Spectral filters are optical elements that are difficult to characterize in transmission using a standard interferometer. Because these elements behave differently depending on the wavelength, they tend to be unmeasurable using an interferometer with a fixed working wavelength (usually 633 nm). For dichroic beamsplitters, characterization is even more complex because they generally require characterization both in reflection and in transmission which in turn requires at least 2 different characterization wavelengths. For these optical elements the use of a simple interferometer cannot be an adequate answer.
To address this specific needs, Imagine Optic just released an interferometer-like instrument, the R-Flex LA based on a Shack-Hartmann wavefront sensor associated with multispectral illumination, and a polarization-controlled collimator with a diameter ranging from 25 to 150 mm.
This innovative solution allows for the characterization of filter or dichroic beamsplitters in transmission or in reflection with a double path optical configuration (see fig1) with lambda/100 accuracy. Furthermore, measurement can be done at any wavelenght between 400 and 1100 nm. A large choice of source is available from our website; DIY and custom sources may also be used – make sure to use a monomode fiber FC-APC connector for input. Lastly, polarization can be perfectly controlled thanks to polarization-maintaining fiber.
Using the R-Flex LA, any filter can be characterized in transmission in the spectrum range where the filter is transmissive and in reflection in the spectrum range where it is reflective.
If you’re interested in finding out more about our Optical Metrology Systems, you can reach us at sales@imagine-optic.com or through the contact form (red enveloppe on the side).