Case Study: UV Transmitter, Visible Blocking Filter

Case Study: UV Transmitting, Visible and Near IR Blocking Filter

Customer Challenge: A customer required a filter that would transmit in the UV but block in the visible. The filter also had to be very durable, in the assembly process, it would be extensively handled, glued, cleaned etc. Soft coatings were deemed unsuitable.

Vortex’s Solution: Many UV coatings are soft and mark very easily, however our state-of -the art sputtering processes ensure tough rugged coatings due to the inherent high process energy. The coating can withstand exposure to organic based adhesives, standard cleaning solvents, most abrading agents and resistance to temperature and humidity variations that may occur in the field of operation.

For this project we suggested the use of Schott UG11 glass which provides much of the visible blocking already (see black curve in Fig 1 above). We added a short pass filter coating and anti-reflection coating to block the leak in the UG11 (675 nm – 775 nm) but preserve the UV transmission . The performance from both coatings on a clear witness piece can be seen on the graph above in red. A graph of the finished parts spectral performance can also be seen in Fig 2.

The Outcome: This example highlights two things, firstly a viable solution is often found through a combination of substrate knowledge plus a suitable coating, at Vortex we are able to use our wide knowledge base to quickly propose a solution. Secondly, the benefits of magnetron sputtering over other deposition technologies, means we were able to provide a tough coating which easily survives the rigours of assembly and the instrument’s day to day environment. Vortex has an excellent reputation for being innovative and ability to generate cost effective solutions to optical problems.