Use Night Vision Goggle to Enhance Vision tweet

Submitted by laurenmeloche on Tue, 04/19/2022 - 15:12

Humans do not have great night vision, as rods are the only cell that can work in low light. Cones only work when there is a great amount of light. If it is darker than a half moon at night, then rods will be used. Rods cannot detect different wavelengths of lights and make up most of the retina, but they do not make up the detailed images.

Because of this, humans often use night vision goggles (NVG) in order to see better at night. There are two different primary types of night vision goggles that utilize different technology. There are both image enhancement and thermal imaging. Image enhancement can be utilized by collecting all available light, and then enhancing this image so it can be seen better. It uses infrared light by capturing it as it is a longer wavelength than red light. Thermal imaging is used mostly on people, as the goggle picks up on the heat given off from people.

To dive deeper into image enhancement, NVG’s use multiple lenses to capture and amplify incoming light. The first lens is an objective lense, which takes dim light reflected from the object, and passes the photons into an image-intensifier tube. These are then converted into electrons, which flow into the microchannel plate (MCP). This multiplies the number of electrons present, and they hit a phosphor-coated screen as they leave. 

The screen lights up when hit, which creates the glowing green image that is often much brighter than the initial dim light.

Interestingly enough, frogs and toads can see in almost total darkness. Their rods have two different types of sensitivities. It is suspected this is why frogs can also see colors in low lighting as well. 

 

 

https://wonderopolis.org/wonder/how-do-night-vision-goggles-work#:~:text=Night%20vision%20goggles%20use%20thermal,see%20people%20in%20the%20dark

https://visionsource.com/blog/how-does-our-night-vision-compare/

https://www.lunduniversity.lu.se/article/frogs-have-unique-ability-see-colour-dark

https://www.huffpost.com/entry/night-vision-gear_n_59f38cf2e4b03cd20b8196bf

 

Comments

Submitted by eeggers on Tue, 04/19/2022 - 15:41

Permalink

Interesting- for the rods it is sort of more complicated for humans.  Technically, human retinas are rod -dominant.  But the fovea is cone dominant, which is what we use for all of our detailed vision.  Is there a better way to describe that?

Also, the night vision goggles amplify any visible light, but they also use near infrared (not heat imaging, just light that is slightly longer wavelength than red light).