Long Pass filter is the one in which the pass band is a wavelength range higher than the wavelength range that is blocked. Long pass filters pass all wavelengths longer than the cut off wavelength. Long pass filters include cold mirrors, colored glass filters, and thermo set ADC (optical cast plastic) filters.
| ATTRIBUTE | SPECIFICATIONS |
| material | Optical glass, fused silica |
| DIAMETER TOLERANCE | +0.0, -0.2mm |
| thickness TOLERANCE | +0.1, -0.1mm |
| CENTRATION | 5 arc minutes |
| CLEAR APERTURE | >80% |
| transmitted wavefront, P-v | λ/4 @632.8nm |
| SURFACE FIGURE: IRREGULARITY(N) | <0.5 fringe |
| SURFACE QUALITY | 60/40 scratch and dig |
| COATING | Surface 1: dielectric coating; Surface 2: MgF2 |
| transmission | >85% |
| Cut-on tolerance | 2% |
| cur-on slope | 3% |
| blocking | Optical Density, OD>2 |
