As one type of optical filter, double-pass filter (also known as transmission filter) is an optical device that can selectively transmit or reflect light in a specific wavelength range. It is usually stacked by two or more thin film layers, each with specific optical properties. It has high transmittance within two specific wavelength bands, and has blocking properties in other wavelength bands between these two bands.
1.Working principle of double-pass filters
The working principle of double-pass filter is mainly based on the interference effect of multi-layer film. When light enters the filter, it interferes between different film layers. By designing and controlling the thickness and refractive index of the film layer, it is possible to selectively transmit or reflect light of a specific wavelength.
Specifically, when the wavelength of the incident light matches the wavelength used by the filter design, the light of the same wavelength will be enhanced inside the filter through the interference effect, allowing it to pass through the filter. On the contrary, the light of different wavelengths will be destroyed by the interference effect and absorbed or reflected by the filter.
The double-pass filters
2.Characteristics of double-pass filters
Selective Transmission or Reflection
Based on design and material selection, double pass filters can selectively transmit or reflect light within a specific wavelength range.
High transparency
In the selected transmission band, the transmittance of the double-pass filter can reach more than 90%, which can accurately select to transmit or block specific wavelengths of light.
High efficiency performance
Double-pass filters can achieve high transmittance or high reflectivity, enabling them to effectively operate and adjust light in optical systems; at the same time, their performance changes little under environmental changes such as temperature and humidity, and they have good insulation and corrosion resistance, and can work stably for a long time.
Characteristics of double-pass filters
Narrow Bandwidth
Double-pass filters have a narrow bandwidth for light within a specific wavelength range, providing high spectral selectivity.
3.Applications of double-pass filters
Double-pass filters are widely used in many fields, such as:
Optical instrument applications
Double-pass filters are often used in optical instruments such as spectrometers, microscopes, and lasers to selectively filter out or pass light of specific wavelengths.
Used in optical instruments
Communication technology applications
Double-pass filters are used in the fields of optical fiber communication, optomechanical devices, etc. to improve the quality of communication. For example, in optical fiber communication systems, double-pass filters are mainly used to filter out light of specific wavelengths for transmission and multiplexing of optical signals.
Optical information storage applications
In optical storage devices, double-pass filters are mainly used to selectively read or write optical signals of specific wavelengths.
Surface enhanced Raman spectroscopy applications
Used in surface enhanced Raman spectroscopy, double-pass filters obtain Raman signals of specific wavelengths by selective reflection or transmission.
In addition, double-pass filters are also used in life science fields such as biological microscopy and fluorescent probe detection, which can achieve more accurate detection and observation.
Final Thoughts：
By working with professionals at ChuangAn, both design and manufacturing are handled by highly skilled engineers. As part of the purchasing process, a company representative can explain in more detail specific information about the type of lens you wish to purchase. ChuangAn’s series of lens products are used in a wide range of applications, from surveillance, scanning, drones, cars to smart homes, etc. ChuangAn has various types of finished lenses, which can also be modified or customized according to your needs. Contact us as soon as possible.
Post time: Feb-14-2025
