Optical Filters _ Bandpass Filters
What are bandpass filters ?
Bandpass filters are optical filters that allow signals between two specific frequencies to pass, but that discriminates against signals at other frequencies.?
Here is a spectrum curve of bandpass filters :
What specifications are required for the bandpass filters ?
1.?Center Wavelength(CWL) : the midpoint of passband wavelength
2.?Full Width at Half Maximum (FWHM): the width of the transmitting region at half of the maximum transmission value
3.?Blocked Area :the wavelength band that you want to be blocked /rejected
4.?Blocking Value: optical density
5.?Peak Transmission (Tpeak): the maximum transmission of the filter?
Types of bandpass filters based on FWHM：
1.?Wide bandpass filter
2.?Narrow bandpass filter
When the FWHM is larger than 30nm ,we normally determine the filter as a wide bandpass. When the FWHM is smaller than 30nm,we determine the filter as a narrow bandpass.
Types of bandpass filters based on wavelengths:
1.?UV(ultraviolet) bandpass filters
2.?VIS (visible) bandpass filters
3.?IR (infrared) bandpass filters
Applications of bandpass filters:
1.?Medical
2.?Laser range/distance measurement
3.?Iris recognition
4.?Automotive sensor
5.?Industrial safety system
6.?Biotechnology
7. Fluorescence microscopy
Optolong Optics offers a wide variety of bandpass filters for UV , Visible , Infrared applications . The FWHM is from 3nm to 100nm or even wider than 100nm .?
More details of bandpass filters in Optolong Optics