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
NOTCH-4 |
NARROW
NOTCH-6 |
Laser attenuation:
Optical density (averaged over entire clear aperture) |
> 4.0 |
> 6.0 |
> 4.0 |
> 6.0 |
Spectral bandwidth:
Wavenumbers between OD 0.3 or 50% transmission points, cm -1 |
< 500 |
< 350 |
Spectral edgewidth:
Wavenumbers between OD 0.3 and 4.0 points, cm-1 |
< 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:
for CW-lasers, W/cm2
for pulse-laser ( t =10 ns), J/cm2 |
10
0.5 |
Filter clear aperture:
Standard aperture,mm
Maximal aperture, mm |
25.4
70 |
Environmental stability:
Guaranteed durability, years
Temperature working range, °C
Atmosphere humidity stability at 35 °C, %
Allowed Thermal Shock, °C |
1
from -50 to +50
98
± 60 |
| Materials of substrates: |
Optical glass or fused silica |
|
Fig. 1 Typical transmission curves of the Notch-4 filter for 633 nm and
Narrow 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.
For quotation and delivery please fill in our request form.
