Confocal measurement sensors

The use of non contact measurement systems has seen a significant rise in industry over the last couple of decades. Systems use to rely on the mechanical deviation of a cam or deflection of a thin plate that had to be in direct contact with the product being manufactured. Now precise measurement of a multitude of applications can be done suing the latest sensing technologies.

The move to these non contact forms of measurement has perhaps been driven by the need for more accurate measurements, and the need to take measurements on increasingly difficult surfaces. For example, some surfaces such as glass or electronic products may be damaged by coming into contact with a mechanical measuring probe or other device.

There are a range of different sensing technologies now available that can cope with these further demanding requirements. Some of these are listed below:

• Eddy current sensors
• Capacitive sensors
• Confocal sensors
• Laser triangulation sensors
• Inductive sensors

Confocal measuring technology

Confocal measurement works by using a multiple lens optical system which focuses polychromatic white light onto a target surface. The white light disperses when it hits the target, and the wavelength of the light that is focussed onto the target surface after the chromatic deviation is used to determine the measurement. This principal means that distance and displacement can be measured extremely accurately.