There are 2 modes that the sensor can be measure; Distance and Product Height. They are quite different, and set in the Global Options. Along with these modes, there are variables that must be set for the Min and Max to measure when in each mode:
1) Distance: When Distance mode is selected, then the output on the screen displays "Distance" and the value is the measurement from the sensor window to the top of the product (where the laser is hitting). This has a physical operational range of 65 mm to 155 mm. You can restrict the range by using the Min and Max setting in the product setup. For example, if you would like to restrict the measurements between 80 and 100 mm, then you would enter a Min value of 80 and a max value of 100. Anything outside that range will be ignored in the color measurement.
2) Height: When Height mode is selected, the output on the screen will display "Height" and the value is the measurement from the user entered Belt or Background distance and the top of the product (where the laser is hitting). This has a physical operating range of 0- 90 mm. You MUST enter a Belt or Background distance that represents the distance to the bottom of the product or the bottom of the sample tray. For example, if the product you wish to measure has a 10 mm thickness, then the sensor head should be adjusted until the product surface is 90 mm from the sensor window, and the background/Belt should be set to 100 mm. You may then select a minimum height, and a maximum height to restrict the measurement range. Please see the user manual for more information.
There is also a diagnostic feature called "Distance Sensor". This always gives the distance measurement (as above) and is used when initially setting up the sensor head to 90 mm above the product. Please note that not all surfaces can be accurately measured and there is the limit of a minimum of 65 mm and a maximum of 155 mm. If the product is closer or further from the sensor window than those values, the Distance Sensor will be incorrect.
Please also see the instructions for initially setting up a product in the support site: https://support.hunterlab.com/hc/en-us/articles/212149166-Initial-Setup-of-D25NC