Gen. 4 Night Vision Devices

Opticsplanet.com is proud to introduce 4th generation Night Vision Devices to our customers!

Why Generation 4?

While there are quite a few categories for which image intensifiers are tested, there are a few which are critical to top performance:

Photocathode Sensitivity: measured in µA/lm this criterion specifies the number of electrons released by the Photocathode (PC). PC response is always measured in isolation with no amplification stage or ion barrier (film). Therefore, tube data sheets (which always carry this “raw” figure) do not reflect the fact that over 50% of those electrons are lost in the ion barrier. While for most latest 3rd generation image intensifiers the photoresponse is in the 1800 µA/lm (2000 µA/lm for the latest Omni VI Pinnacle tubes), the actual number is more like 900 µA/lm. The 4th generation DOES NOT use ion barrier and while its “raw” photoresponse is the same as 3rd, the actual number is actually 100% higher.

Signal/Noise Ratio: this criterion is tied with EBI (equivalent background illumination) and illustrates the amount of interference (also known as “hazing” or “snow”) visible in extremely low light conditions. Since the absence of the ion barrier in 4th generation tubes allows all electrons released from the PC to reach the amplification stage, it yields greater S/N ratio and lowers EBI with amazing performance in extremely low light conditions and dramatically reduced “hazing” in low light.

Halo and High Light Level Resolution: Halo determines the glare effect with bright lights and is reduced dramatically in 4th generation image intensifiers because of their use of auto-gated power supply. The same system improves High Light Level resolution from 12 lp/mm in the latest 3rd generation image intensifiers to a minimum of 36 lp/mm.

In conclusion the 4th generation technology represents the biggest technological breakthrough in image intensification of the past 10 years. With significant improvement in contrast level and in performance under all light conditions, 4th generation represents top of the line performance on the night vision market.


DATA FOR F9800TF GEN 4 ITT TUBE

Performance Specification:  Tube Type F9800TF
Ion film barrier: n/a filmless

Photocathode Sensitivity

• Luminous (µA/lm) min. 1800
• Radiant .830 µm (mA/W) min. 190
• Radiant .880 µm (mA/W) min. 80

Halo max. 1.25

Burn-in Input current - Pre-test (max) 45
EBI, max (phot)  2.5 x 10-11
Luminance gain
2 x 10-6 fc (K)           40-70
Input current, mA, max 45
2 x 10-4 fc (K)          21-Jul
Input current, mA, max 45
1 fc (K)                    1.4-4.2
20 fc (K)              1.4-4.2

Resolution
Center (lp/mm, min) 64
Peripheral (2 points, lp/mm min) 57
High light level (lp/mm, min) 36

SNR (min) 26
The above data can be verified by contacting ITT Industries directly
 

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