FAQ No. FAQ01400
Question
What is the principle of diffuse reflection measurements?
Answer
When the distance of the sensing object changes, the position where the
light is received on the receiver element changes. This change is
converted into a displacement reading.
The laser light is emitted from the emitter lens towards the sensing
object. The light that is reflected off the object is collected by the
receiver and an image is formed on the PSD. If the distance of the sensing
object differs, the image formed on the PSD varies. The two PSD outputs
will change.
The ratio of these two outputs is found and then converted to a distance.
Compared to a CCD, a PSD is smaller, faster and can be produced at lower
cost.
Smart Sensors Using Diffuse Reflection -
ZX-LD40(L), ZX-LD100(L), ZX-LD300(L)
The difference between the diffuse reflection method and the regular
reflection method is described below.
The diffuse reflection method collects the diffuse light reflected from
the sensing object.
The diffuse reflection method gives stable measurements. It can be used
even when the reflection angle variation is large. If the surface is
shiny, the accuracy becomes low and it may not be able to make
measurements.
The regular reflection method detects the object using regular reflection.
Accurate measurements can be made for shiny surfaces but it doesn't have a
large tolerance for angle variance.
Other Displacement Sensor FAQs
 Are there any precautions for using the E4PA to detect the liquid level in a tank?
Does the temperature of the sensing object affect the detection ability of the E4PA?
What is resolution?
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