Lighting and optics selection study

Solution concept

The pixel density required for the given part and smallest defect is calculated; the camera is moved along an optical rail to change the working distance. The real scale and field of view are measured with a calibration target; the set-up is confirmed when the part is in frame and the pixels per defect are sufficient.

optical railcalibration targetpixels per mmfield of view

Information delivered

The selected focal length, working distance, field of view and pixels-per-mm value are written to the design report; the calibration file is handed over to the application project.

Scenes are illustrative simulations; they are not customer references or performance guarantees.

All applications in this industry →Request Feasibility

Need

As the field of view grows, fewer pixels fall on each defect; when it is narrowed, the part leaves the frame. Focal length, working distance and depth of field are coupled; changing one upsets the others.

Solution approach

The required pixels per mm and field of view are computed from the part size and the smallest feature. The camera is moved along the rail to scan the working distance; at every position the checkerboard calibration target is imaged and scale and distortion are measured from the square size. The position is recorded when the part is in frame and the scale is above the target.

Process steps

01
Calculation
Required field of view and pixels per mm are computed from part size and smallest defect.
02
Distance
The camera moves along the rail; the working distance changes.
03
Calibration
The checkerboard target is imaged; the scale is measured from the square size.
04
Verification
It is checked that the part is in frame and that the pixels per defect are sufficient.
05
Decide
Field of view and scale are compared with the target values.