Laser profilometry

The laser profilometry is a non-contact measuring method for surface profiles with a precision in the .mu.m range scan.

Measurement

Laser profilometer - basic representation of a laser triangulation sensor. The laser beam is projected onto the measurement object. The lens images the light spot onto the CCD or PSD sensor. A displacement of the object also leads to a displacement of the image on the sensor.

The measurement method is based on the principle of triangulation . A fanned out laser projects a laser line onto the surface to be measured. The laser line is observed by a camera sensor built into the sensor . The distance of the measuring object from the laser line is directly proportional to the position of the projection on the image plane of the camera.

There are also other methods for optical sensors that determine defocusing based on roughness or structures. The height difference in the micrometer range can be determined from the difference signal . The focusing unit is reset to the focusing distance by means of a micro-adjustment unit (micro-coil or piezo element ).

Laser profilometry cannot be used if the material to be examined is transparent to the laser light used .

Applications

The measurement of surface profiles is used in material analysis, for example, the measurement of friction surfaces, as well as in manufacturing technology for quality assurance. In medicine, among other things, it is used in dermatology to diagnose skin diseases.

Individual evidence

1. ↑ Marcus Freitag: Non-invasive laser profilometry based on the principle of dynamic focusing: examinations in cutaneous malignant melanoma and selected differential diagnoses. In: Dissertation. High Medical Faculty of the Ruhr University Bochum, accessed in 2002 .