Holographic Notch and Narrow Notch Filters
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Holographic notch filters (HNF) are state-of-the-art volume holograms that provide high laser attenuation in a very narrow bandwidth. They are ideal for laser spectroscopy. In Raman applications it is possible to collect both Stokes and Anti-Stokes data with tens of wavenumbers of the laser line.
HNFs are made by recording interference pattern formed by laser beams in a layer of dichromated gelatin held between two plate glasses. They have a number of advantages over dielectric interference filters that are made by vacuum deposition of several thin discrete layers with different refractive indices. Firstly, HNFs provide the attenuation in the narrower bandwidth without cutting the useful part of the spectrum in the vicinity of laser line. Secondly, they do not generate the secondary reflection band found in dielectric interference filters.
We produce a variety of notch filter types with excellent optical performance. According to parameter's change they can be divided into 4 different types shown below.
Tab.1 Types of notch filters.
NOTCH-4 NOTCH-6 NARROW NARROW Laser attenuation: > 4.0 > 6.0 > 4.0 > 6.0 Spectral bandwidth: < 500
< 350 Spectral edgewidth: < 250 < 120 Available wavelength range, nm 400-1200 450-1200 450-1200 Standard wavelengths, nm 441.6, 457.9, 476.7, 488.0, 514.5, 532.0, 568.2, 632.8, 647.1, 752.5, 785.0, 1064.0 488.0, 514.5, 532.0, 568.2, 632.8, 647.1, 752.5, 785.0, 1064.0 Laser damage threshold:
Filter clear aperture: 25.4 Environmental stability:
Materials of substrates: Optical glass or fused silica |
Fig. 1 Typical transmission curves of the Notch-4 filter for 633 nm andNarrow Notch-6 filter for 532 nm.
We believe Tydex's niche is the manufacture of custom made notch filters those are the most competitive against dielectric interference filters in performance and against the standard notch filters of such reference producer like Kaiser regarding the price.
So we recommend you to ask from us even 1 peace of notch filters with the specification differed from Kaiser's standards in terms of wavelength, filter size and angle of incidence.
Please also note volume discounts for standard filters starting from 3 pcs also can be of interest to you.
