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7300nm (7.3μm) Infared Longpass Filter
7300nm infared longpass filter is an optical filter designed to transmit wavelength longer than 7300nm and block shorter wavelength. Coligh manufactures ir longpass filter.
- 50% Transmission Cut-on Wavelength at 7300 nm
- >80% High Transmission
- Broadband Blocking and Transmission
- Insensitive to Angle of Incidence
- Hard First-Surface Dielectric Coating
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Mid-IR Longpass Filter With 7300nm Cut-on wavelength Description
The 7300nm infrared long-pass filter produced by Coligh is an optical filter using multi-layer dielectric thin film interference technology. It is designed to transmit far-infrared light with a wavelength of ≥7.3μm, while strictly blocking stray light in the short-wave region.
- This filter has the characteristics of high transmittance in a wide band, with a transmittance of 80% or more in the range of 7.5-13μm, which is suitable for the acquisition of far-infrared thermal radiation signals.
- At the same time, the cutoff depth OD>=2 in the range of 400-7200nm, and the transmittance is less than or equal to 1%, which can effectively eliminate mid-infrared background noise.
7300nm (7.3μm) Infared Longpass Filter Technical Datasheet
| Parameter | Specification |
| Cut‑on Wavelength (50% T) | 7300nm |
| High‑Transmission Band | ≥ 80% @ 7500nm-13000nm |
| Blocking Region | 400-7200nm |
| Optical Density (OD) | OD ≥ 2 (T < 1%) |
| Substrate Materials | White glass, Sapphire, Silicon, Fused Silica, Zinc Selenide |
| Coating Type | Hard first‑surface all‑dielectric |
| Surface Quality | 80-50, 60‑40, 40-20 scratch‑dig (MIL‑PRF‑13830B) |
| Clear Aperture | ≥ 90% of full aperture |
| Available Diameters | Ø12.7 mm, Ø25.4 mm, Ø50mm, Ø100 mm or custom |
| Thickness | 0.5mm, 1.0mm or custom |
7300nm (7.3μm) Infared Longpass Filter Applications
- Trace gas detection
Sulfur hexafluoride absorption peak is 10.6μm, chlorofluorocarbon absorption peak is 8-12μm, sulfur hexafluoride and chlorofluorocarbon are key leakage gases in power equipment and refrigeration systems, but their far-infrared absorption peak is easily interfered by water vapor and CO₂ laser harmonics. This leads to decreased detection sensitivity. . The 7300nm long-pass filter can strictly cut off short-wave interference <7.3μm, transmit the 7.5-13μm target gas absorption band, and monitor power equipment leakage - Deep space observation
The far-infrared radiation of interstellar dust and planetary atmosphere carries information on cosmic evolution, but water vapor in the earth’s atmosphere will interfere with ground telescope signals, and non-target bands need to be filtered out. This filter can filter out the earth’s atmospheric absorption peak <7.3μm and focus on the deep space target band 7.5-13um. Capture weak cosmic radiation signals. - Industrial waste gas incineration monitoring
Industrial waste gas incineration requires monitoring the real thermal radiation of high-temperature flames greater than 8um, but short-wave radiation of carbon dioxide and visible light during the combustion process will cover up the effective signal and affect the evaluation of combustion efficiency. This filter can cut off short-wave interference <7.3μm and transmit 7.5-13μm flame thermal radiation signals. - Industrial furnace monitoring
The thermal radiation peak of aluminum liquid and copper liquid is at 8-14μm, but the short-wave radiation in the furnace will interfere with the accuracy of infrared temperature measurement and cause temperature control deviation. This filter can cut off short-wave interference <7.3μm and only transmit 7.5-13μm thermal radiation signals.
