How does DayStar certify their specification numbers?
Posted on Apr 25, 2011, 1:17 amAuthor: Jen Winter
Where do we get these certification numbers we use?
At the DayStar Laboratory, we have designed and built a special spectroscopy stage scanner which allows us to more precisely measure the properties of each individual etalon crystal in inventory.
Each individual etalon crystal is batch-scanned to classify it as a candidate for use in a DayStar Filter. Our entire inventory of thousands of etalons has been batch scanned and inventoried with its specifications cataloged.
Each basic scan samples areas of 5mm in diameter and moves in X and Y to scan the aperture of each etalon. Each specimine receives 44 separate scan samplings which record transmission %, FWHM and Central Wavelength.
Each scan also tests for pinholes as well as the "fit" of the actual transmission curve vs. a mathematically perfect curve. The scanner uses temperature, known sample and line emitter calibration. The results have been corroborated by independent testing methods by the National Solar Observatory.
This preliminary scanning classification of etalon inventory allows for sorting of candidates which may later be fabricated into completed filter assemblies.
Secondary testing is required for PE grade etalon candidates. Additional scanning at 2mm sample size is performed on these candidates. In the 2mm aperture, more small scale imperfections can be detected, and more precise FWHM bandpass measurements can be made.
PE grade filters operating in research applications always require high resolution, 2mm sample size spectroscopy scans.
These high resolution scans characterize the PE grade etalon in a much higher detail than ever possible before. Through these scans we have learned more about FWHM uniformity and its relationship to uniformity in density and photographic exposures. We have learned more about how to maximize CWL uniformity, as well as about transmission as it affects the visual performance of each etalon.
The DayStar Filters etalon scanner has vastly improved the speed in which we can reliably manufacture filters. By advanced testing and qualification procedures, we are now able to qualify or disqualify to a much higher degree of accuracy, which etalons will make good finished filters and which will not.
While all filters must still be tested live on the sun, our qualification and "pass" rate is vastly improved from these test methods. We are also better able to provide fully qualified filters to our research clients; and to supply imaging clients with a more satisfactory product.