SCHOTT solutions no. 1/2016 > Optical Metrology

Zeiss Optical Metrology
ZEISS O-SELECT features two light components from SCHOTT: incident light with 160 LEDs in eight segments and transmitted light that shines from below. Photo: Zeiss

Automatically in the best light

Automated optical measurement systems are gradually replacing manual instruments in production. Here, the optimal illumination also determines the test quality. The digital measuring projector ZEISS O-SELECT with an LED ring light from SCHOTT and transmitted light illustrates this.

Thilo Horvatitsch

Asmall gear only a few millimeters in size is lying on the glass measuring field. As part of a medical gear, it is designed to enable enormous operating speeds without experiencing a breakdown: up to 450 revolutions per second. This means its tooth widths and its diameter must be manufactured with precise accuracy to hundredths of a millimeter. Manual instruments and tedious measurements by hand no longer suffice for such demanding quality assurance and precise examination of such tiny dimensions and tolerances. Therefore, the manufacturer uses a measuring instrument that cannot only carry out sample measurements in a reproducible manner, but also delivers and documents results quickly and at your fingertips: the optical measuring system ZEISS O-SELECT.
Optical Metrology
Measurement at the press of a button: ZEISS O-SELECT automatically adjusts the correct distance between the camera and the workpiece, but also the right light, and displays the visual results on a monitor. Photo: Zeiss
It is very easy to operate. Once the part to be measured is ready, the operator needs only to press the only button on the device. The telecentric optical system automatically adjusts the correct camera distance and the right lighting. The visual result appears on the monitor – with all of the dimensions of the detected geometric elements. The inspection parameters can now be selected. At the same time, the device suggests a measurement routine for future inspections. The respective correct illumination is crucial to performing optical measurements. It influences important parameters such as the depth of focus, whereby imprecise settings would lead to measurement errors. For this reason, ZEISS O-SELECT is equipped with high-power, flexible light components from SCHOTT: first, a beam that shines from below for measuring contours and broken parts; second, an incident light, which, for example, illuminates depressions, edges or slanted surfaces from above. The latter consists of a double ring light that features 160 LEDs in eight segments that can be controlled individually. ”By using extensive optical simulations and optimizing each LED, we were able to achieve extremely homogeneous illumination – for maximum contrast and the best possible test requirements,” explains Dr. Bernd Wölfing from SCHOTT. The meter calculates the appropriate illumination intensity for the light components automatically, depending on the properties of the workpiece and the position of the inspection traits. Thus, gaps, radii or angles in punching and bending parts, injection molded or laser cut workpieces, such as those used in the automotive industry and medical technology, can be recorded without error in a very short period of time. ”Realizing the complex interplay of optics and illumination meteorologically and automating it makes the measurement traceable, reproducible and therefore reliable,” says Andrzej Grzesiak, Director of Metrology Systems at ZEISS. <
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