Product Descriptions:
| Characteristics: | 635-40nm Bandpass Filter |
| Central Wavelength (CWL): | 635+-5nm |
| Full Width at Half Maximum（FWHM): | 40nm |
| Peak Transmittance(%) : | ≥92% |
| Dimension(mm): | Customized |
| Thickness(mm): | Customized |
| Substrate: | Ultra-clear glass,K9,BK7,B270,D2637T, Quartz Glass(Fused Silica) or other specified. |
| Remark：Spectral range:380-1100nm *Customized capability: 380-2500nm, stock for 10nm intervals. **Common for 86x86mm, 80x80mm, other can customized, max. 300x300mm *** Thickness available: 0.21、0.3、0.55、0.7、1.0、1.1、1.5、1.8、2.0、3.0mm…etc | |
Measured Spectral Graph – 635-40nm Bandpass filter:
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| Picture 1: 635-40nm Spectral Graph measurement |
What is typical application for 635nm bandpass filters?
Typical application for 635nm bandpass filters is very broad, include Laser Rangefinders, Proximity Switches and Photoelectric Switches …etc.
Typical Bandpass filters solution for Laser Rangerfinders from Liyuan Optoelectronics:
| PartName | Pictures | Spectral measure | Application Features |
| 650nm Red Light Narrowband Filters |  |  | Mostly used in consumer-grade handheld rangefinders (e.g., for home improvement). Visible red light facilitates aiming; typical bandwidth is 15–25nm, peak transmittance >80%. Low cost and easy to operate. |
| 850nm NIR Narrow Bandpass Filters |  |  | Commonly used in phase-shift ranging. Compatible with silicon detectors, with less solar background interference than visible light. Bandwidth 8–15nm, cutoff OD4, suitable for medium-range industrial measurement. |
| 905nm NIR Narrow Bandpass Filters |  |  | Mainstream for pulsed ranging and LiDAR. Eye-safe, long detection range, bandwidth 5–10nm, peak transmittance >90%, excellent at suppressing background light in strong outdoor sunlight. |
| 940nm NIR Narrow Bandpass Filters |  |  | Similar performance to 905nm. Used in some scenarios to avoid co-frequency interference at 850/905nm, suitable for security and automotive auxiliary ranging. |
| 1550nm NIR Narrow Bandpass Filters |  |  | Extremely high eye-safe threshold, allowing high-power emission for long-distance surveying, aerial and satellite ranging. Usually matched with InGaAs detectors, bandwidth 5–10nm, designed for low temperature drift. |
What is key parameter when choose for right bandpass filter?
When selecting a bandpass filters, the center wavelength (CWL) will be one of key parameter to be designated, with a tolerance of generally +/-5nm or +/7nm which depend on the user inquiry. Secondly,Peak and Average Transmittance,e.g 90%,95%…etc. higher transmittance might need Anti-reflective(AR) coating.Shenzhen Hengda Liyuan Optoelectronics introduced advanced optical technology that apply depositing nanomaterials through ion-assisted evaporation onto a multilayer hard film in a high vacuum environment which coating layer is firm and has good tightness, and small bandwidth drift.
