Gentec-EO Accessories for Beam Diagnostics - Manual (Page 6)

Accessories for Beam Diagnostics Revision 1.2 6
2. ATTENUATORS
2.1. BDA-A-VAR - VARIABLE ATTENUATOR
The BDA-A-VAR is an easy to use variable attenuator equipped with 4 wheels, each one containing 3 filters and 1
empty space as fixed positions. The different filters have transmission factors ranging between 100% and
0.003%. With 256 possible configurations, this variable attenuator offers almost continuous attenuation from 0 db
to as much as 93 dB (Optical Density > 9). It is particularly useful to fully eliminate the side background lighting
when using photo detectors with high sensitivity.
The BDA-A-VAR has M6 holes on 3 sides for mounting versatility and has C-mount threads on both ends for
direct connection with the Beamage-3.0 beam profiling camera. This variable attenuator uses NG absorbing filter
glasses that have a clear circular aperture of 18 mm. All filters are non-parallel (4° angle between them) since it
helps suppressing unwanted back-reflection interference fringes.
Figure 1: BDA-A-VAR Variable Attenuator
Table 1: BDA-A-VAR Variable Attenuator Specifications
Maximum Attenuation 93 dB (0.00000005%)
Minimum Attenuation 0 dB (0%)
Maximum Power Density 1 W/cm
2
Maximum Energy Density 100 mJ/cm 2
Wavelength Range 350 nm – 2200 nm
Clear Aperture 18 mm Ø
Angle Between Filters 4°
Mounting Capabilities M6 holes on 3 sides, C-mount threads on
both ends
Part Number 201116
Table 2: BDA-A-VAR Wheels & Filters
Wheel 1 Wheel 2 Wheel 3 Wheel 4
dB Transmission dB Transmission dB Transmission dB Transmission
Filter 1 0 1 0 1 0 1 0 1
Filter 2 0.5 0.9 5 0.3 20 0.01 35 0.0003
Filter 3 1 0.8 10 0.1 25 0.003 40 0.0001
Filter 4 3 0.5 15 0.03 30 0.001 45 0.00003