TeleStar Sensor Helps Metrologists "See the Light"

The new TeleStar TTL sensor from OGP is breaking down conventional barriers to successful high resolution surface contour measurement.

Available for use with any new models within the OGP SmartScope Vantage family of multi-sensor measuring machines, the TeleStar TTL (through-the-lens) sensor features an innovative and patented interferometric range sensor design which works by diagnosing the properties of two or more light waves by studying the pattern of the interference created when overlapped.

This design brings many benefits including long working distances and the ability to measure both diffuse and specula surface to the same high accuracy. An additional advantage is that the sensor can measure deeply recessed surfaces through small apertures.

Although the term ‘multi-sensor" is being mentioned increasingly within metrology circles, when applied to SmartScope technology there is a vital difference. Traditional camera-based measuring systems with added laser technology have left many users dissatisfied due to the inevitable compromise to the working distance of the optics, leaving their real potential unfulfilled. However, for the first time in industry, SmartScope Vantage coordinate measuring machines from OGP negate this problem thanks to the innovative and proprietary TeleStar TTL sensor.

Unlike triangulation lasers, where accuracy is a function of front lens diameter and working distance, the incident and reflected light of the TeleStar TTL sensor are coaxial, making it capable of measuring areas on parts where light could be obscured due to the entrance/exit angles of triangulation sensors. Its interferometric range sensor converts light from the reflected beam into positioning data as it is scanned across the contours of a component. Yet such is its capability that it can still measure when its path is blocked by up to 60%.

For this reason, the new TeleStar TTL sensor is well suited to measuring through small holes, tight channels and deep slots, or parts with high, upright walls. In one particular obstruction test, the system managed to collect data successfully from a 0.025mm gap set between two 25mm tall gauge blocks. It is also well suited to measuring the same part either with a highly polished, reflective surface or after coating with a dull, non-reflective surface.

Sure enough, a touch probe with a suitable stylus might be able to reach a deeply recessed feature, but using a probe may be complicated because of the required approach and back-off distance. Respecting safe zones further complicates use. For example, a touch probe system must have enough Z-axis travel to get the stylus from the change rack, raise it above the edge of the part and move it down to the surface being measured.

Another advantage is that the TeleStar TTL sensor’s coaxial through-the-lens design permits video imaging of the component along the same optical path. Since the sensor is coincident with the video optical system it can be deployed within the entire XY range of motion during multi-sensor measurements, allowing users to switch between video and TeleStar measurements almost instantaneously.

Operating with OGP’s MeasureMind 3D multi-sensor metrology software, the TeleStar TTL sensor is a completely integrated function of the zoom lens capability offered by OGP SmartScope Vantage coordinate measuring machines, providing users with a maximum resolution of 0.2 µm and accuracy of 2.0 µm. It brings to market a genuine solution for measuring features that are difficult for other types of laser, optical or touch-probe sensing systems.

We are exhibiting a cross section of its latest non-contact and multi-sensor SmartScope metrology systems at MACH 2010, visitors to Hall 5, Stand 5261 will be treated to the first UK demonstration of OGP’s new TeleStar TTL (through-the-lens) sensor.