FAQ00471 of Displacement Sensors / Measurement Sensors FAQ

Transparent objects, which allow light to pass through, cannot be measured because Reflective Smart Sensors use a PSD and Through-beam Smart Sensors use a PD. If the transparency and required accuracy are low, it might be possible to use the ZX-L for some applications. We recommend that you conduct tests with the actual object first. If the transparency and required accuracy are high, the following Sensors can be used to measure transparent objects.

CCDs enable detecting transparent objects.

Sensing with a PSD (Not suitable for transparent objects.)

A Regular Reflective Sensor that uses a PSD cannot distinguish the light reflected from the surface because it is affected by the light reflected from the other side of the object and/or the background. For this reason, displacement of the surface cannot be accurately measured. A Diffuse Reflective Sensors cannot make measurements because the diffused light is too small.

Sensing with a CCD

A Regular Reflective Sensor with a CCD can extract the light reflected from the surface because it can distinguish between the light reflected from the surface and the light reflected from the other side. For this reason, displacement of the surface can be accurately measured without being affected by the light reflected from the other side and/or the background.

Through-beam Sensors

Z4LC-series Separate-Amplifier Parallel Beam Line Sensors

The above Sensors can detect the edge of transparent objects by using a CCD in transparent object detection mode.

3Z4L-series Laser Micrometers

The above Micrometers can be used to detect the outer diameter or edge position of transparent objects using a laser scan method as the measurement principle.