Stories & Features
Limitations in current systems for accurate measurement of spectral performance constitute a challenging aspect of filter design and validation. Improvements in relevant technologies are being brought to bear, however, and progress is being made in that respect. For example, our Semrock optical filters team has recently completed development of the Kola Deep™ Spectral Measurement System, so named after the Kola Superdeep Borehole. This proprietary instrument addresses shortcomings in conventional and advanced metrology systems to provide accurate measurement of optical blocking to OD 9 and beyond, and to resolve edges steeper than 0.2%, relative to the edge wavelength, of the transition from 90% transmission to beyond OD 7. Another improvement is that the instrument performs across the UV, visible, and IR light spectra. It is robust and easy to operate, allowing its use in standard high-volume optical filter production lines without the need for an attending specialist.
At least three key benefits accrue from development of the Kola Deep Spectral Measurement System. First, it is now possible to easily assure that high-performance Semrock filters meet their spectral specifications. Before the development of this instrument, several sophisticated methods were used to assure that specifications were met; these are effective but rely on indirect processes and are slower to complete. This new instrument allows the measurements to be made directly, which simplifies and speeds the production process. The second key benefit is the enabling of further innovation in filter design and production. For example, the ability to accurately measure steeper spectral edges may permit the development of improved instrumentation filters for biochemical analysis. The third benefit is that the ability to accurately measure deeper blocking may allow systems designers to choose Semrock filters with confidence, knowing that even modest sources of undesired light are adequately suppressed in the optical system by truly high OD blocking.