I. Calculation Methods for Industrial Lenses in Machine Vision
II. Camera and Lens Selection Tips
1. Main parameters of the camera:
Photosensitive area SS (Sensor Size)
2. Main parameters of the lens:
Focal length (FL)
Minimum Focal Distance (Dmin)
3. Other parameters:
Field of View (FOV)
Pixel
FOVmin = SS(Dmin/FL)
For example: SS=6.4mm, Dmin=8in, FL=12mmpixel=640*480
Therefore: FOVmin = 6.4 (8/12) = 4.23 mm 4.23/640 = 0.007 mm
If the required accuracy is 0.01mm, then 1 pixel = 0.007mm < 0.01mm.
Conclusion: The desired accuracy can be achieved.
III. Industrial camera sensor dimensions: (unit: mm)
1/4″: (3.2mm&TImes;2.4mm); 1/3″: (4.8mm&TImes;3.6mm); 1/2″: (6.4mm&TImes;4.8mm);
2/3″: (8.8mm&TImes;6.6mm); 1″: (12.8mm×9.6mm);
IV. Dimensions of CCD Camera Elements
V. Linear array sensor dimensions (unit: mm)
VI. Formula:
Resolution (μm) = 0.61 (fixed value) x 0.55 (design wavelength) ÷ NA
Effective FNo = Magnification / 2NA
Depth of field (mm) = 2 (acceptable blur circle diameter x effective FNo ÷ magnification 2)
Luminous flux diameter (φ) = 2NA x object height + field of view (angle)
VII. Methods for determining monitor magnification and overall magnification:
Display magnification = Display size in inches x 25.4 (1 inch) ÷ CCD camera diagonal size
Overall magnification = Display magnification x Optical magnification
Example: The combination of a 2x optical magnification lens and a 1/2'' CCD camera results in a combined image magnification on a 14'' monitor.
Overall multiplier = 44.45 x 2 = 88.9
8. Optical magnification
Optical magnification
Image size relative to the magnification of the object
β=y'/y
=b/a
=NA/NA'
=CCD camera element size / actual field of view size
Electronic amplification
Electronic magnification is the magnification by which the image captured by a camera and projected onto a CCD is displayed on a monitor.
Display magnification
Display magnification is the magnification by which the image of the photographed object is displayed on the display screen after passing through the lens.
Display magnification = (optical magnification) × (electronic magnification)
Example: Optical magnification = 0.2X, CCD size 1/2 (diagonal length 8mm), monitor 14".
Electronic amplification = 14 × 25.4 / 8 = 44.45 (times)
Monitor magnification = 0.2 × 44.45 = 8.89 (times) (1 inch = 25.4 mm)
Field of view
Field of view is the size of the area where an object can be seen when the lens is connected to a CCD camera.
The field of view size is: (CCD format size) / (optical magnification).
Example: Optical magnification = 0.2X, CCD 1/2″ (4.8mm long, 6.4mm wide)
Field of view size: Length = 4.8 / 0.2 = 24 (mm)
Width = 6.4 / 0.2 = 32 (mm)
