λ/4 @632.8nm |
| angle of incidence | 0 degree |
| SURFACE QUALITY | 60/40 scratch and dig |
| transmission | T ave > 90% |
| reflection | R ave > 98% |
