Gentec-EO Accessories for Beam Diagnostics - Manual (Page 9)

Accessories for Beam Diagnostics Revision 1.2 9
2.2. ND FILTERS ( < 1W ATTENUATION)
Gentec-EO offers various SM1 threaded absorptive Neutral Density (ND) filters that can be stacked directly on the
aperture of the Beamage-3.0 camera via a SM1 to C-mount adaptor. Subsequent filters can be stacked directly
on each other. These filters have the ability to equally reduce the intensity of all wavelengths without affecting the
wavefront of the beam or distorting the image. The attenuation is wavelength dependant see figure5. An empty
SM1 threaded filter holder is available for those who would like to use their own ND filters with their camera. It
holds 25 mm wide filters. Each filter and each holder comes with a SM1 to C-mount adaptor. Sets of 3 filters or 6
filters are also available.
Table 3: Neutral Density Filters Specifications
Spectral Range 400 nm – 650 nm
Filter Diameter 25 mm Ø
Clear Aperture 22.5 mm Ø (90% of diameter)
Dimensional Tolerance +0.0/-0.25 mm
Optical Density Tolerance ±5%
Parallelism < 10 arcsec
Transmitted Wavefront Error < λ/10 at 633 nm
Surface Flatness < λ/4
Surface Quality 40-20 Scratch-Dig
Maximum Power 1 W
Damage Thresholds 100 W/cm
2
or 3 J/cm
2
Data specified at 633 nm
Table 4: Available Products Characteristics
Model P/N Description
Optical
Density
@ 633 nm
Equivalent
Attenuation
Transmittance
@ 633 nm
Substrate
Substrate
Thickness
ND0.5 201094 ND filter 0.5 (1/3.16) ~32% NG4 ~0.91 mm
ND1.0 201045 ND filter 1.0 (1/10) ~10% NG4 ~1.89 mm
ND2.0 201046 ND filter 2.0 (1/100) ~1% NG9 ~1.40 mm
ND3.0 201047 ND filter 3.0 (1/1000) ~0.1% NG9 ~2.11 mm
ND4.0 202600 ND filter 4.0 (1/10 000) ~0.01% NG9 ~2.83 mm
ND5.0 202601 ND filter 5.0 (1/100 000) ~0.001% NG9 ~3.55 mm
NDSET-6 202605 Set of all 6
filters
See above - See above See above See above
NDSET-3 202606 Set of 3
filters (ND1,
ND2, ND3)
See above - See above See above See above
ND-H Call ND filter
holder
- - - - -
Warning
When using multiple ND filters, it is necessary for the light to pass through the less
attenuating filter first. For example, if you wish to have a 1/10 7 (ND 7.0) attenuation ratio,
you need to put the ND 3.0 on the front and then the ND 4.0 filter between the ND 3.0 filter
and the Beamage-3.0 camera.