Carl Mahr Holding Gmbh

Peter Lehmann

Norbert Steffens

Wolfgang Osten

Aiko Ruprecht

Jürgen Mohr

Peter Lücke

Carlos Javier Moran-Iglesias

Sven Schönfelder

The apparatus and method according to the invention includes an objective () which is capable of operating basically in two different measuring modes. In a first interference mode, a measuring object () is interference&#x2014;optically measured. In a second imaging operating mode on a detector array () designed like a camera, an optical image is generated, which is supplied to an image processing routine. The switching over between the two operating modes occurs by switching the illumination devices which are associated with different locations of the beam path of the apparatus&#x2014;when viewed from the camera, one in front of a beam divider and the other behind the beam divider, which couples a reference light path to the beam path.

Apparatus and method for a combined interferometric and image based geometric determination, particularly in the microsystem technology

A method for detecting shapes based on interferometric observation of an object surface subjected to narrow-band lighting. Movement of the interferometer () relative to the object surface () generates a measuring signal on a photo receiver, e.g., camera circuit (), from which two extremely closely positioned signal frequencies (f) and (f+&#x394;f) are extracted. The phase difference between the two signal components is used for determining the distance and/or the change in distance. The method has a large unambiguousness range, making it possible to have a large depth measurement range, and can be used for workpieces having offset areas on the surface, wherein the measurement is not disturbed along the edges and the offset areas. The method also allows examining strongly inclined surfaces having a steep inclination such that that traditional methods based on evaluating interference lines cannot be used because of a high density of the interference lines.

Shape measuring method

Shape measurement method

The apparatus according to the invention comprises an object lens which can operate in at least two different measuring modes. In a first, interference mode a workpiece is measured by means of interference optometry. In a second, imaging measuring mode an optical image is produced, for example, on a camera-like detector array and may be applied to an image processing routine. Switching between the two measuring modes is performed by the type of illumination of the object lens and an element which is disposed preferably in the reference beam path of an interferometer and which activates or deactivates the reference beam path dependent on the spectral composition of the utilized light. In this manner a simple and rapid changeover between the two measuring modes is provided, without the need for replacing or even for moving the object lens. Apart from the rapidity of changeover, a good correlation is achieved between the measuring data which are yielded by the interferometry and by the image processing and which are obtained in one and the same reference coordinate system.

Device and method for a combined interferometry and image-based determination of geometry, especially for use in micro system engineering

A measuring head () according to the invention comprises the combination of a zone lens (), which is preferably a diffractive lens, with a hemispherical lens () or a GRIN lens (). This represents a concept capable of miniaturization, resulting in very slender measuring heads () having a high numeric aperture and, accordingly, leads to the best resolution capacity. Such measuring heads are insensitive to angular errors as concerns the orientation of the measuring head to the surface to be measured or to an oblique positioning of the surface relative to the optical axis of the measuring head.

Optical measuring head

A measuring device () for measuring the shape, contour and/or roughness of a workpiece is based on a contact-less optical probe having a large numeric aperture. The probe has at least two different focal points with which at least two photo receptors are associated. The latter generate a differential signal for controlling a positioning device () for tracking the optical probe in such a manner that the workpiece surface is maintained within the measuring range of the probe. The differential signal is proven to result in a rapid and accurate tracking of the position of the sensor arrangement ().

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Gottingen, Germany

Peter Lehmann