MEASUREMENT & MONITORING OPTICAL DISTANCE SENSORS
MICRO-EPSILON
Advantages of optical sensors in coordinate measuring machines
Coordinate measuring machines are used for high precision quality and parts inspection . Optical distance sensors are increasingly being used for this purpose to replace conventional mechanical gauges . There are numerous reasons for using non-contact sensors : the measurement is reactionless , fast and offers high resolution . Modern optical sensors such as laser triangulation sensors , laser scanners and confocal sensors are particularly suitable for this purpose , says Glenn Wedgbrow , Business Development Manager at Micro-Epsilon UK .
Coordinate measuring machines ( CMMs ) detect the geometrical properties of workpieces in detail . For many years , measuring systems were equipped with tactile sensors , but these are increasingly being replaced by optical sensors . Optical sensors offer numerous advantages over tactile measurement technology . Laser triangulation sensors , laser scanners and confocal chromatic sensors measure the target without making contact . This means that the sensors do not have any influence on the measuring object . The measurements are performed with micrometer accuracy and are normally faster than contact measurement methods .
In practical use , optical sensors are extremely flexible . They measure distance , dimensions , position , angles , shape , roughness and even 3D profiles . Micro- Epsilon offers a broad sensor portfolio that has proven itself in numerous measuring machines . The sensors are used in various systems for both measurement and precise positioning . to integrate . The lightweight , robust laser sensor makes it ideal for measurements with high accelerations . The sensor operates at measuring rates of up to 10 kHz and offers a linearity of ± 1 µ m and a repeatability of 0.1 µ m . The measurements can be started via the encoder pulse of the CMM , thus achieving absolute time-synchronous values . Due to the sensor ’ s intelligent Advanced Surface Compensation feature , stable results are achieved , even on challenging surfaces . With up to 50,000 lx , the sensors are extremely resistant to ambient light and can therefore be used in highly illuminated environments . For signal optimisation , two-stage measurement averaging is available , which enables a smooth signal curve at edges and steps .
Micro-Epsilon offers a broad sensor portfolio that has proven itself in numerous measuring machines .
Roughness measurement and geometrical inspection
In terms of resolution and measuring rate , confocal chromatic sensors are among the most powerful measuring systems in optical metrology . For example , they are used for high-resolution distance measurement on various surfaces and for roughness measurement . The confocal sensor systems from Micro-Epsilon combine stateof-the-art technology and easy integration . The sensors allow a tilt angle of up to ± 30 ° and offer a high numerical aperture . This enables high resolution and small light spots . Curved and structured surfaces can therefore be detected precisely and reliably . In this way , gears or external threads can also be detected . Due to the non-contact measuring principle , the sensor does not affect the target object , which enables wear-free measurements . This is why values can be detected much faster compared to tactile measuring principles . With the confocalDT controllers , measuring rates of up to 70 kHz can be achieved . For measurement in confined spaces , compact sensors , as well as sensors with a 90 ° beam path are available , which can be integrated in the CMM measuring head to save space .
Fine positioning with laser triangulation sensors
For positioning of the measuring head , optoNCDT 1900 laser triangulation sensors measure the distance to the target or baseplate . This type of sensor is particularly suitable for precise distance control and object detection . This allows the CMM ’ s geometry data acquisition systems to be aligned with maximum precision . The laser sensors are integrated into the measuring head system , which is typically attached to the vertical z-axis – the quill . The laser sensor delivers maximum signal stability and due to its compact design , is easy
CMMs detect the geometrical properties of workpieces . Optical sensors offer many advantages over tactile measurement technology , as measurements are reactionless , high resolution and fast .
112 PECM Issue 61