Holographic Notch and Narrow Notch Filters

Download Holographic Notch and Narrow Notch Filters Datasheet (PDF, 84 KB)
Holographic notch filters (HNF)

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  from -50 to +50 
Atmosphere humidity stability at 35 °C, %  98 
Allowed Thermal Shock, °C ± 60
Materials of substrates: Optical glass or fused silica


Typical transmission curve of the Notch-4 filter for 532 nm


Typical transmission curve of the Notch-4 filter for 633 nm


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.