IR-Cut Filters

20 Oct 2022

With superior transmission in the visible wavelengths, whilst blocking the UV and NIR wavebands either side, Knight Optical’s IR-cut filters are ideal for applications where a camera’s CCD or CMOS sensors detect NIR light which can alter the true colour of the image. By utilising an IR-cut filter within these systems, the NIR light cannot reach the sensor and therefore only visible light is detected and displayed in the final image. With sharp transitions between the transmission and reflection bands, our IR-cut filters ensure the unwanted IR light is removed from the system (via reflection) and therefore sustaining the colour integrity of the image.

Figure 1 - IR-Cut filter transmission graph

Coated on borosilicate glass, with a low thermal expansion, Knight Optical’s IR cut filters also have an AR coating on the rear surface to reduce unwanted reflections and improve the transmission between 420nm to 650nm.

Knight Optical have an inventory of IR-cut filters available for global delivery. Our stock currently consists of 5mm through to 50mm diameters or squares, all 1.1mm thick. If these do not meet your requirements, we can also provide our customers with custom dimensions (5mm to 400mm) with a quick turnaround.

Please find our specifications below for our catalogue components:

Material: Borosilicate or equivalent
Diameter: +0/-0.20 mm
Length/Width: ± 0.30 mm
Thickness: < 60-40 scratch/dig
Surface quality: Tmin > 94% @ 420-620nm, Tmax < 2% @ 700-1000nm
Transmission: +/-10nm
Wavelength accuracy: front surface hot mirror coated
Coating: back surface AR coated

Customised IR-cut filters are also possible as we know it is not one-size-fits-all

Fully customisable options are available upon request, including different thickness and customisation on the AR coating.

All filters are tested in our metrology department using our Cary 7000 spectrophotometer, and raw data and graphs can be provided to our customers, as well as dimensional reports.

Contact our technical account managers with your enquiries.