In a machine vision system, the lens is equivalent to a human eye, and its main function is to focus the optical image of the target on the photosensitive surface array of the image sensor (camera). All image information processed by the vision system is obtained through the lens, and the quality of the lens directly affects the overall performance of the vision system. The following is a detailed explanation of the technical terms related to machine vision industrial lenses.
Can be divided into pincushion distortion and barrel distortion, as shown below:
The calculated value of the actual side length of the warped shape and the percentage of the ideal shape.
Third, optical magnification
Calculation method:
Example: VS-MS1+10x lens 1/2†CCD camera, imaging on a 14†monitor
The 0.1mm object is imaged at 44.45mm on the monitor. ※Depending on the scan status of the TV monitor, there are some changes in the above simple calculation.
Fifth, the resolution It shows that the interval of 2 points can be seen 0.61x using wavelength (λ) / NA = resolution (μ)
The above calculation method can theoretically calculate the resolution, but does not include distortion.
※Use wavelength is 550nm
The number of black and white lines can be seen in the middle of 1mm. Unit (lp)/mm.
7. MTF (ModulaTIon Transfer FuncTIon)The number of spatial cycles and contrast used to reproduce the change in the shading of the surface of the object during imaging.
Eight, Working Distance (Working Distance)The distance from the lens barrel to the object
N/I (Object to Imager)The distance between objects is the length from object to image.
Ten, imaging circleThe imaging size φ is to be input to the camera sensor size.
XI, camera Mount C-mount: 1 "diameter x 32 TPI: FB: 17.526mm
CS-mount: 1 "diameter x 32 TPI: FB: 12.526mm
F-mount: FB: 46.5mm
M72-Mount: FB manufacturers are different
Field of view refers to the range of the object side seen after using the camera. The longitudinal length (V) / optical magnification (M) of the camera effective area = field of view (V)
Horizontal length (H) / optical magnification (M) of the effective area of ​​the camera = field of view (H)
* The field of view on the technical data refers to the value calculated from the general values ​​of the light source and the effective area.
The longitudinal length of the effective area of ​​the camera (V) or (H) = the size of one pixel of the camera &TImes; the effective number of pixels (V) or (H)
To calculate.
Depth of field refers to the distance of an object after imaging. Also, the range on the camera side is called the depth of focus. The value of the specific depth of field is slightly different.
Fourteen, focal length (f)
f (Focal Length) The distance from the rear principal point (H2) of the optical system to the focal plane.
Fifteen, FNO
When the lens is from infinity, the value represented by the brightness is smaller and brighter. FNO = focal length / incident aperture or effective aperture = f / D
Sixteen, effective F
The brightness of the lens at a limited distance.
Effectiveness F = (1 + optical magnification) x F #
Effective F = optical magnification / 2NA
17. NA (Numerical Aperture)
NA on the object side = sin uxn
Image side NA '= sin u'x n'
As shown in the figure below, the angle u, the refractive index of the object side, and the refractive index of the imaging side 'n'
NA = NA' x magnification
Eighteen, the edge brightness contrast refers to the percentage of the central illuminance and the surrounding illuminance.
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