FAQ No. FAQ03292
Question
What problems occur when measuring hot objects with Z300 Displacement
/ Measuring Sensor?
Answer
There are three problems. Heat rays generated from the object are
confused with the reflected laser beams received by the Sensor, the
ambient temperature around the Sensor rises, and the heat creates a layer
of air that is at a different temperature, causing light to be refracted
and produce errors.
1. Generation of Heat Rays
Hot objects emit heat rays. These heat rays can cause measurement errors.
The Z300 Sensors use visible red light lasers. There is a filter on the
receiver lens which passes through wavelengths of 600 to 720 nm. The CCD
receiver element will not accept wavelengths above 1 μm.
Heat rays emitted from the hot object are similar in wavelength to the
laser beam, so the receiver element may detect the heat rays. Conduct
tests with the actual system to determine how much it is affected by heat
rays.
ZX-L-N Smart Sensor and
Z500 Profile Measuring System face the same problem.
Laser wavelengths of the main Displacement Sensors are as follows:
Z300-S2: 650 nm, Z300-S5 and Z300-S10: 670 nm, Z300-S60: 658 nm, Z500-SW2:
650 nm, Z500-SW6 and Z500-17: 658 nm, all models of ZX-L: 650 nm.
2. Rise of Ambient Temperature around the Sensor and the Temperature of
Sensor Itself
There may be a heat-related problem. Check the ambient temperature
specification in the catalog and install a cooling device (such as a fan)
to make sure that the temperature stays within the specified range.
Additional Information: Make sure that cooling is applied regularly to
maintain the ambient temperature around the Sensor at a certain level. If
the cooling is turned ON and OFF, the Sensor casing and mounting board may
expand and contract due to the temperature change, causing measurement
errors.
3. Measurement Error Due to Refraction of Light
A layer of hot air forms around the hot object, but the air surrounding
the Sensor is at room temperature. This forms a temperature gradient
between the two locations, which is equivalent to a gradient in air
density. Light is refracted where the densities differ. The Z300 uses
triangulation, so refraction of light will lead to a measurement error.
If you want to measure a hot object, check first whether these Sensors can
be used to make measurements to the required accuracy.
Other Displacement Sensor FAQs
 What is the width resolution of the Z500?
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