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Temperature measurement fully integrated into automated inspection processes

STEMMER IMAGING now provides machine vision users with the capability to include fully calibrated temperature measurements from thermal imaging cameras with traditional machine vision measurements.

Real time non-contact temperature measurement is an important monitoring and control tool in a number of different industries such as automotive, food, electronics, steel, glass, rail and packaging. So far, however, temperature measurements were rarely used for evaluation purposes in vision inspection systems.

Now it is much easier to incorporate such measurements into vision systems that use the Sherlock machine vision platform from Teledyne DALSA. A Sherlock/CVB driver from STEMMER IMAGING provides access to temperature measurement data when using other manufacturers’ thermal imaging cameras.

The big advantage of this method is the fact that temperature measurement has been added to the rich suite of proven vision tools and advanced algorithms provided by Sherlock and Common Vision Blox which can be used to evalute the acquired thermal images. These include search (pattern finding), ID readers, character readers (OCR), measurement and counting tools, contour tools, texture and colour classifiers. In this way, users can create test systems that enable temperature measurements and subsequent image evaluation and processing to be made with low complexity and significantly reduced costs.

Sherlock provides a versatile, scalable machine vision environment for use on PC-based vision systems and the Teledyne DALSA Vision Appliance multi-camera platform range. It fully supports Teledyne DALSA's own comprehensive range of cameras and acquisition cards, but can also be used with a large variety of cameras from different manufacturers through STEMMER IMAGING’s image acquisition engine for Sherlock. This plug-in uses the Common Vision Blox (CVB) Image Manager to acquire images from GigE Vision and GenICam compatible frame grabbers and cameras. This means that data can be captured from any suitable camera and transferred to Sherlock for evaluation with no special interfacing software or hardware required. For GigE Vision and USB3 Vision cameras supplied by STEMMER IMAGING the plug-in is licenced free of charge with CVB CameraSuite.

The combination of Sherlock and the Xenics Serval-640 LWIR GigE camera shows the power of this system providing temperature measurements and further processing of the acquired image data at the same time. When used with this LWIR camera, temperature measurements can be made from -20˚C to +400˚C (tested using a blackbody radiator) with the camera providing an imaging resolution of 640 x 480 pixels. The Serval-640 allows relative and absolute temperature measurements to be made, due to a highly accurate factory calibration.

Teledyne DALSA’s own new series of Calibir uncooled thermal imaging cameras is also particularly exciting for users who are looking for solutions in the area of temperature detection. These cameras’ special highlights are their compact design with dimensions starting from 29mm x 29mm x 29mm, a variety of focal lengths and different interfaces at an attractive price point. The GigE models can easily be integrated into machine vision software products available on the market and can quickly be deployed.

A special feature is the Calibir GXT series, which allows real radiometric temperature measurements without using a mechanical shutter. As a rule, radiometrically calibrated cameras require this mechanical shutter to periodically recalibrate the sensor, since otherwise the displayed temperature values would drift away from the real measured value. However, this calibration process results in a short-term image freeze so that sequences of up to 2 seconds can be lost during recording. In principle, the Calibir GXT can be used without such a shutter and can thus continuously record the measured values without these interruptions. However, Calibir models with a shutter are available for increased accuracy requirements.

These types of thermal imaging sytems are ideally suited for use in the automotive sector to inspect heatable windshields or vehicle seats as well as to monitor heat treatments of vehicle parts. Other typical applications for temperature measurements can be found in food production, solar cell production, printed circuit board inspection, in the hot rolling of steel, in the testing of layer deposition in semiconductors, or in the inspection of shapes in response to temperature changes.

Due to its compatibility with GigE Vision and GenICam, Sherlock allows the integration of suitable thermal imaging cameras in combination with other standard compliant acquisition systems. Depending on the task, applications with conventional monochrome or colour cameras can be realised as well as shape-from-shading systems based on CVS Trevista, 3D applications using the LMI Gocator, hyperspectral systems or Line Scan Bars. Sherlock's versatility for multiple hardware platforms assures both developers and integrators can always utilise the right configuration, without compromising the measurement capabilities.