Short Wave Pass Filters what are they?

May 28, 2024

Short Wave Pass Filters or SWP filters are a commonly used building block in optical instrument design.

As the name suggests, they allow light of shorter wavebands to pass through whilst rejecting shorter bands. They are used in all parts of the spectrum.

Fig 1 below shows a visible short wave pass filter, it will allow visible wavelengths from 400-720 nm to pass through, longer wavelengths from 730-1200 nm will be blocked. A SWP filter is often defined by its 50% Transmission point, in this case 730 nm. The steeper the edge requirement the more expensive it is to manufacture.

Another example below is a shortwave pass filter for the SWIR range, 1.4-2.65µm being transmitted and 2.75-7.5 µm being blocked. The 50% point is 2.7 µm.

Vortex design and manufacture a wide range of customer SWP filters for visible and IR use from 350-5000nm, contact us today to discuss your requirements. Enquiries@vortexoc.com, www.vortecoc.com