ALPHA OPTICS AO-31821S Gen 3 Image Intensifier Tube

The Alpha Optics AO-31821S is 18mm, Gen 3, high-gain, high photosensitivity Inverting Image Intensifier Tube encapsulated within a hard-surface insulating sleeve and suitable for passive night vision systems and goggles. The AO-31821S consists of a high-efficiency (GaAs) extended red photocathode on a twisted fiber optic output window; glass input window; micro-channel plate (MCP) current amplifier. The AO-31821S has a built-in high-voltage power supply with overload protection circuit which incorporates (ABC) automatic brightness control to provide constant output image brightness as light levels varies. The power supply also provides (BSP) bright source protection to guard the tube against exposure to high levels of light and autogating feature (optional) to protect the tube against exposure to high levels of light.

• Gen 3
• P43 Green Phosphor
• GaAs Photocathode
• 18 mm screen diameter

Specifications:
Photocathode Useful Diameter	17.5 mm
Photocathode Type	GaAs
Material of output window	FOE, inverting, concave R=40 mm
Phosphor	P43
Limiting Resolution, min	64 lp/mm
Luminous Sensitivity at 2856° K, min	1800 µA/lm
Radiant Sensitivity at 850 mm, min	180 mA/W
Gain, min	35000 – 80000 lm/lm **
Max. output brightness	2 – 14 cd/m2 **
E.B.I., max	0.25 µlx
Signal to Noise Ratio at 108  µlx, min	24
Input Current, max	20 mA
Input Voltage	2.0 ÷ 3.6 V
Weight, max	85 g
MTFF	10000 hours

Maximum allowable spots in each zone
Spot size, mm	Zone I – circle Ø 5.6 mm	Zone II – ring Ø 5.6 – 14.7 mm	Zone III – ring Ø 14.7 – 17.5 mm
More than 0.200	0	0	0
0.150 – 0.200	0	1	1
0.075 – 0.150	0	2	2