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What is the best camera for Night Vision? Comparison of an image intensifier, SWIR and CMOS cameras.

There are quite a lot of options to see at night. It could be either a night vision device, a thermal imager or maybe an EMCCD camera. Unfortunately, not all cameras are at hand at the same time, and they usually cannot be compared.

Fortunately, we had such an opportunity. Moreover, we were lucky that the weather allowed us to recreate the perfect conditions for the comparative tests. It was moonless night, the sky was clear, and it was only necessary to go out of town, away from the artificial lighting.

We had the following cameras available:

1.1 IIT - an image intensifier tube of the third generation. The best of all IIT-type instruments you have come across. It is very difficult to create conditions under which it sees nothing. The resolution of the tube is 68lp/mm. The maximum spectral sensitivity should be around 800 nm. The IIT is combined with a VC249 camera based on a low-noise sensor. The resolution of the camera is much higher than the resolution of the image intensifier, so the camera does not affect the result.

1.2 VS320 - a near-IR camera (SWIR) with sensitivity in the spectral range from 0.9 to 1.8 µm. The resolution is 320x256, the size of the photosensitive element is 25x25 µm.

1.3 VC400 – camera with backside-illuminated scientific CMOS image. Resolution 2048х2048, the size of the photosensitive element is 11 µm. The maximum spectral characteristic is around of 550 nm.

Survey conditions:

1. Date: the night from 8 to 9 January of 2018.

2. Moonless starry night.

3. Limiting magnitude to 19.

4. Illuminance ~0.004 Lux

5. Exposure time of all cameras 40 ms, which corresponds to a frame rate of 25 Hz.


Below we can see the images from the image intensifier tube Gen3, VC320 (SWIR) camera and our newest CMOS camera VC400:





As it is seen, the fields of views are different. It was difficult to get the image lenses with the same f-number that would provide the same field of view.

You may ask why do we have this light source in the hand? It is a LED with a diffuser that we need in order to prove the exposure time is 40 ms. The trace from the LED on the picture corresponds to 40 ms exposure time:














There are no shadows from the objects on the previous images that means it was moonless night. Usually a lot of camera manufacturers do not specify at that lightning condition the image was taken, but they are mostly done at the presence of the Moon that makes the results look complete different in comparison to the moonless night.

The images of the house at the greater distance (IIT, VC400, VC320):

Of the features that can be noticed: the sky in the near infrared range (up to 2 µm) is really very bright.

Also, some might think that the VS320 in the near infrared does not see the stars, but if we zoom in actually they are visible:















Again, the same house closer (IIT, VC400, VS320):

Despite the fact that the VS320 is not a thermal imager (in the classical sense), its sensitivity is enough to notice the IR illumination from the cooling stove in the house.

A small bonus for readers: a test table with different cameras when illuminated by the stars. The L3 camera, manufactured by e2v, is very sensitive camera and considered to be one of the best. The sensor of the camera has a rectangular pixel of a large area (14x28 µm) and is an EMCCD sensor with electronic multiplication, each registered electron in the sensor is multiplied 1000 times:

It may seem that there is nothing special about these images. But let see the images from the low-level cameras (CCD cameras) with the same lighting conditions:


We can see the big difference in signal to noise ratio and significant deteriorating of the image quality.


Conclusion:

1. The VS320 near-IR camera performed quite well at the low light conditions. But usually the price of such cameras based on InGaAs technology is higher in comparison to CMOS sensors.

2. The third-generation image tube showed good results, but the drawback is the low resolution of 68 lp/mm.

3. The VC400 Camera exceeds the other test cameras in the performance. It has high sensitivity at low light, high resolution and it is still CMOS sensor technology. It can be used day and night without deteriorating the performance.


For all additional questions please write us email: info@optolabcam.de or call us: +4917631318323 (Germany). We would be happy to discuss it with you!


Below you can see the pictures taken by VC400 camera with the Newton telescope (D = 200mm F = 1000mm):


The Orion Nebula:


and the Galaxy M81:




All the pictures can be used only with our permission or giving a link to this article.

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