Case Study: Short Wave Pass Visible Dichroic Filter

Case Study: Short Wave Pass Dichroic Filter for 45 Deg. AOI

Customer Challenge: The customer needed a dichroic filter to transmit green and blue light and reflect red light. The light source was uncollimated which meant the split had to be successful for 45° but also +/- 7 °.

Vortex’s Solution: One of the big issues with dichroic filters is that polarisation occurs naturally. The associated split into S and P polarisation widens the transition zone between transmitter and reflector which is unwelcome. Vortex understand the Physics of this, and we were able to design a filter with a narrower transition zone. This was very much needed since the filter had to operate from 38° to 53°. Modern optical design software means we can study all of these effects carefully before any coating is done at the quote stage and propose a suitable acceptable performance. Small compromises often have to be made, but intelligent ones that result in a successful working instrument with some safety margins. A key strength of Vortex is our ability to work with the customer’s engineers and system developers to overcome hurdles. We have technical knowledge, real world experience and use all communication channels including teams and on-site visits to thoroughly understand the problems involved

The Result: The filter was manufactured after extensive customer consultation, using our state-of-the-art sputtering technology to the tolerance of +/-4 nm.  It was also vital to limit thermal drift, even when the filter temperature was raised to 100˚C, there was negligible movement of the edge position.