平凹方形柱面镜

带通滤光片是一种通过一定范围内的频率并拒绝（衰减）该范围之外频率的装置，它用于选择性地传输一部分光谱，同时拒绝所有其他波长。

1.  Germanium (Ge)

Germanium (Ge) is the preferred lens and window material for high performance infrared imaging systems in the 8–12 μm wavelength band. Its high refractive index makes Ge ideal for low power imaging systems because of minimum surface curvature. Chromatic aberration is small, often eliminating the need for correction.

2. Silicon (Si) 

Silicon (Si) is grown by Czochralski pulling techniques (CZ) and contains some oxygen that causes an absorption band at 9 microns.To avoid this, material can be prepared by a Float-Zone (FZ) process. Optical silicon is generally lightly doped (5 to 40 ohm cm) for best transmission above 10 microns, and doping is usually boron (P-type) and phosphorus (N-type). After doping silicon has a further pass band: 30 to 100 microns which is effective only in very high resistivity uncompensated material.
 
CZ Silicon is commonly used as substrate material for infrared reflectors and windows in the 1.5-8 micron region. The strong absorption band at 9 microns makes it unsuitable for CO2 laser transmission applications, but it is frequently used for laser mirrors because of its high thermal conductivity and low density. Application as window, lens in the 1.5 - 8 um region; Mirror for CO2 laser and spectrometer applications.
 

ZnS MultiSpectral Under intense heat and pressure, defects within the crystalline lattice are virtually eliminated, leaving a water-clear material with minimal scatter and high transmission characteristics from 0.4 to 12 microns. This material is particularly well suited for high-performance common aperture systems that must perform across a broad wavelength spectrum.

Specifications:

Material: ZnS MultiSpectral
Diameter Tolerance: --------------------- +0.0, -0.1mm
Thickness Tolerance: -------------------- ±0.1mm
Clear Aperture: ---------------------------->85%
Parallelism: -----------------------------------3 arc minute
Surface Quality: ----------------------------80-50 scratch and dig
Wavefront Distortion: -------------------- λ /2 per 25mm @633mm
Bevel: -----------------------------------------Protective  (<0.2mm x 45° )
Coating: -------------------------------------- Optional （Uncoated, AR Coating, etc.）

4. ZnSe material

ZnSe is a preferred material for lenses, windows, output couplers and beam expanders for its low absorptivity at infrared wavelengths and its visible transmission. For high-power applications, it’s critical that the material bulk absorption and internal defect structure be carefully controlled, that minimum-damage polishing technology be employed, and the highest quality optical thin-film coatings are used. The material absorption is verified by CO2 laser vacuum calorimetry. Our quality assurance department provides testing and specific optics certification on request.

ZnSe is non-hygroscopic and chemically stable, unless treated with strong acids. It’s safe to use in most industrial field, and laboratory environments.

长波通滤光片适用于各种应用，如气体监测，温度，传感，热成像和运动传感等。长波通滤光片可阻挡较短波长并传输较长波长。 阻挡可以来自反射，吸收或组合。 带通中的透射可以通过第二表面上的增透膜涂层来增强。