Bifrost Continuously Variable Bandpass Filters for Image Sensors

Charged-couple device (CCD) and complementary metal oxide semiconductor (CMOS) sensors are the most common types of image sensors. They work by converting incident radiation into electrical signals that produce the image.

In order for these sensors to work successfully, they require a bandpass filter, which is the element that determines which wavelengths are allowed to pass through and which are blocked. Delta Optical Thin Film manufacture a range of bandpass filters for image sensors, and Bifrost Continuously Variable Bandpass Filters for Hyperspectral Imaging are our newest range.

Bifrost Continuously Variable Bandpass Filters

These variable bandpass filters are designed specifically for mid-size and full-frame CCD and CMOS image sensors. These filters provide high transmission and their size allows them to be used with smaller, yet robust image sensors.

One common issue with standard bandpass filters is that they feature a region where wavelengths that should be blocked aren’t completely and are still transmitted at low levels. Our filters are made to the highest specification and reduce the transmission outside of the passband to a suitable level for the application.

Our bandpass filters also have a higher transmission, large aperture, and excellent signal to background ratio, all of which are beneficial over standard ones.

Our range of Bifrost Continuously Variable Bandpass Filters are available in 3 specifications that are ready to test, the specification of these filters are:

  • Centre wavelength range 450 nm to 880 nm, bandwidth approximately 2% of centre wavelength, blocking range 200 nm to 1150 nm, transmission 60% to 90%, blocking level OD4, for sensor size 24 mm x 36 mm
  • Centre wavelength range 450 nm to 850 nm, bandwidth approximately 4% of centre wavelength, blocking range 200 nm to 1100 nm, transmission 70% to 90%, blocking level OD4, for sensor size 30 mm x 25 mm
  • Centre wavelength range 796 nm to 1084 nm, bandwidth approximately 1% of centre wavelength, blocking range 200 nm to 1150 nm, transmission >85%, blocking level OD4, for sensor size 32 mm x 18 mm

We can also develop and produce these bandpass filters to exact specifications for our client’s different applications. We have over 50 years of experience in manufacturing bandpass filters, if you would like some more information about the range of Bifrost Continuously Variable Bandpass Filters, please contact us.