| | | sensors range limits. OK is lit, when the object is in the sensors range. Using moving orstriped objects When you measure moving or striped targets, mount the sensor across to the stripes and to the direction of movement. This improves measurement results on edges (see fig. 2). Synchronisation of2 sensors Two sensors can be synchronised, to remove crosstalk from one sensor to the other. They can be synchronised alternating, so that they will not disturb each other measuring close to each other or measuring on partially transparent objects. This master/slave principle is used for thickness measurement systems. Synchronisation depends on type and is available on request. Thickness measurement system A thickness measurement system is made with 2 sensors, master and slave, directed to the upper and to the lower side of the object. Each sensor has a electronic system. Thickness is calculated by addition of the 2 sensor signals in the master unit. The light impulses are synchronised. Both systems work independent. This allows measurement on thin and partially transparent objects. The output of the thickness | | measurement system is 0 ... 10 V. The range of thickness measurement corresponds to the range of the sensor. In the sensors range, thickness is not depending on the objects position. The sensors range should be chosenbiggerthan themaximum expected thickness and movement of the object. Measurement error Measurement can be made on plastic, metal, ceramics, rubber, paper, and so on. On highly shiny and corrugated surfaces a test should be made. On mirroring surfaces and glass, measurement can be made with the M74L, specialized on reflective surfaces. On transparent surfaces or liquids, the light may penetrate into the material, causing an error in displacement measurement. The measurement result should be corrected for the factor of intrusion depth into the material. Scratches in the measurement area Scratches in the across to measurement direction could cause strong reflections having their maximum at the side of the measurement spot. This may cause an error in distance detection. The effect can be used to detect scratches in the surface with a good sensitivity. On moving objects, the average value will remain constant when moving over the scratch. Stray light from the side Mirroring objects near by, where stray light from the sensor is present, may cause stray light reflections into the sensor. This could cause measurement error. Objects with diffuse reflection do not cause this error. When the mirroring object is outside of the measurement spot, the error could be worst case 2%. The error is less with Laser sensors, because the measuremet spot is smaller. Transits between bright and dark surface Measuring on a surface, where the surface goes from diffuse reflection | | to mirroring surface, thus making a big change in reflectivity, an error may occur in the transit range: the maximum intensity is not in the center of the measurement spot. When the borderline of surface reflectivity is in the direction of measurement, the error may be small, in the direction across, the error will be bigger. Change in surface reflectivity Optical sensors use automatic light intensity control for the use on objects with different surface reflectivity. When the surface changes during measurement, the light intensity is controlled accordingly. Angular dependency When the sensor is not aligned 90° in angle to the surface, a small measuring error may result. An inclination of 30° in the axis A and 15° in the axis B do not make a remarkable difference in the measurement result (fig. 4). On mat surface with highly diffuse | | |