Technologies

Diascopic projection

The contour of the part under inspection is viewed using sharp-edged profile projection where the image obtained is highly contrasted. Parallel lighting combined with telecentric optics produces levels of precision on the order of 1/2500th of the field of measurement.
Example : diameter measurement of a 20 mm sphere with a 10 mm margin of error.

Episcopic projection

The object is front-lit. The quality of the image is influenced by many factors: surface quality of the object, shape, colour... Solid-state uniform lighting combined with interferential filtering produces levels of precision which are typically on the order of 1/1000th of the field of measurement.
Example : diameter measurement of a 20 mm sphere with a 0.0025 mm margin of error.

Telecentric optics

Telecentric systems provide constant perspective across the field as well as large depth of field for consistent field magnification-the dimensions of the object under inspection do not vary as a function of distance from the camera.
Example : measurement of an object of dimension a=10 mm at a distance of 100 mm from lens
- with a conventional lens. A dd=0.1 mm change in distance to camera will produce a d/d=1/1000th error. The error in measurement of object "a" will thus produce the same d/d ratio, i.e. a 0,01 mm error.
- with a telecentric lens located at nominal distance from the object the magnification error is compensated.

Parallel lighting

Parallel lighting obtains strongly contrasted outlines.
With conventional lighting, the transition from black to white produces a grey gradation several pixels wide. With parallel lighting, the transition takes less than 1 pixel- which allows for repeatability between successive shots.

Triangulation

Triangulation is a technique for measuring the distance to an object through observation of the object in combination with an angle of parallax.
Generally, for relatively dull objects, the angle of incidence of lighting is perpendicular to the part under inspection, and the receiver is tilted between 15 and 45°.
The discrepancy depends largely on the type of surface to be controlled. Depending on the material involved, with this technique it is possible to reach a level of discrepancy of 500 to 2000 points with respect to the overall measurement.

[LCI][Home][News][Applications][Products][Technologies][Customers][Contact]

© le contrôle industriel last revision: 11/2/2005