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Anonymous users2024-01-23It is recommended that you buy a smart electronic cat's eye Automatic detection, automatic photography, automatic video recording, and SOS SOS for help are very practical! Now the market is very general.
Concave lenses. The concave lens is a virtual image with upright and shrinking regardless of the distance. It is mounted on the outside of the door. >>>More
There are a total of 4 lenses in the cat's eye; 1 flat lens in the front and back, 2 concave and convex in the middle, facing each other in the front! As for the principle, I don't know much!
If you enter, you will enter. It can't be broken. Besides, even if it's broken, it's only a matter of ten or twenty yuan to change it. Don't worry.
Generally, the cat's eye of the security door is in the middle of the door leaf.
Optical principle of portal mirror imaging.
The door mirror is composed of two lenses When we look out from the inside of the door, the objective lens L1 is a concave lens, and the eyepiece L2 is a convex lens (see Figure 1 for the optical path) The focal length of the objective lens L1 is extremely short, and it AB the outdoor person or object AB into a very small upright virtual image A B, this image just falls in the first focus of the eyepiece L2, L2 plays the role of a magnifying glass, and finally obtains a more magnified upright virtual image A B, which is just around the bright distance of the human eye, and can see clearly for the situation outside the door >>>More