Things about image sensor
Image size, sensor size, screen size (image size, image format)
The size of the light receiving surface of the image sensor is called “image size”, “sensor size”, or “screen size”.
the corresponding lens is required to have a more “image circle” image size of the camera. it should be noted that depending on the camera, objects or the image sensor is different from the typical value for the same type of display, of the image sensor “enable Only the “effective pixel (video output pixel)” range is output from the camera instead of the “pixel”, and the image size of the image sensor and the actual image size of the camera (effective image size) may differ, so optical accuracy is particularly required. Care must be taken in various applications.
Image circle, effective image circle
Normally, the camera lens is focused statue circular range, the range of the diameter of the optical performance image circle that can be ensured by the “image circle”, or called “effective image circle”
corresponding to the lens The camera has an “image size” that is smaller than the image circle, but if the image size is large, there will be optical problems such as “kicking” and “blurring” in which the light does not reach the corners of the screen sufficiently and it becomes dark. It will occur.
Pixel pitch, pixel size
The pixel spacing of the image sensor is called “pixel pitch” or “pixel size”.
The size of the “pixel pitch” affects the optical performance such as the “resolution”, which is one of the optical performances of the lens, and the “allowable circle of confusion diameter” used to obtain the “depth of field”.
Image height
The size of the image from the optical axis is referred to as “image height” and is called “elephant” or “elephant”.
For example, when using a diagonal 8 mm camera, the “image height” at the outermost corner of the screen is 4 mm.
There are “center” and “periphery” as terms that indicate the image height when evaluating lens performance. The “center” is originally the position of the “optical axis”, but in actual test chart measurements, it usually means “near the optical axis”. In addition, “periphery” refers to the image height of “a position away from the optical axis”, but it seems that 70% image height (70% position of the image height of the screen corner) is common for photographic lenses, CCTV, and surveillance applications. is. On the other hand, for high-definition machine vision applications, it is ideal to process the entire screen in the same way, and evaluation at 100% image height (screen corner) is recommended.
Resolution, resolving power
The closest limit at which two points that are slightly separated appear to be separated is called “resolution”.
In photography lenses, this “resolution” is often expressed as “resolution”, which means how many sets of black-and-white stripe patterns are included per 1 mm, and the units are “book / mm” and “lp / mm” (line pair par). (Read as millimeters), “cycles / mm” is generally used as a value called “spatial frequency”. In addition, the resolution of shooting lenses is traditionally in order from coarse to fine … 10, 12.5, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 160, 200, 250 … (book) It is often displayed as “standard number R10 sequence 9”, which is a step of / mm).
Please note that the “resolution” is different from the “resolution” used in image sensors and monitors.
Source: https://www.dzoptics.com/en/