| • Why are PE filters so expensive?
- PE etalon crystals are not MADE. They are mined, discovered and processed. No process exists to improve the uniformity of a mica crystal. Non-uniformities are the result of minute fluctuations in the index of refraction within the mica due to chemical abundances when the crystal forms in the ground.
- Only the highest grade of mica in the world can yield PE grade etalons.
- Top grade mica costs thousands of dollars / lb in raw form.
- >80% of mica is wasted in the cleaving process to make _any_ etalon; SE and PE grades included.
- All viable cleaved mica is processed with coatings to increase narrow band peak etalons, but uniformity is never altered or improved in the coating process. Â Mica which meets our stated PE grade standard is offered as available in PE grade filters.
• Aren't all PE grade filters perfect in uniformity?
- We wish perfect mica exists, but it does not.
- Our PE grade standard is already 26,000 times more accurate than the optical 1/4 wave standard.
- Unfortunately, sub-atomic sized imperfections in chemical composition of naturally occurring mica can cause fluctuations in density or CWL and will always exist in the real world
- In a bandpass as narrow as >0.1nm (>1.0Ã), a sampling now exists which reveals these sub-atomic scale variations enough to be detectable from time to time.
• For the asking price of this filter, it should be perfect!
- Define perfect. To how many decimal points? To the micron? To 1/100th of a wave? To 0.05Ã, to the atomic level? How about to 1/10th the radius of a hydrogen atom? That is our standard.
- Daystar is not advertising or stating that any filter is or can ever be made that is "perfect".
- Daystar offers filters which meet a stated specification which is measured using independently verified special, purpose built equipment to the best quality standards available.
• I have another filter that shows "better" views.
- Daystar warrants no product to be "as good as", "better than" or "as uniform as" any other filter which exists.
- Different filters may be manufactured through different means (such as the Lyot style filter or air spaced etalons, etc) ; in which case different principals of index of refraction apply.
- Daystar offers set, quantifiable uniformity standards; which it warrants all PE grade filters shall meet or be replaced or repaired.
- "Better" is a purely subjective term.
- Photographic images taken through a filter are not spectroscopic tools and are not quantifiable test data.
Daystar Filters is pleased to offer high resolution spectrographic scanning services for all our Quantum PE clients. Our purpose built, specially engineered spectroscopic testing equipment provides high resolution mapping of all new DayStar Filters we manufacture.
PE grade filters are manufactured and qualified to a spectral uniformity in CWL (Central Wavelength) accuracy of ± 0.05 Ångstrom*. Our high resolution etalon mapping equipment offers qualification certified accurate by independent testing with etalon transmission sample sizes of 5mm or 2mm sample sizes with certification printouts available on new PE filter purchases.
Side-by-Side comparison:
Daystar uses specially produced test equipment which has been independently verified and tuned for precision and accuracy daily (sometimes hourly). Only 3 known sources worldwide posess equipment capable of quantitative analysis of sub angstrom spectroscopy outside of the Daystar Filters laboratory. Analysis from any of these sources is respected and always welcome. Owners are welcome to contact Daystar at any time with service concerns. Should filters sent for service meet or exceed stated specifications without flaw, filters will be returned to the owner in same or better condition.
*The mean peak wavelength of all 12 mm. dia. areas shall be within ± 0.05 ångström of the full aperture wavelength measurement.
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