Vacuum Ultraviolet Notch Filters
Product Announcement from Cascade Optical Corp.
Most of the band-pass filters are designed either by combining long-wave and short-wave pass filters (broadband) or by utilizing Fabry-Perot multi-cavity design approach (narrowband). In vacuum ultraviolet, below 200 nm where very few materials transmit design of efficient transmission band-pass filters is basically impossible. One solution is to utilize several band-reflection filters and use them as a multiple reflector filtering system where incident radiation is reflected from each reflection filter in the system, thus, resulting in exponential filtering of the out-of-band spectrum.
This multiple reflection system was used to examine the electric field of the earth. CIV has an emission line at 155nm. Four reflective notch filters were used to transmit and extinguish extraneous wavelengths or noise from the detection system. All, notch filters were fixed at 45º. Once a clean emission line was created Scientist observe the Zeeman Effect on this line to get a better understanding of the electromagnetic field of the earth. This was a NASA project our Scientists were heavily involved in.