Optical Surfaces Ltd. reports on a technological development that has enabled them to produce a new design of athermalized beam collimator that offers stable and high performance over a wide temperature range.
Dr Aris Kouris, Sales Manager of Optical Surfaces Ltd, said: “Traditionally, beam collimators have a tendency to defocus when exposed to environments with large variations in temperature. It is a particularly difficult task to balance both field centering and defocusing without having to control the environment itself or resort to very complex, dynamic and generally expensive solutions. Our athermalized beam collimators are based on a uniquely modified off-axis mirror design incorporating INVAR elements and a new mechanical characteristic which when combined allows for 100% direct thermal compensation.. Unlike expensive dynamic options, this is achieved passively and adaptively in real time as thermal variations take place. As a result, high optical performance is maintained over a wide temperature range (+ 5 ° C to + 35 ° C).
Zero-expansion off-axis parabolic mirror
The stability and high performance of Optical Surfaces reflective beam collimators are further ensured by the use of a zero expansion off-axis parabolic mirror, manufactured to a surface accuracy greater than lambda / 10 pv. The optics inside the beam collimator are secured by the use of unconstrained brackets and are pre-aligned for optimum performance. The off-axis design of the Optical Surfaces beam collimators does not produce central obscuration thus ensuring highly efficient transmission. The fully reflective design of Optical Surfaces beam collimators is achromatic and with aluminum / magnesium fluoride coatings can operate from UV to infrared without adjustment. The use of zero expansion glass mirror substrates helps these beam collimators provide exceptional operational stability. Each system has an output port at a set distance from focus and a side platform. All Optical Surfaces beam collimators provide a 20mm field of view ensuring full compatibility with standard blackbodies.
The beam collimators manufactured by Optical Surfaces Ltd are contained in an aluminum housing with the possibility of attachment to an optical table. Alignment aids are provided to ensure correct beam aiming. An interferogram and an OPD card are supplied with each beam collimator manufactured by Optical Surfaces.
The company’s ISO 9001-2015 approved fabrication shops and testing facilities lie deep underground in a series of tunnels carved out of solid chalk. This provides an environment where the temperature is naturally thermally stable and the vibrations are extremely low. With such stable conditions, testing of high precision optical components and mirrors becomes quantifiable and reliable. In addition to these natural benefits, Optical Surfaces has invested in a wide range of test equipment and developed methods to ensure accurate and reliable testing.