Bandpass Filter

Band-pass filter (BPF) is a crucial optical component whose core function is to selectively transmit light signals within a specific wavelength range while significantly attenuating or blocking light outside this range (including shorter wavelengths and longer wavelengths). It serves as a core device for precise optical signal extraction and interference suppression in various fields such as optical detection, imaging, and communication.

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Type：

Narrow-Band Filter, NBF

FExtremely narrow FWHM (usually FWHM < 10nm, down to below 0.1nm in some high-precision scenarios).
Applications: Fluorescence spectroscopy, LiDAR, atomic spectrum detection (e.g., screening of mercury lamp characteristic spectral lines).

Wide-Band Filter, WBF
Features: Wider FWHM (usually FWHM > 50nm), allowing light in a wider wavelength range to pass, balancing the needs of "screening" and "light transmittance".

Applications: Color photography lenses (e.g., compensating for light intensity in specific bands), machine vision lighting systems, infrared thermal imaging (screening specific infrared bands).

Parameter List:

Product name	Bandpass filter
CWL	245-1064nm
FWHM	5nm；10nm; 20nm; 30nm, 50nm or customized
Blocking wavelength	200-1200nm or customized
Optical density:	OD3; OD4; OD5; OD6
Diameter&Tolerance	0.5-600±0.02mm
Clear Aperture	≥90%
Thickness&Tolerance	0.3-50±0.02mm
Surface flatness	1/2，1/4，1/8，1/10λ
Surface quality	10-5/20-10/40/20/60-40/80-50
Beveling	45°×0.2mm
Coating	Hard Coated

Difference from Other Filters

Filter Type	Function	Application Example
Band-Pass Filter (BPF)	Allows light in a specific wavelength range to pass, blocks other wavelengths	Fluorescence imaging, WDM communication
Low-Pass Filter (LPF)	Allows light shorter than a certain cut-off wavelength to pass, blocks long waves	IR cut-off filter (blocks infrared light in cameras)
High-Pass Filter (HPF)	Allows light longer than a certain cut-off wavelength to pass, blocks short waves	Near-infrared imaging systems (blocks visible light, retains infrared light)