EP1287314A1 - Probe with a diffraction grating for +1, 0 and -1 orders - Google Patents

Probe with a diffraction grating for +1, 0 and -1 orders

Info

Publication number
EP1287314A1
EP1287314A1 EP01943100A EP01943100A EP1287314A1 EP 1287314 A1 EP1287314 A1 EP 1287314A1 EP 01943100 A EP01943100 A EP 01943100A EP 01943100 A EP01943100 A EP 01943100A EP 1287314 A1 EP1287314 A1 EP 1287314A1
Authority
EP
European Patent Office
Prior art keywords
diffraction grating
interference
measuring device
light
sensor arrangement
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01943100A
Other languages
German (de)
French (fr)
Inventor
Markus Rudolph
Bernd Gusek
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mahr GmbH
Original Assignee
Mahr GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mahr GmbH filed Critical Mahr GmbH
Publication of EP1287314A1 publication Critical patent/EP1287314A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
    • G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses
    • G01D5/38—Forming the light into pulses by diffraction gratings

Definitions

  • the invention relates to a measuring device which is provided in particular for measuring the surface roughness and / or the surface contour of a workpiece.
  • the measurement of workpieces and the determination of special surface properties such as roughness, form stability (contour) and similar measuring tasks are often solved by mechanically probing the surface or surface areas to be measured.
  • Various probes such as spheres, measuring tips, diamond tips or the like are used for this - depending on the measuring task.
  • currency While the mechanical measurement is usually carried out by touching the workpiece surface point by point, it is customary to determine the surface roughness or the surface contour or shape elements of a workpiece by dragging a probe tip, e.g. a diamond tip or a steel tip, over a specified distance at a specified speed and that to record or evaluate deflections of the probe tip that occur essentially at right angles to the workpiece surface.
  • the prerequisite is always the detection of the movement or deflection of the probe element.
  • This requires high-resolution and fast-working linear measuring systems (so-called displacement transducers) or related measuring systems. If the roughness measurement is to be combined with a contour measurement or if only one contour measurement is to be carried out, the probe element generally runs through relatively large strokes during the measurement process. As far as possible, these should lie within the measuring range of the corresponding measuring system.
  • inductive measuring systems are known for measuring linear displacements. As a rule, these emit a signal proportional to the deflection and must therefore be regarded as analog measuring systems.
  • incremental encoders are known, which can also be based on optical principles.
  • DE 19712622 AI an evaluation device for an optically scanned scale division is known.
  • the optical measuring system generates two signals S1, S2, which are fed to the evaluation unit as scanning signals.
  • the scanning signals are 90 ° out of phase and periodic.
  • the signals are routed via an analog / digital converter.
  • the number of maxima passed indicates a number of steps and the precise signal value indicates the path traveled beyond the number of steps.
  • the aforementioned disclosure document deals with not with the type of signal acquisition. Rather, both optical and magnetic scales and thus sensors are taken into account.
  • a photoelectric position measuring device which includes a light source, a stationary diffraction grating, which serves as a beam splitter, and a moving diffraction grating.
  • the first diffraction grating emits diffracted light rays + 1st order and - 1st order. These light rays hit the moving diffraction grating, which reflects the partial rays + 1st order and - 1st order back. They run through the beam splitter again and are brought to interference.
  • the moving diffraction grating which serves as a scale, is thus struck by light that has been broken down and fanned out into several partial beams. Only part of the fanned out light is gathered together by the diffraction grating, which serves as a beam splitter, and brought to interference.
  • a different measuring principle for position measurement is known from EP 0586454 B1.
  • a diffraction grating is illuminated with a parallel light beam capable of interference.
  • the backscattered light beams - 1st order and + 1st order are alternately brought into interference with each other via a beam splitter and the interference images are evaluated by their own detectors.
  • the position of the scale is determined exclusively using the diffracted beams + 1st order and - 1st order. These only carry part of the light energy used. Based on this, it is an object of the invention to provide an optical position sensor which enables good light utilization.
  • the measuring device has a diffraction grating which is hit by a light beam capable of interference.
  • the diffraction grating generates an undiffracted light beam as well as several diffracted light beams, of which the diffracted light beam + 1st order and the diffracted light beam - 1st order together with the undiffracted light beam (0th order) that has passed through the diffraction grating are used to generate an interference image become.
  • the beam maxima zero maximum, plus first maximum and minus first maximum partially overlap, so that an overall bright interference pattern can be generated even with the lowest light source power.
  • very low-power laser diodes can be used to generate the light beam capable of interference.
  • the measuring device allows a high resolution. This can be influenced by changing the grating constant of the diffraction grating and the distance between the light source and the diffraction grating, if with a non-parallel interference-capable light beam is worked.
  • the light bundle emitted by the light source is preferably focused via a corresponding optical device (optics) and the diffraction grating is arranged in the vicinity of the focus point (focal point) or precisely on this.
  • the diffraction grating is preferably aligned transversely to the light beam. However, the diffraction grating does not necessarily have to be arranged precisely at right angles to the light beam. Smaller deviations from the right angle do not interfere or hardly.
  • a rotation or swiveling of the optical diffraction grating as well as a movement thereof in the direction of the optical axis also hardly plays a role.
  • the light beams diffracted by the diffraction grating generate an interference pattern which is detected by the optical sensor arrangement.
  • the optical sensor arrangement can have one or more light-sensitive elements. It registers light / dark crossings of the interference pattern. In the simplest case, the amount of a relative shift of the diffraction grating can be determined by counting the registered light / dark passages on the sensor element. If the direction of the relative displacement is also to be determined with the measuring device, a plurality of sensor elements are preferably involved in the evaluation of the displacement of the interference pattern.
  • the sensor elements can, for example, be arranged offset from one another by half the width of a diffracted light beam or an interference fringes, so that one sensor or a sensor group supplies a cosine signal, while the other sensor or the other sensor group supplies a sine signal.
  • the sensors can be wider than an interference fringe.
  • Preferably four sensor elements are used, which are arranged side by side in a row and onto which the light spot formed from undiffracted light beam and diffracted light beam + 1st order and - 1st order falls. Three of the four sensor elements have a length that corresponds to the length of the light spot. This hits the sensor elements approximately in the middle, ie the two external sensor elements are just still illuminated.
  • the measuring stroke can be chosen to be very large and only depends on the length of the diffraction grating. The resolution coincides with the grid line spacing if only entire interference lines are counted. This allows high-precision measurements.
  • an analog evaluation of the signals can also be carried out.
  • the rescan can be used here so that the light / dark transitions on the individual sensor elements are not abrupt, but sinusoidal or cosine-shaped. An evaluation of the current brightness can thereby enable an interpolation of the shift between different interference lines.
  • the measuring device is preferably part of a measuring device, for example for contour or roughness measurement.
  • the measuring device then also includes a positioning device, for example a feed device, with which the sensing element and, if appropriate, the measuring device are moved together with the measuring device over the surface of the workpiece.
  • FIGS. 1 and 2 shows the optical measuring system of the measuring device according to FIGS. 1 and 2, in a schematic top view
  • FIG. 5 shows the optical measuring system according to FIG. 4, in a functional representation
  • FIG. 6 shows an evaluation device of the measuring system as a block diagram.
  • FIG. 1 illustrates a measuring device 1 which serves to determine the profile or the contour of a surface 2 of a workpiece 3. In addition, the roughness of the surface 2 can be determined.
  • the measuring device 1 has a probe element 4, e.g. a probe tip, which is movably mounted in a direction indicated by an arrow 5 approximately at right angles to the surface 2 of the workpiece 3.
  • a storage device is used for this purpose, which in the present case is formed by a pivotably mounted scanning arm 6.
  • the probe arm 6 is held on a support 6a designed as a two-armed lever, which is suspended in a pivot bearing 7 by suitable bearing means such as ball bearings, needle bearings, cutting edge bearings or springs. At its one free end it carries the feeler element 4.
  • an optical measuring arrangement 8 which registers every pivoting of the feeler arm 6 and thus every movement of the feeler element 4 in the direction of arrow 5 and in converts electrical signals. These reach an evaluation device 10 via a line 9.
  • the measuring device 1 contains a positioning device 11 which is set up to move the probe element 4 along a predetermined path over the workpiece surface 2.
  • a guide rail 12 is used, which is arranged in a housing 14 of the measuring device 1 to be arranged in a stationary manner.
  • a slide 15 is slidably mounted on the guide rail 12, which carries the bearing 7 for the probe arm 6 and the optical measuring arrangement 8. It also belongs to the Positioning device 11, an actuator 16, which is connected via a gear 17 to the slide 15 or to an element connected to the slide 15.
  • the gear means 17 can be a threaded spindle, for example, which can be rotated in a controlled manner by the actuator 16.
  • a nut seated on the threaded spindle can then be connected to the slide 15, wherein it is axially immovable and non-rotatably mounted on the slide 15.
  • Other linear drives such as toothed belts, traction cables or wires, can also be used.
  • a lifting drive 18, which can be activated as required, engages, for example via magnetic coupling, via which the probe arm 6 can be pivoted selectively, for example in order to lift the probe element 4 from the workpiece surface 2.
  • the lifting drive 18 can be used to apply a measuring force.
  • the linear drive 18 can be designed as a magnetic linear motor.
  • the measuring force can also be applied by spring means or similar devices.
  • the measuring device 1 can also do without a positioning device 11 and actuating device 16. If this is the case, an outer positioning device (not illustrated further) can be provided, which moves the entire measuring device 1 in the desired direction. This can, for example, by a 'in one or more directions controlled movable stage take place, which supports the measuring device 1.
  • FIGS. 2 and 3 show the view of a practical measuring device 1 again. Details and elements which correspond to the embodiment schematically illustrated in FIG. 1 are identified by the same reference symbols.
  • the probe arm 6 is detachably held as a removable probe arm section on the carrier 6a which is fixedly mounted on the measuring device 1.
  • a coupling device 21, which is also referred to as a magnetic scanning arm holder, is used to mount the scanning arm 6 on the carrier 6a. This is illustrated separately in FIG.
  • the carrier 6a is assigned two spherical heads 22 and a magnet which is arranged on the side of the carrier 6a facing away from the viewer in FIG.
  • a set screw 23 adjacent to the magnet has an end face with which a corresponding flat contact surface 24 on a holding part 25 of the probe arm 6 is assigned.
  • a conical recess 26 (90 "countersink) is arranged on the holding part 25 and is assigned to one of the ball heads 22.
  • a prism-shaped recess 27, which is the other one, is also used to uniquely position the probe arm 6 with respect to the carrier 6a Ball heads 22 is assigned.
  • the measuring arrangement 8 includes a light source 31, a diffraction grating 32 and a sensor arrangement 33 and, if appropriate, further optical or mechanical elements.
  • the light source 31 generates 34 capable of generating interference light a preferably convergent beam .
  • a laser diode 35 is provided, the light is transformed by a lens, in the simplest case, a condenser lens 36 to a light beam having the desired convergence (or divergence) •.
  • the Beams of light 34 are generated with convergence with respect to an optical axis 37.
  • one or more mirrors 38, 39 can be arranged in the beam path leading from the light source 31 via the diffraction grating 32 to the sensor arrangement 33. If necessary, light guide elements or other devices for light transmission can also be provided.
  • the diffraction grating 32 is directly connected to the part 6b which serves as a pivoting support and which carries the probe arm part 6a which forms the actual probe arm.
  • the diffraction grating 32 can be a simple line grating, the light-diffraction grating lines of which are oriented parallel to one another and approximately transversely to the direction of movement of the diffraction grating 32 indicated by an arrow 41 in FIG. 4a.
  • the individual grid lines can thus be oriented approximately parallel to the probe arm 6 or parallel to its axis of rotation - depending on the direction in which the light beam 34 is guided (transversely to the probe arm 6 or parallel to it).
  • the grating lines of the diffraction grating can be arranged at equal intervals or, if necessary, at alternating intervals.
  • the grid division influences the resolution and thus the linearity of the touch probe. Alternating grating divisions can serve to compensate for linearity errors that are otherwise present or to generate a desired non-linear characteristic.
  • the grid lines can also be arranged at an acute angle to one another, so that the imaginary extensions of all grid lines in the one illustrated in FIG. 4a, but somewhat modified Hit example in the axis of rotation of the bearing device 7.
  • the diffraction grating which is preferably flat, can also be curved or curved. It is arranged in the vicinity of the focus point 42 of the converging light bundle 34, so that only a few, for example only 3 or 5, grid lines are illuminated.
  • the light reflected by the diffraction grating 32 or transmitted as in the example shown forms an interference light bundle 34a which contains diffracted and undiffracted components which impinge on the sensor arrangement 33 as interfering light beams.
  • this is preferably subdivided into a plurality, for example into four elements 43, 44, 45, 46, which together form an optoelectric converter (the sensor arrangement 33).
  • the individual elements 43 to 46 of the sensor arrangement 33 are struck by an interference pattern which arises in the part of the interference light bundle 34a which has passed through the diffraction grating.
  • the fanned out light spot which is created by superimposing the 0th maximum with the + 1st maximum and the - 1st maximum, is thus larger than the light bar 44.
  • It contains a pattern of interference lines, which are indicated at 46 in FIG. They characterize the relative position of the diffraction grating 32 to the light bundle 34 or to "its optical axis.
  • the diffraction grating 32 is arranged quite close to the focus 42 or also the same, so that only relatively few lines of the grating serving as the diffraction grating 32 cause the formation of the interference pattern. This falls on the elements 43 to 46 of the sensor arrangement.
  • the light bar 46 containing the interference pattern is preferably shorter than the sensor arrangement 33, so that the external sensor cells 43, 46 are only partially covered by the superimposed light spot 46.
  • Each element 43, 44, 45, 46 is connected to a channel of an analog amplifier 47.
  • Corresponding inputs 53, 54, 55, 56 are provided for this purpose, which form a differential input in pairs (53 and 54; 55 and 56).
  • a first output signal is generated at an output 61 from the signals present at the inputs 53, 54.
  • An output 62 of the amplifier 47 outputs the amplified differential signal of the inputs 55 and 56. Due to the arrangement of the sensor cells 43, 44, 45, 46 in such a way that the pair of sensor cells 43, 44 is offset by half the interference line width from the pair of sensor cells 45, 46, there are sinusoidal out-of-phase at the outputs 61, 62 of the amplifier 47 Signals on.
  • the signals of the outputs 61, 62 are passed on to trigger stages 63, 64, which convert the sin signals into rectangular signals.
  • a downstream up / down counter 65 contains the triggered sine and cosine signals and counts them. The 90 ° phase offset between the sine and the cosine signal makes it possible to determine the direction clearly, so that the up / down counter 65 increments or decrements its count value in accordance with the direction of movement of the diffraction grating 32.
  • Analog / digital converter stages 66, 67 are connected in parallel with the trigger stages 63, 64 and convert the current signal value of the outputs 61, 62 into digital values. The digital values obtained in this way are indicative of the current difference in brightness between the sensor cells 43, 44 and correspondingly 45, 46.
  • the outputs of the up / down counter 65 and the evaluation circuit 68 connected to the analog / digital converters 67, 66 are connected to a combining stage 69 which contains the number of steps specified by the up / down counter stage 65 and the output from the evaluation circuit 68 Intermediate step value added to get a measured value. This is output at an output 70.
  • the measuring device 1 described so far operates as follows:
  • the probe arm 6 is guided with the probe element 4 over the surface 2 of the workpiece 3.
  • the setting device 16 is actuated, for example, in the measuring device according to FIG.
  • the feeler element 4 follows the contour and the roughness of the surface 2, whereby the feeler arm 6 is deflected accordingly.
  • the movement of the probe arm 6 is transmitted to the diffraction grating 32, which is moved in accordance with the deflection of the probe element 4.
  • the diffraction grating 32 is thus displaced relative to the light bundle 34 or its optical axis.
  • the interference lines of the light spot 46 pass through the sensor arrangement 33. Each interference line generates a sine wave at the outputs 31, 32.
  • the counting content of the up / down counter 65 reflects the number of the interference lines passed, depending on the direction.
  • the intermediate values are determined with the evaluation circuit 68.
  • the combiner 69 thus outputs a position signal at its output that precisely identifies the current deflection of the sensing element 4.
  • the illustrated optical interference sensor can not only be used for one-dimensional measurement tasks, but also, if necessary, for two-dimensional measurement tasks.
  • two line grids rotated by 90 ° with respect to one another are used to generate the interference image and can be moved either independently of one another or together.
  • a point grid can also be used.
  • the point grid can be formed by circular or otherwise shaped points on a translucent or light-reflecting surface.
  • the inverse arrangement, in which the points are transparent or reflective and the remaining surface is opaque or non-reflective, can also be used. On the sensor side, it is then not a linear sensor as indicated in FIG.
  • An optical interference measuring device for detecting and tracking the movement of a mechanical element 4 has a light source 31 for emitting a light beam capable of interference, as well as a diffraction grating and a sensor arrangement 33.
  • a beam path leads from the light source via the diffraction grating 32 to the sensor arrangement 33.
  • the diffraction grating divides the light bundle into at least three sub-components, so that on the optical sensor arrangement 33 a light spot with three overlapping maxima, the mean zero maximum and the minus lying on both sides thereof first and plus first maximum arises.
  • the light beams for generating the three brightness maxima interfere with one another, so that the resulting superimposed light spot contains 46 interference lines that run in one direction or another when the diffraction grating is moved.
  • the movement of the interference lines is detected by the sensor arrangement 33 and evaluated in an evaluation circuit. This enables the precise detection of every movement of the diffraction grating 32.
  • almost all of the interference image to be generated by the light source is used. Bright interference images thus arise even at low light outputs of the light source 31. Components of low output can therefore be used.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

A measuring device using interference optics, for detecting and tracking the movement of a mechanical element (4) has a light source (31) for emitting a light bundle that is capable of interference, a diffraction grating and a sensor arrangement (33). A beam path leads from the light source to the sensor arrangement (33) via the diffraction grating (32). Said diffraction grating divides the light bundle into at least three partial components, so that a light patch with three overlapping peaks, the middle, zero peak and the minus one and plus one peaks either side thereof, is formed. The light beams producing the three brightness peaks interfere with each other so that the resulting superimposed luminous spot (46) contains interference bands which run in one direction or another when the diffraction grating is moved. The movement of the interference bands is detected with the sensor arrangement (33) and evaluated in an evaluation circuit. This enables each movement of the diffraction grating (32) to be detected precisely. The arrangement makes use of almost the entire interference figure generated by the light from the light source. As a result, light-intensive interference figures can be produced even with low capacities of the light source (31). This enables low-capacity components to be used.

Description

TASTER MIT BEUGUNGSGITTER FÜR +1, 0 UND -1 ORDNUNGEN BUTTON WITH diffraction grating for +1, 0 and -1 orders
Die Erfindung betrifft eine Messeinrichtung, die insbesondere zur Messung der Oberflächenrauheit und/oder der Oberflächenkontur eines Werkstücks vorgesehen ist.The invention relates to a measuring device which is provided in particular for measuring the surface roughness and / or the surface contour of a workpiece.
Die Vermessung von Werkstücken und die Bestimmung spezieller Oberflächeneigenschaften wie Rauheit, Formhal- tigkeit (Kontur) und ähnliche Messaufgaben werden häufig gelöst, indem die Oberfläche oder zu vermessende Oberflächenbereiche mechanisch angetastet werden. Dazu sind verschiedene Tastkörper wie Kugeln, Messspitzen, Diamantspitzen oder ähnliches in Gebrauch - je nach Messaufgabe. Wäh- rend die mechanische Vermessung meist durch punktweises Antasten der Werkstückoberfläche erfolgt, ist es zur Bestimmung der Oberflächenrauheit oder der Oberflächenkontur oder von Formelementen eines Werkstücks üblich, eine Tastspitze, bspw. eine Diamantspitze oder eine Stahlspitze, über eine festgelegte Wegstrecke mit festgelegter Geschwindigkeit zu schleppen und die im Wesentlichen rechtwinklig zu der Werkstückoberfläche erfolgenden Auslenkungen der Tastspitze aufzuzeichnen bzw. auszuwerten. Voraussetzung ist immer die Erfassung der Bewegung bzw. Auslenkung des Tastelements. Hierzu sind hoch auflösende und schnell arbeitende Linearmesssysteme (sogenannte Wegaufnehmer) oder verwandte Messsysteme erforderlich. Soll die Rauheitsmessung mit einer Konturmessung kombiniert werden oder nur eine Konturmessung durchgeführt werden, durchläuft das Tastelement bei dem Messvorgang in der Regel relativ große Hübe. Diese sollen möglichst innerhalb des Messbereichs des entsprechenden Messsystems liegen.The measurement of workpieces and the determination of special surface properties such as roughness, form stability (contour) and similar measuring tasks are often solved by mechanically probing the surface or surface areas to be measured. Various probes such as spheres, measuring tips, diamond tips or the like are used for this - depending on the measuring task. currency While the mechanical measurement is usually carried out by touching the workpiece surface point by point, it is customary to determine the surface roughness or the surface contour or shape elements of a workpiece by dragging a probe tip, e.g. a diamond tip or a steel tip, over a specified distance at a specified speed and that to record or evaluate deflections of the probe tip that occur essentially at right angles to the workpiece surface. The prerequisite is always the detection of the movement or deflection of the probe element. This requires high-resolution and fast-working linear measuring systems (so-called displacement transducers) or related measuring systems. If the roughness measurement is to be combined with a contour measurement or if only one contour measurement is to be carried out, the probe element generally runs through relatively large strokes during the measurement process. As far as possible, these should lie within the measuring range of the corresponding measuring system.
Zur Messung linearer Verschiebungen sind bspw. induktive Messsysteme bekannt. Diese geben in der Regel ein der Auslenkung proportionales Signal ab und müssen deshalb als Analog-Messsysteme gelten. Darüber hinaus sind sogenannte inkrementale Geber bekannt, die auch auf optischen Prinzipien beruhen können. Bspw. ist aus der DE 19712622 AI eine Auswerteeinrichtung für eine optisch abgetastete Maßstabteilung bekannt. Das optische Messsystem erzeugt zwei Signale Sl, S2, die als Abtastsignale der Auswerteeinheit zugeleitet werden. Die Abtastsignale sind um 90° phasenversetzt und periodisch. Die Signale werden über einen Analog/Digital-Wandler geleitet. Die Anzahl der durchlaufenen Maxima kennzeichnet eine Schrittzahl und der präzise Signalwert den über die Schrittzahl hinaus durchlaufenen Weg. Die genannte Offenlegungsschrift befasst sich jedoch nicht mit der Art der Signalgewinnung. Vielmehr werden sowohl optische als auch magnetische Maßstäbe und somit auch Sensoren in Betracht gezogen.For example, inductive measuring systems are known for measuring linear displacements. As a rule, these emit a signal proportional to the deflection and must therefore be regarded as analog measuring systems. In addition, so-called incremental encoders are known, which can also be based on optical principles. For example. DE 19712622 AI an evaluation device for an optically scanned scale division is known. The optical measuring system generates two signals S1, S2, which are fed to the evaluation unit as scanning signals. The scanning signals are 90 ° out of phase and periodic. The signals are routed via an analog / digital converter. The number of maxima passed indicates a number of steps and the precise signal value indicates the path traveled beyond the number of steps. However, the aforementioned disclosure document deals with not with the type of signal acquisition. Rather, both optical and magnetic scales and thus sensors are taken into account.
Aus der DE 19652563 AI ist eine lichtelektrische Positionsmesseinrichtung bekannt, zu der eine Lichtquelle, ein ruhendes Beugungsgitter, das als Strahlteiler dient, und ein bewegtes Beugungsgitter gehören. Das erste Beugungsgitter gibt gebeugte Lichtstrahlen + 1. Ordnung und - 1. Ordnung ab. Diese Lichtstrahlen treffen das bewegte Beugungsgitter, das die Teilstrahlen + 1. Ordnung und - 1. Ordnung zurückreflektiert. Sie durchlaufen nochmals den Strahlteiler und werden zur Interferenz gebracht. Das bewegte und als Maßstab dienende Beugungsgitter wird somit von zerlegtem, in mehrere Teilstrahlen aufgefächerten, Licht getroffen. Nur ein Teil des aufgefächerten Lichts wird von dem als Strahlteiler dienenden Beugungsgitter wieder zusam engef sst und zur Interferenz gebracht.From DE 19652563 AI a photoelectric position measuring device is known, which includes a light source, a stationary diffraction grating, which serves as a beam splitter, and a moving diffraction grating. The first diffraction grating emits diffracted light rays + 1st order and - 1st order. These light rays hit the moving diffraction grating, which reflects the partial rays + 1st order and - 1st order back. They run through the beam splitter again and are brought to interference. The moving diffraction grating, which serves as a scale, is thus struck by light that has been broken down and fanned out into several partial beams. Only part of the fanned out light is gathered together by the diffraction grating, which serves as a beam splitter, and brought to interference.
Ein abweichendes Messprinzip zur Positionsmessung ist aus der EP 0586454 Bl bekannt. Hier wird ein Beugungsgitter mit einem parallelen interferenzfähigen Lichtbündel beleuchtet. Die zurückgestreuten Lichtbündel - 1. Ordnung und + 1. Ordnung werden über einen Strahlteiler wechselweise miteinander zur Interferenz gebracht und die Interferenzbilder werden von jeweils eigenen Detektoren ausgewertet.A different measuring principle for position measurement is known from EP 0586454 B1. Here a diffraction grating is illuminated with a parallel light beam capable of interference. The backscattered light beams - 1st order and + 1st order are alternately brought into interference with each other via a beam splitter and the interference images are evaluated by their own detectors.
Die Positionsbestimmung des Maßstabs erfolgt ausschließlich anhand der gebeugten Strahlen + 1. Ordnung und - 1. Ordnung. Diese tragen nur einen Teil der eingesetzten Lichtenergie. Davon ausgehend ist es Aufgabe der Erfindung, einen optischen Positionssensor, anzugeben, der eine gute Lichtausnutzung ermöglicht.The position of the scale is determined exclusively using the diffracted beams + 1st order and - 1st order. These only carry part of the light energy used. Based on this, it is an object of the invention to provide an optical position sensor which enables good light utilization.
Diese Aufgabe wird mit einer Messeinrichtung gelöst, die die Merkmale des Patentanspruchs 1 aufweist.This object is achieved with a measuring device which has the features of patent claim 1.
Die erfindungsgemäße Messeinrichtung weist ein Beugungsgitter auf, das von einem interferenzfähigen Lichtbündel getroffen wird. Das Beugungsgitter erzeugt einen ungebeugten Lichtstrahl sowie mehrere gebeugte Lichtstrahlen, von denen der gebeugte Lichtstrahl + 1. Ordnung und der gebeugte Lichtstrahl - 1. Ordnung gemeinsam mit dem ungebeugten Lichtstrahl (0. Ordnung), der das Beugungsgitter passiert hat, zur Erzeugung eines Interferenzbilds herangezogen werden. Die Strahlmaxima nulltes Maximum, plus erstes Maximum und minus erstes Maximum überdecken sich dabei teilweise, so dass ein insgesamt helles Interferenzmuster schon bei lichtquellengeringster Leistung erzeugbar ist. Dadurch können sehr leistungsschwache Laserdioden zur Erzeugung des interferenzfähigen Lichtbündels verwendet werden. Dies hat den Vorteil eines sehr geringen Wärmeeintrags in die gesamte Messeinrichtung, was wiederum deren Genauigkeit erhöht. Fehler infolge von thermischen Ausdehnungen, infolge von Temperaturerhöhungen können bspw. reduziert oder ausgeschlossen werden. Das gesamte Messsystem kann sehr klein gebaut werden. Auf eine thermische Trennung von Lichtquelle, Beugungsgitter und Sensoren kommt es kaum noch an.The measuring device according to the invention has a diffraction grating which is hit by a light beam capable of interference. The diffraction grating generates an undiffracted light beam as well as several diffracted light beams, of which the diffracted light beam + 1st order and the diffracted light beam - 1st order together with the undiffracted light beam (0th order) that has passed through the diffraction grating are used to generate an interference image become. The beam maxima zero maximum, plus first maximum and minus first maximum partially overlap, so that an overall bright interference pattern can be generated even with the lowest light source power. As a result, very low-power laser diodes can be used to generate the light beam capable of interference. This has the advantage of a very low heat input into the entire measuring device, which in turn increases its accuracy. Errors due to thermal expansion, as a result of temperature increases, can be reduced or eliminated, for example. The entire measuring system can be built very small. A thermal separation of light source, diffraction grating and sensors is hardly important.
Die Messeinrichtung gestattet eine hohe Auflösung. Diese kann durch Änderung der Gitterkonstante des Beugungsgitter sowie des Abstands zwischen der Lichtquelle und dem Beugungsgitter beeinflusst werden, wenn mit einem nicht parallelen interferenzfähigen Lichtbündel gearbeitet wird. Vorzugsweise wird das von der Lichtquelle ausgesendete Lichtbündel über eine entsprechende optische Einrichtung (Optik) fokussiert und das Beugungsgitter wird in der Nähe des Fokuspunkts (Brennpunkt) oder genau auf diesem angeordnet. Dabei ist das Beugungsgitter vorzugsweise quer zu dem Lichtstrahl ausgerichtet. Das Beugungsgitter muss jedoch nicht zwingend präzise rechtwinklig zu dem Lichtstrahl angeordnet sein. Kleinere Abweichungen vom rechten Winkel stören nicht oder kaum. Auch spielt eine Verdrehung oder Verschwenkung des optischen Beugungsgitters sowie eine Bewegung desselben in Richtung der optischen Achse kaum eine Rolle.The measuring device allows a high resolution. This can be influenced by changing the grating constant of the diffraction grating and the distance between the light source and the diffraction grating, if with a non-parallel interference-capable light beam is worked. The light bundle emitted by the light source is preferably focused via a corresponding optical device (optics) and the diffraction grating is arranged in the vicinity of the focus point (focal point) or precisely on this. The diffraction grating is preferably aligned transversely to the light beam. However, the diffraction grating does not necessarily have to be arranged precisely at right angles to the light beam. Smaller deviations from the right angle do not interfere or hardly. A rotation or swiveling of the optical diffraction grating as well as a movement thereof in the direction of the optical axis also hardly plays a role.
Die von dem Beugungsgitter gebeugten Lichtstrahlen erzeugen ein Interferenzmuster, das von der optischen Sensoranordnung erfasst wird. Die optische Sensoranordnung kann ein oder mehrere lichtempfindliche Elemente aufweisen. Sie registriert Hell-/Dunkeldurchgänge des Interferenzmusters. Im einfachsten Fall kann durch Auszählen der registrierten Hell-/Dunkeldurchgänge an dem Sensorelement der Betrag einer Relativverschiebung des Beugungsgitters bestimmt werden. Soll mit der Messeinrichtung außerdem die Richtung der Relativverschiebung bestimmt werden, sind an der Auswertung der Verschiebung des Interferenzmusters vorzugsweise mehrere Sensorelemente beteiligt. Die Sensorelemente können bspw. um die halbe Breite eines gebeugten Lichtstrahls oder eines Interferenzstreifens gegeneinander versetzt angeordnet sein, so dass ein Sensor oder eine Sensorgruppe ein Kosinussignal liefert, während der andere Sensor oder die andere Sensorgruppe ein Sinussignal liefert. Die Sensoren dürfen dabei breiter sein als ein Interferenzstreifen. Vorzugsweise werden vier Sensorelemente verwendet, die nebeneinander in einer Reihe angeordnet sind und auf die der aus ungebeugtem Lichtstrahl sowie gebeugten Lichtstrahl + 1. Ordnung und - 1. Ordnung gebildete Lichtfleck fällt. Drei der vier Sensorelemente nehmen eine Länge ein, die mit der Länge des Lichtflecks übereinstimmt. Dieser trifft die Sensorelemente etwa mittig, d.h. die beiden außenständigen Sensorelemente werden gerade noch beleuchtet. Der Meßhub kann sehr groß gewählt werden und hängt nur von der Länge des Beugungsgitters ab. Die Auflösung stimmt dabei, wenn nur ganze Interferenzlinien gezählt werden, mit dem Gitterlinienabstand überein. Dies erlaubt hochpräzise Messungen.The light beams diffracted by the diffraction grating generate an interference pattern which is detected by the optical sensor arrangement. The optical sensor arrangement can have one or more light-sensitive elements. It registers light / dark crossings of the interference pattern. In the simplest case, the amount of a relative shift of the diffraction grating can be determined by counting the registered light / dark passages on the sensor element. If the direction of the relative displacement is also to be determined with the measuring device, a plurality of sensor elements are preferably involved in the evaluation of the displacement of the interference pattern. The sensor elements can, for example, be arranged offset from one another by half the width of a diffracted light beam or an interference fringes, so that one sensor or a sensor group supplies a cosine signal, while the other sensor or the other sensor group supplies a sine signal. The sensors can be wider than an interference fringe. Preferably four sensor elements are used, which are arranged side by side in a row and onto which the light spot formed from undiffracted light beam and diffracted light beam + 1st order and - 1st order falls. Three of the four sensor elements have a length that corresponds to the length of the light spot. This hits the sensor elements approximately in the middle, ie the two external sensor elements are just still illuminated. The measuring stroke can be chosen to be very large and only depends on the length of the diffraction grating. The resolution coincides with the grid line spacing if only entire interference lines are counted. This allows high-precision measurements.
Soll die Auflösung noch höher sein als durch reines Zählen der an einem Sensorelement vorbeilaufenden Interferenzlinien möglich, kann zusätzlich eine Analogauswertung der Signale vorgenommen werden. Hier kann der Umscand genutzt werden, dass die Hell-/Dunkelübergänge an den einzelnen Sensorelementen nicht abrupt, sondern sinus- oder kosinusförmig verlaufen. Eine Auswertung der aktuellen Helligkeit kann dadurch eine Interpolation der Verschiebung zwischen verschiedenen Interferenzlinien ermöglichen.If the resolution is to be even higher than possible simply by counting the interference lines running past a sensor element, an analog evaluation of the signals can also be carried out. The rescan can be used here so that the light / dark transitions on the individual sensor elements are not abrupt, but sinusoidal or cosine-shaped. An evaluation of the current brightness can thereby enable an interpolation of the shift between different interference lines.
Die Messeinrichtung ist vorzugsweise Teil eines Messgeräts, bspw. zur Kontur oder Rauheitsmessung. Zu dem Messgerät gehört dann auch eine Positionierungseinrichtung, bspw. eine Vorschubeinrichtung, mit der das Tastelement und ggfs. mit diesem geraeinsam die Messeinrichtung über die Oberfläche des Werkstücks bewegt werden.The measuring device is preferably part of a measuring device, for example for contour or roughness measurement. The measuring device then also includes a positioning device, for example a feed device, with which the sensing element and, if appropriate, the measuring device are moved together with the measuring device over the surface of the workpiece.
Weitere Einzelheiten vorteilhafter Ausführungsformen der Erfindung sind Gegenstand von Unteransprüchen, der Zeichnung oder der Beschreibung. In der Zeichnung ist ein Ausführungsbeispiel der Erfindung veranschaulicht. Es zeigen: Fig. 1 ein Messgerät mit einem optischen Messsystem an einem Werkstück, in schematischer Prinzipdarstellung,Further details of advantageous embodiments of the invention are the subject of dependent claims, the drawing or the description. An exemplary embodiment of the invention is illustrated in the drawing. Show it: 1 shows a measuring device with an optical measuring system on a workpiece, in a schematic basic illustration,
Fig. 2 das Messgerät nach Figur 1, in einer perspektivischen Gesamtansicht und ohne Gehäuse,2 the measuring device according to FIG. 1, in a perspective overall view and without a housing,
Fig. 3 die Lagerung des Tastarms des Messgeräts nach Figur 2, in perspektivischer Explosionsdarstellung,3 the storage of the probe arm of the measuring device according to FIG. 2, in a perspective exploded view,
Fig. 4 das optische Messsystem des Messgeräts nach Figur 1 und 2, in schematischer Draufsicht,4 shows the optical measuring system of the measuring device according to FIGS. 1 and 2, in a schematic top view,
Fig. 4a Tastarm und Beugungsgitter des optischen Messsystems nach Figur 4, in einer schematisierten Seitenansicht,4a probe arm and diffraction grating of the optical measuring system according to FIG. 4, in a schematic side view,
Fig. 5 das optische Messsystem nach Figur 4, in einer Funktionsdarstellung, und5 shows the optical measuring system according to FIG. 4, in a functional representation, and
Fig. 6 eine Auswerteeinrichtung des Messsystems als Blockschaltbild. 6 shows an evaluation device of the measuring system as a block diagram.
In Figur 1 ist eine Messeinrichtung 1 veranschaulicht, die zur Bestimmung des Profils oder der Kontur einer Oberfläche 2 eines Werkstücks 3 dient. Zusätzlich kann die Rauheit der Oberfläche 2 bestimmt werden. Die Messeinrichtung 1 weist ein Tastelement 4, z.B. eine Tastspitze, auf, das in einer durch einen Pfeil 5 bezeichneten Richtung etwa rechtwinklig zu der Oberfläche 2 des Werkstücks 3 bewegbar gelagert ist. Dazu dient eine Lagereinrichtung, die im vorliegenden Fall durch einen schwenkbar gelagerten Tastarm 6 gebildet wird. Der Tastarm 6 ist an einem als zweiarmiger Hebel ausgebildeten Träger 6a gehalten, der bei einer Schwenklagerung 7 durch geeignete Lagermittel wie Kugellager, Nadellager, Schneidenlagerungen oder Federn aufgehängt ist. An seinem einen freien Ende trägt er das Tastelement 4. An dem davon abliegenden freien Ende des Trägers 6a ist dieser mit einer optischen Messanordnung 8 verbunden, die jede Verschwenkung des Tastarms 6 und somit jede Bewegung des Tastelements 4 in Richtung des Pfeils 5 registriert und in elektrische Signale umsetzt. Diese gelangen über eine Leitung 9 an ein Auswertegerät 10.FIG. 1 illustrates a measuring device 1 which serves to determine the profile or the contour of a surface 2 of a workpiece 3. In addition, the roughness of the surface 2 can be determined. The measuring device 1 has a probe element 4, e.g. a probe tip, which is movably mounted in a direction indicated by an arrow 5 approximately at right angles to the surface 2 of the workpiece 3. A storage device is used for this purpose, which in the present case is formed by a pivotably mounted scanning arm 6. The probe arm 6 is held on a support 6a designed as a two-armed lever, which is suspended in a pivot bearing 7 by suitable bearing means such as ball bearings, needle bearings, cutting edge bearings or springs. At its one free end it carries the feeler element 4. At the free end of the support 6a remote therefrom it is connected to an optical measuring arrangement 8 which registers every pivoting of the feeler arm 6 and thus every movement of the feeler element 4 in the direction of arrow 5 and in converts electrical signals. These reach an evaluation device 10 via a line 9.
um mit der Messeinrichtung 1 die Oberflächenkontur und/oder die Oberflächenrauheit der Oberfläche 2 des Werkstücks 3 bestimmen zu können, enthält die Messeinrichtung 1 eine Positionierungseinrichtung 11, die dazu eingerichtet ist, das Tastelement 4 entlang eines vorbestimmten Wegs über die Werkstückoberfläche 2 zu bewegen. Dazu dient eine Führungsschiene 12, die in einem Gehäuse 14 der ortsfest anzuordnenden Messeinrichtung 1 angeordnet ist. An der Führungsschiene 12 ist ein Schlitten 15 verschiebbar gelagert, der die Lagerung 7 für den Tastarm 6 und die optische Messanordnung 8 trägt. Außerdem gehört zu der Positionierungseinrichtung 11 ein Stellantrieb 16, der über ein Getriebemittel 17 mit dem Schlitten 15 oder einem mit dem Schlitten 15 verbundenen Element verbunden ist. Das Getriebemittel 17 kann bspw. eine Gewindespindel sein, die von dem Stellantrieb 16 gesteuert in Drehung versetzt werden kann. Eine auf der Gewindespindel sitzende Mutter kann dann mit dem Schlitten 15 verbunden sein, wobei sie an dem Schlitten 15 axial unverschiebbar und unverdrehbar gelagert ist. Andere Linearantriebe, wie bspw. Zahnriemen, Zugseile oder Drähte sind ebenfalls anwendbar.In order to be able to determine the surface contour and / or the surface roughness of the surface 2 of the workpiece 3 with the measuring device 1, the measuring device 1 contains a positioning device 11 which is set up to move the probe element 4 along a predetermined path over the workpiece surface 2. For this purpose, a guide rail 12 is used, which is arranged in a housing 14 of the measuring device 1 to be arranged in a stationary manner. A slide 15 is slidably mounted on the guide rail 12, which carries the bearing 7 for the probe arm 6 and the optical measuring arrangement 8. It also belongs to the Positioning device 11, an actuator 16, which is connected via a gear 17 to the slide 15 or to an element connected to the slide 15. The gear means 17 can be a threaded spindle, for example, which can be rotated in a controlled manner by the actuator 16. A nut seated on the threaded spindle can then be connected to the slide 15, wherein it is axially immovable and non-rotatably mounted on the slide 15. Other linear drives, such as toothed belts, traction cables or wires, can also be used.
An den mit der optischen Messanordnung 8 verbundenen Ende des Tastarms 6 greift, bspw. über magnetische Kupplung, ein bedarfsweise aktivierbarer Hubantrieb 18 an, über den der Tastarm 6 gezielt verschwenkt werden kann, bspw. um das Tastelement 4 von der Werkstückoberfläche 2 abzuheben. Außerdem kann der Hubantrieb 18 dazu herangezogen werden, eine Messkraft aufzubringen. Dazu kann der Hubantrieb 18 als magnetischer Linearmotor ausgebildet sein. Alternativ kann die Messkraft auch durch Federmittel oder ähnliche Einrichtungen aufgebracht werden.At the end of the probe arm 6 connected to the optical measuring arrangement 8, a lifting drive 18, which can be activated as required, engages, for example via magnetic coupling, via which the probe arm 6 can be pivoted selectively, for example in order to lift the probe element 4 from the workpiece surface 2. In addition, the lifting drive 18 can be used to apply a measuring force. For this purpose, the linear drive 18 can be designed as a magnetic linear motor. Alternatively, the measuring force can also be applied by spring means or similar devices.
Anders als bei dem in Figur 1 veranschaulichten Ausführungsbeispiel kann die Messeinrichtung 1 auch ohne Positioniereinrichtung 11 und Stelleinrichtung 16 auskommen. Ist dies der Fall, kann eine nicht weiter veranschaulichte äußere Positioniervorrichtung vorgesehen werden, die die gesamte Messeinrichtung 1 in der gewünschten Richtung bewegt. Dies kann bspw. durch einen' in ein- oder mehreren Richtungen gesteuert bewegbaren Träger erfolgen, der die Messeinrichtung 1 trägt.In contrast to the exemplary embodiment illustrated in FIG. 1, the measuring device 1 can also do without a positioning device 11 and actuating device 16. If this is the case, an outer positioning device (not illustrated further) can be provided, which moves the entire measuring device 1 in the desired direction. This can, for example, by a 'in one or more directions controlled movable stage take place, which supports the measuring device 1.
Während die Messeinrichtung 1 in Figur 1 relativ schematisch veranschaulicht ist, geben die Figuren 2 und 3 die Ansicht einer praktisch ausgeführten Messeinrichtung 1 wieder. Einzelheiten und Elemente die mit der in Figur 1 schematisch veranschaulichten Ausführungsform übereinstimmen, sind mit gleichen Bezugszeichen bezeichnet. Wie Figur 3 veranschaulicht, ist der Tastarm 6 als abnehmbarer Tastarmabschnitt lösbar an dem fest an der Messeinrichtung 1 montierten Träger 6a gehalten. Zur Lagerung des Tastarms 6 an dem Träger 6a dient eine auch als magnetische Tastarm- halterung bezeichnete Kupplungseinrichtung 21. Diese ist in Figur 3 gesondert veranschaulicht. Dem Träger 6a sind zwei Kugelköpfe 22 und ein Magnet zugeordnet, der an der in Figur 3 dem Betrachter abgewandten Seite des Trägers 6a angeordnet ist. Eine dem Magneten benachbarte Stellschraube 23 weist eine Stirnfläche auf, der eine entsprechende plane Anlagefläche 24 an einem Halterungsteil 25 des Tastarms 6 zugeordnet ist. Außerdem ist an dem Halterungsteil 25 eine kegelförmige Ausnehmung 26 (90 "-Senkung) angeordnet, die einer der Kugelköpfe 22 zugeordnet ist. Zur eindeutigen Positionierung des Tastarms 6 in Bezug auf den Träger 6a dient außerdem eine pris enförmige Ausnehmung 27, der der andere der Kugelköpfe 22 zugeordnet ist.While the measuring device 1 is illustrated relatively schematically in FIG. 1, FIGS. 2 and 3 show the view of a practical measuring device 1 again. Details and elements which correspond to the embodiment schematically illustrated in FIG. 1 are identified by the same reference symbols. As illustrated in FIG. 3, the probe arm 6 is detachably held as a removable probe arm section on the carrier 6a which is fixedly mounted on the measuring device 1. A coupling device 21, which is also referred to as a magnetic scanning arm holder, is used to mount the scanning arm 6 on the carrier 6a. This is illustrated separately in FIG. The carrier 6a is assigned two spherical heads 22 and a magnet which is arranged on the side of the carrier 6a facing away from the viewer in FIG. A set screw 23 adjacent to the magnet has an end face with which a corresponding flat contact surface 24 on a holding part 25 of the probe arm 6 is assigned. In addition, a conical recess 26 (90 "countersink) is arranged on the holding part 25 and is assigned to one of the ball heads 22. A prism-shaped recess 27, which is the other one, is also used to uniquely position the probe arm 6 with respect to the carrier 6a Ball heads 22 is assigned.
Eine wesentliche Besonderheit der Messeinrichtung 1 liegt in der Ausbildung der optischen Messanordnung 8. Diese ist in Figur 4 und Figur 4a schematisch veranschaulicht. Zu der Messanordnung 8 gehören eine Lichtquelle 31, ein Beugungsgitter 32 und eine Sensoranordnung 33 sowie ggfs. weitere optische oder mechanische Elemente. Die Lichtquelle 31 erzeugt einen vorzugsweise konvergenten Strahl 34 interferenzfähigen Lichts.. Dazu ist eine Laserdiode 35 vorgesehen, deren Licht durch ein Objektiv, im einfachsten Fall eine Sammellinse 36, zu einem Lichtbündel mit der gewünschten Konvergenz (oder Divergenz) • umgeformt wird. In dem hier bevorzugten Ausführungsbeispiel wird das Lichtbündel 34 mit Konvergenz bezüglich einer optischen Achse 37 erzeugt. Um die Messanordnung 8 möglichst kompakt auszubilden, können in dem Strahlengang, der von der Lichtquelle 31 über das Beugungsgitter 32 zu der Sensoranordnung 33 führt, ein oder mehrere Spiegel 38, 39 angeordnet sein. Bedarfsweise können auch Lichtleitelemente oder andere Einrichtungen zur Lichtübertragung vorgesehen sein.An essential special feature of the measuring device 1 lies in the design of the optical measuring arrangement 8. This is illustrated schematically in FIG. 4 and FIG. 4a. The measuring arrangement 8 includes a light source 31, a diffraction grating 32 and a sensor arrangement 33 and, if appropriate, further optical or mechanical elements. The light source 31 generates 34 capable of generating interference light a preferably convergent beam .. For this purpose, a laser diode 35 is provided, the light is transformed by a lens, in the simplest case, a condenser lens 36 to a light beam having the desired convergence (or divergence) •. In the preferred embodiment here, the Beams of light 34 are generated with convergence with respect to an optical axis 37. In order to make the measuring arrangement 8 as compact as possible, one or more mirrors 38, 39 can be arranged in the beam path leading from the light source 31 via the diffraction grating 32 to the sensor arrangement 33. If necessary, light guide elements or other devices for light transmission can also be provided.
Das Beugungsgitter 32 ist unmittelbar mit dem als Schwenkträger dienenden Teil 6b verbunden, das den Tastarmteil 6a trägt, der den eigentlichen Tastarm bildet. Das Beugungsgitter 32 kann ein einfaches Strichgitter sein, dessen lichtbeugende Gitterlinien parallel zueinander und etwa quer zu der in Figur 4a durch einen Pfeil 41 bezeichneten Bewegungsrichtung des Beugungsgitters 32 orientiert sind. Die einzelnen Gitterlinien können somit sowohl etwa parallel zu dem Tastarm 6 oder parallel zu seiner Drehachse orientiert sein - je nachdem in welcher Richtung das Lichtbündel 34 geführt wird (quer zu dem Tastarm 6 oder parallel zu diesem) .The diffraction grating 32 is directly connected to the part 6b which serves as a pivoting support and which carries the probe arm part 6a which forms the actual probe arm. The diffraction grating 32 can be a simple line grating, the light-diffraction grating lines of which are oriented parallel to one another and approximately transversely to the direction of movement of the diffraction grating 32 indicated by an arrow 41 in FIG. 4a. The individual grid lines can thus be oriented approximately parallel to the probe arm 6 or parallel to its axis of rotation - depending on the direction in which the light beam 34 is guided (transversely to the probe arm 6 or parallel to it).
Die Gitterlinien des Beugungsgitters können in gleichen Abständen oder bedarfsweise auch in wechselnden Abständen angeordnet werden. Die Gitterteilung beeinflusst die Auflösung und somit die Linearität des Tastsystems. Wechselnde Gitterteilungen können dazu dienen, sonst vorhandene Linearitätsfehler auszugleichen oder eine gewünschte nichtlineare Kennlinie zu erzeugen.The grating lines of the diffraction grating can be arranged at equal intervals or, if necessary, at alternating intervals. The grid division influences the resolution and thus the linearity of the touch probe. Alternating grating divisions can serve to compensate for linearity errors that are otherwise present or to generate a desired non-linear characteristic.
Die Gitterlinien können bedarfsweise auch spitzwinklig zueinander angeordnet sein, so dass sich die gedachten Verlängerungen aller Gitterlinien bei dem in Figur 4a veranschaulichten, jedoch etwas abgewandelten Beispiel in der Drehachse der Lagereinrichtung 7 treffen. Ebenso kann das Beugungsgitter, das vorzugsweise eben ausgebildet ist, auch gewölbt oder gekrümmt ausgebildet sein. Es ist in der Nähe des Fokuspunkts 42 des konvergierenden Lichtbündels 34 angeordnet, so dass nur wenige, z.B. nur 3 oder 5, Gitterlinien beleuchtet werden.If necessary, the grid lines can also be arranged at an acute angle to one another, so that the imaginary extensions of all grid lines in the one illustrated in FIG. 4a, but somewhat modified Hit example in the axis of rotation of the bearing device 7. Likewise, the diffraction grating, which is preferably flat, can also be curved or curved. It is arranged in the vicinity of the focus point 42 of the converging light bundle 34, so that only a few, for example only 3 or 5, grid lines are illuminated.
Das von dem Beugungsgitter 32 reflektierte oder wie im dargestellten Beispiel durchgelassene Licht bildet ein Interferenzlichtbündel 34a, das gebeugte und ungebeugte Anteile enthält, die als interferierende Lichtstrahlen auf die Sensoranordnung 33 treffen. Diese ist, wie bspw. Figur 6 veranschaulicht, vorzugsweise in mehrere, bspw. in vier Elemente 43, 44, 45, 46 unterteilt, die gemeinsam einen optoelektrischen Wandler (die Sensoranordnung 33) bilden. Die einzelnen Elemente 43 bis 46 der Sensoranordnung 33 werden von einem Interferenzmuster getroffen, das in dem Teil des Interferenzlichtbündels 34a entsteht, der das Beugungsgitter passiert hat. Wie in Figur 5 angedeutet, ist parallel zur optischen Achse ein erstes Helligkeitsmaximum vorhanden, das einen ungebeugten Strahlanteil darstellt. Rechts und links (in Figur 5 oberhalb und unterhalb) des ungebeugten Strahls ist ein + 1. Maximum und ein - 1. Maximum vorhanden. Der in Figur 5 links dargestellte Lichtbalken (balkenförmiger Lichtfleck) 44, der von der Laserdiode 35 und dem Objektiv 36 erzeugt wird, wird somit durch Beugung aufgefächert. Der aufgefächerte Lichtfleck, der durch Überlagerung des 0. Maximums mit dem + 1. Maximum und dem - 1. Maximum entsteht, ist somit größter als der Lichtbalken 44. Er enthält ein Muster von Interferenzlinien, die in Figur 5 bei 46 angedeutet sind. Sie charakterisieren die Relativposition des Beugungsgitters 32 zu dem Lichtbündel 34 bzw. zu "seiner optischen Achse. Das Beugungsgitter 32 ist ziemlich nahe an dem Fokus 42 oder auch demselben angeordnet, so dass nur relativ wenige Linien des als Beugungsgitter 32 dienenden Strichgitters die Bildung des Interferenzmusters bewirken. Dieses fällt auf die Elemente 43 bis 46 der Sensoranordnung. Dabei ist der das Interferenzmuster enthaltende Lichtbalken 46 vorzugsweise kürzer als die Sensoranordnung 33, so dass die außenständigen Sensorzellen 43, 46 nur von dem überlagerten Lichtfleck 46 nur noch teilweise überdeckt werden.The light reflected by the diffraction grating 32 or transmitted as in the example shown forms an interference light bundle 34a which contains diffracted and undiffracted components which impinge on the sensor arrangement 33 as interfering light beams. As illustrated for example in FIG. 6, this is preferably subdivided into a plurality, for example into four elements 43, 44, 45, 46, which together form an optoelectric converter (the sensor arrangement 33). The individual elements 43 to 46 of the sensor arrangement 33 are struck by an interference pattern which arises in the part of the interference light bundle 34a which has passed through the diffraction grating. As indicated in FIG. 5, there is a first brightness maximum parallel to the optical axis, which represents an undeflected beam component. On the right and left (in FIG. 5 above and below) of the undeflected beam there is a + 1st maximum and a - 1st maximum. The light bar (bar-shaped light spot) 44 shown on the left in FIG. 5, which is generated by the laser diode 35 and the objective 36, is thus fanned out by diffraction. The fanned out light spot, which is created by superimposing the 0th maximum with the + 1st maximum and the - 1st maximum, is thus larger than the light bar 44. It contains a pattern of interference lines, which are indicated at 46 in FIG. They characterize the relative position of the diffraction grating 32 to the light bundle 34 or to "its optical axis. The diffraction grating 32 is arranged quite close to the focus 42 or also the same, so that only relatively few lines of the grating serving as the diffraction grating 32 cause the formation of the interference pattern. This falls on the elements 43 to 46 of the sensor arrangement. The light bar 46 containing the interference pattern is preferably shorter than the sensor arrangement 33, so that the external sensor cells 43, 46 are only partially covered by the superimposed light spot 46.
Jedes Element 43, 44, 45, 46 ist jeweils an einen Kanal eines Analogverstärkers 47 angeschlossen. Dazu sind entsprechende Eingänge 53, 54, 55, 56 vorgesehen, die paarweise (53 und 54; 55 und 56) einen Differenzeingang bilden. Entsprechend wird aus den an den Eingängen 53, 54 anstehenden Signalen ein erstes Ausgangssignal an einem Ausgang 61 erzeugt. Ein Ausgang 62 des Verstärkers 47 gibt das verstärkte Differenzsignal der Eingänge 55 und 56 ab. Aufgrund der Anordnung der Sensorzellen 43, 44, 45, 46 auf eine Weise, dass das Sensorzellenpaar 43, 44 gegen das Sensorzellenpaar 45, 46 um eine halbe Interferenzlinienbreite versetzt ist, stehen an den Ausgängen 61, 62 des Verstärkers 47 um 90° phasenversetzte sinusförmige Signale an. Die Signale der Ausgänge 61, 62 werden an Triggerstufen 63, 64 weitergegeben, die die Sinunssignale in Rechtecksignale umwandeln. Ein nachgeschalteter Vorwärts/Rückwärts-Zähler 65 enthält die getriggerten Sinus- und Kosinussignale und zählt diese. Durch den 90°- Phasenversatz zwischen dem Sinus- und dem Kosinussignal ist eine eindeutige Richtungsbestimmung möglich, so dass der Vorwärts/Rückwärts-Zähler 65 entsprechend der Bewegungsrichtung des Beugungsgitters 32 seinen Zählwert in- krementiert oder dekrementiert . Parallel zu den Triggerstufen 63, 64 sind Analog/Digital-Wandlerstufen 66, 67 geschaltet, die den aktuellen Signalwert der Ausgänge 61, 62 in Digitalwerte umsetzen. Die so erhaltenen Digitalwerte sind ein Kennzeichen für die aktuelle Helligkeitsdifferenz zwischen den Sensorzellen 43, 44 und entsprechend 45, 46. Mit dieser Information ist eine Interpolation der Winkelposition auf der Sinuskurve zwischen einem Maximum und einem Minimum der Helligkeit bzw. des Signalwerts möglich. Die Auflösung kann deshalb besser sein als die Gitterliniendichte des Beugungsgitters 32 vorgibt. Die Analog/Digital-Wandlerstufen 66 , 61 bilden mit einer angeschlossenen Auswerteschaltung 68 eine Analog-Auswerteschaltung zur Bestimmung des Winkels zwischen Helligkeitsmaximum und Helligkeitsminimum.Each element 43, 44, 45, 46 is connected to a channel of an analog amplifier 47. Corresponding inputs 53, 54, 55, 56 are provided for this purpose, which form a differential input in pairs (53 and 54; 55 and 56). Correspondingly, a first output signal is generated at an output 61 from the signals present at the inputs 53, 54. An output 62 of the amplifier 47 outputs the amplified differential signal of the inputs 55 and 56. Due to the arrangement of the sensor cells 43, 44, 45, 46 in such a way that the pair of sensor cells 43, 44 is offset by half the interference line width from the pair of sensor cells 45, 46, there are sinusoidal out-of-phase at the outputs 61, 62 of the amplifier 47 Signals on. The signals of the outputs 61, 62 are passed on to trigger stages 63, 64, which convert the sin signals into rectangular signals. A downstream up / down counter 65 contains the triggered sine and cosine signals and counts them. The 90 ° phase offset between the sine and the cosine signal makes it possible to determine the direction clearly, so that the up / down counter 65 increments or decrements its count value in accordance with the direction of movement of the diffraction grating 32. Analog / digital converter stages 66, 67 are connected in parallel with the trigger stages 63, 64 and convert the current signal value of the outputs 61, 62 into digital values. The digital values obtained in this way are indicative of the current difference in brightness between the sensor cells 43, 44 and correspondingly 45, 46. With this information, an interpolation of the angular position on the sine curve between a maximum and a minimum of the brightness or the signal value is possible. The resolution can therefore be better than the grating line density of the diffraction grating 32 specifies. The analog / digital converter stages 66, 61, together with a connected evaluation circuit 68, form an analog evaluation circuit for determining the angle between the maximum brightness and the minimum brightness.
Die Ausgänge des Vorwärts/Rückwärts-Zählers 65 und die an die Analog/Digital-Wandler 67, 66 angeschlossenen Auswerteschaltung 68 sind mit einer Kombinierstufe 69 verbunden, die die von der Vorwärts/Rückwärts-Zählstufe 65 vorgegebenen Schrittzahlen und den von der Auswerteschaltung 68 abgegebenen Zwischenschrittwert addiert, um einen Messwert zu erhalten. Dieser wird an einem Ausgang 70 ausgegeben.The outputs of the up / down counter 65 and the evaluation circuit 68 connected to the analog / digital converters 67, 66 are connected to a combining stage 69 which contains the number of steps specified by the up / down counter stage 65 and the output from the evaluation circuit 68 Intermediate step value added to get a measured value. This is output at an output 70.
Die insoweit beschriebene Messeinrichtung 1 arbeitet wie folgt:The measuring device 1 described so far operates as follows:
Soll mittels der Messeinrichtung die Oberfläche 2 vermessen werden, wird der Tastarm 6 mit dem Tastelement 4 über die Oberfläche 2 des Werkstücks 3 geführt. Dazu wird bspw. bei der Messeinrichtung nach Figur 1 die Stelleinrichtung 16 betätigt. Das Tastelement 4 folgt dabei der Kontur und der Rauheit der Oberfläche 2, wodurch der Tast- arm 6 entsprechend ausgelenkt wird. Die Bewegung des Tastarms 6 überträgt sich auf das Beugungsgitter 32, das entsprechend der Auslenkung des Tastelements 4 bewegt wird. Damit wird das Beugungsgitter 32 relativ zu dem Lichtbündel 34 bzw. seiner optischen Achse verschoben. Entsprechend laufen die Interferenzlinien des Lichtflecks 46 über die Sensoranordnung 33. Jede Interferenzlinie erzeugt dabei eine Sinuswelle an den Ausgängen 31, 32. Der Zählinhalt des Vorwärts/Rückwärts-Zählers 65 gibt richtungsabhängig die Anzahl der durchgelaufenen Interf renzlinien wieder. Die Zwischenwerte werden mit der Auswerteschaltung 68 bestimmt. Die Kombinierstufe 69 gibt dadurch an ihrem Ausgang ein Positionssignal aus, dass die aktuelle Auslenkung des Tastelements 4 präzises kennzeichnet.If the surface 2 is to be measured by means of the measuring device, the probe arm 6 is guided with the probe element 4 over the surface 2 of the workpiece 3. For this purpose, the setting device 16 is actuated, for example, in the measuring device according to FIG. The feeler element 4 follows the contour and the roughness of the surface 2, whereby the feeler arm 6 is deflected accordingly. The movement of the probe arm 6 is transmitted to the diffraction grating 32, which is moved in accordance with the deflection of the probe element 4. The diffraction grating 32 is thus displaced relative to the light bundle 34 or its optical axis. Correspondingly, the interference lines of the light spot 46 pass through the sensor arrangement 33. Each interference line generates a sine wave at the outputs 31, 32. The counting content of the up / down counter 65 reflects the number of the interference lines passed, depending on the direction. The intermediate values are determined with the evaluation circuit 68. The combiner 69 thus outputs a position signal at its output that precisely identifies the current deflection of the sensing element 4.
Der veranschaulichte interferenzoptische Sensor kann nicht nur für eindimensionale Messaufgaben, sondern bedarfsweise auch für zweidimensionale Messaufgaben genutzt werden. Dazu werden zur Erzeugung des Interferenzbilds bspw. anstelle eines Strichgitters, zwei um 90° gegeneinander verdrehte Strichgitter verwendet, die entweder unabhängig voneinander oder gemeinsam bewegbar sind. In einigen Fällen kann auch ein Punktgitter (Raster) zur Anwendung kommen. Das Punktgitter kann durch kreisförmige oder anderweitig geformte Punkte auf lichtdurchlässigem oder lichtreflektierendem Untergrund gebildet sein. Auch die inverse Anordnung, bei der die Punkte durchsichtig oder reflektierend und die übrige Fläche undurchsichtig bzw. nichtreflektierend ausgebildet ist, ist anwendbar. Sensor- seitig wird dann nicht mit einem linienhaften Sensor gearbeitet, wie er in Figur 6 angedeutet ist, sondern mit einem Flächensensor oder mit zwei kreuzweise angeordneten Liniensensoren, die miteinander bspw. einen Winkel von 90° einschließen. Eine interferenzoptische Messeinrichtung zur Erfassung und Verfolgung der Bewegung eines mechanischen Elements 4 weist eine Lichtquelle 31 zur Abgabe eines interferenzfähigen Lichtbündels sowie ein Beugungsgitter und eine Sensoranordnung 33 auf. Von der Lichtquelle führt ein Strahlengang über das Beugungsgitter 32 zu der Sensoranordnung 33. Das Beugungsgitter zerlegt das Lichtbündel in mindestens drei Teilkomponenten, so dass auf der optischen Sensoranordnung 33 ein Lichtfleck mit drei einander überlappenden Maxima, dem mittleren nullten Maximum und dem beidseits davon liegenden minus ersten und plus ersten Maximum entsteht. Die Lichtstrahlen zur Erzeugung der drei Helligkeitsmaxima interferieren miteinander, so dass der resultierende überlagerte Leuchtfleck 46 Interferenzlinien enthält, die in einer oder anderen Richtung laufen, wenn das Beugungsgitter bewegt wird. Die Bewegung der Interferenzlinien wird mit der Sensoranordnung 33 erfasst und in einer Auswerteschaltung ausgewertet. Damit ist die präzise Erfassung jeder Bewegung des Beugungsgitters 32 möglich. Mit der vorgestellten Anordnung wird nahezu das gesamte von der Lichtquelle ausgesendete Licht zu erzeugendes Interferenzbilds ausgenutzt. Es entstehen somit lichtstarke Interferenzbilder schon bei geringen Lichtleistungen der Lichtquelle 31. Es können deshalb Bauelemente geringer Leistung zum Einsatz kommen. The illustrated optical interference sensor can not only be used for one-dimensional measurement tasks, but also, if necessary, for two-dimensional measurement tasks. For this purpose, for example, instead of a line grating, two line grids rotated by 90 ° with respect to one another are used to generate the interference image and can be moved either independently of one another or together. In some cases, a point grid (grid) can also be used. The point grid can be formed by circular or otherwise shaped points on a translucent or light-reflecting surface. The inverse arrangement, in which the points are transparent or reflective and the remaining surface is opaque or non-reflective, can also be used. On the sensor side, it is then not a linear sensor as indicated in FIG. 6 that is used, but rather an area sensor or two crosswise arranged line sensors which, for example, enclose an angle of 90 ° with one another. An optical interference measuring device for detecting and tracking the movement of a mechanical element 4 has a light source 31 for emitting a light beam capable of interference, as well as a diffraction grating and a sensor arrangement 33. A beam path leads from the light source via the diffraction grating 32 to the sensor arrangement 33. The diffraction grating divides the light bundle into at least three sub-components, so that on the optical sensor arrangement 33 a light spot with three overlapping maxima, the mean zero maximum and the minus lying on both sides thereof first and plus first maximum arises. The light beams for generating the three brightness maxima interfere with one another, so that the resulting superimposed light spot contains 46 interference lines that run in one direction or another when the diffraction grating is moved. The movement of the interference lines is detected by the sensor arrangement 33 and evaluated in an evaluation circuit. This enables the precise detection of every movement of the diffraction grating 32. With the arrangement presented, almost all of the interference image to be generated by the light source is used. Bright interference images thus arise even at low light outputs of the light source 31. Components of low output can therefore be used.

Claims

Patentansprüche : Claims:
1. Messeinrichtung (1), insbesondere zur Messung der Oberflächenrauheit und/oder der Oberflächenkontur eines Werkstücks (3) ,1. Measuring device (1), in particular for measuring the surface roughness and / or the surface contour of a workpiece (3),
mit einem Tastelement (4), das beweglich gelagert und mit der Werkstückoberfläche (2) in Anlage überführbar ist,with a probe element (4) which is movably supported and can be brought into contact with the workpiece surface (2),
mit einem Beugungsgitter (32) , das beweglich gelagert und mit dem Tastelement (4) verbunden ist,with a diffraction grating (32) which is movably mounted and connected to the probe element (4),
mit einer Lichtquelle (31) zur Erzeugung eines interferenzfähigen Lichtbündels (34) , das auf das Beugungsgitter (32) gerichtet ist, um ein Interferenzlichtbündel (34a) mit wenigstens einem Nullten (0.), einem positiven ersten (+1.) und einem negativem ersten Maximum (-1.) zu erzeugen,with a light source (31) for generating an interference-capable light bundle (34), which is directed onto the diffraction grating (32), around an interference light bundle (34a) with at least one zeroth (0.), one positive first (+1.) and one negative first maximum (-1.)
mit einer optischen Sensoranordnung (33), die dem von dem Beugungsgitter (32) kommenden Interferenzlichtbündel (34a) ausgesetzt ist.with an optical sensor arrangement (33) which is exposed to the interference light beam (34a) coming from the diffraction grating (32).
2. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die optische Sensoranordnung (33) mit einer digitalen Auswerteeinrichtung (63, 64, 65) verbunden ist, die wenigstens einen Zähler (65) zur Erfassung der Zahl an der Sensoranordnung (33) vorbeigezogener Interferenzstreifen aufweist.2. Measuring device according to claim 1, characterized in that the optical sensor arrangement (33) is connected to a digital evaluation device (63, 64, 65) which has at least one counter (65) for detecting the number of interference strips drawn past the sensor arrangement (33) having.
3. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Sensoranordnung (33) an eine Analσg- auswerteeinrichtung (66, 67, 68) angeschlossen ist, die eine Interpolationseinrichtung bildet, die dazu eingerich- tet ist, der von der Sensoranordnung (33) erfassten Helligkeit einen Positionswert zuzuordnen.3. Measuring device according to claim 1, characterized in that the sensor arrangement (33) is connected to an analσg evaluation device (66, 67, 68) which forms an interpolation device which is set up for this purpose. tet is to assign a position value to the brightness detected by the sensor arrangement (33).
4. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Sensoranordnung (33) wenigstens zwei Sensorelemente (43, 44, 45, 46) aufweist, die zur Erfassung der Helligkeiten an unterschiedlichen Stellen des Interferenzlichtbündels dienen.4. Measuring device according to claim 1, characterized in that the sensor arrangement (33) has at least two sensor elements (43, 44, 45, 46) which are used to detect the brightness at different points of the interference light beam.
5. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass zu der Sensoranordnung (33) zwei jeweils wenigstens einen Sensor (43, 44; 45, 46) enthaltende Sensorgruppen (43, 44; 45, 46) gehören, die gegeneinander um eine halbe Interferenzstreifenbreite versetzt angeordnet sind.5. Measuring device according to claim 1, characterized in that the sensor arrangement (33) includes two sensor groups (43, 44; 45, 46) each containing at least one sensor (43, 44; 45, 46), which are offset by half an interference fringe width are staggered.
6. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass das Tastelement (4) eindimensional beweglich gelagert ist.6. Measuring device according to claim 1, characterized in that the probe element (4) is movably supported in one dimension.
7. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass das Beugungsgitter (32) ein lichtdurchlässiges Gitter ist.7. Measuring device according to claim 1, characterized in that the diffraction grating (32) is a translucent grating.
8. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass das Beugungsgitter (32) quer zu dem Lichtbündel (34) beweglich gelagert ist.8. Measuring device according to claim 1, characterized in that the diffraction grating (32) is movably mounted transversely to the light beam (34).
9. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass sie eine Positionierungseinrichtung (16) enthält, die dazu eingerichtet ist, das Tastelement (4) in einer vorgegebenen Richtung über die Oberfläche des Werkstücks zu bewegen.9. Measuring device according to claim 1, characterized in that it contains a positioning device (16) which is set up to move the probe element (4) in a predetermined direction over the surface of the workpiece.
- 1$ - $ 1
10. Messeinrichtung nach Anspruch 1, dadurch gekennzeichnet, dass sie eine Krafterzeugungseinrichtung (18) zur Erzeugung einer Messkraft aufweist. 10. Measuring device according to claim 1, characterized in that it has a force generating device (18) for generating a measuring force.
EP01943100A 2000-05-23 2001-05-18 Probe with a diffraction grating for +1, 0 and -1 orders Withdrawn EP1287314A1 (en)

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DE10025461A DE10025461A1 (en) 2000-05-23 2000-05-23 Measurement device, especially for measuring workpiece surface roughness and/or contour has probe with diffraction grating for +1, 0 and -1 orders
DE10025461 2000-05-23
PCT/DE2001/001871 WO2001090698A1 (en) 2000-05-23 2001-05-18 Probe with a diffraction grating for +1, 0 and -1 orders

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Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4062008B2 (en) 2002-08-07 2008-03-19 株式会社東京精密 Digital measuring head
DE10349946B4 (en) * 2003-10-24 2008-04-17 Werth Messtechnik Gmbh Arrangement for measuring surface properties
DE102005007002B4 (en) * 2005-02-16 2006-12-28 Carl Mahr Holding Gmbh Roughness measuring device with exchangeable probe arm
JP5823306B2 (en) * 2011-03-18 2015-11-25 株式会社ミツトヨ Calibration method of surface texture measuring machine
US8701301B2 (en) 2011-04-19 2014-04-22 Mitutoyo Corporation Surface texture measuring instrument
DE102013012443A1 (en) * 2013-07-29 2015-01-29 Sikora Ag Method and device for measuring the centricity of a conductor in an insulating sheath

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3726595A (en) * 1970-01-07 1973-04-10 Canon Kk Method for optical detection and/or measurement of movement of a diffraction grating
US5871391A (en) * 1980-03-27 1999-02-16 Sensor Adaptive Machine Inc. Apparatus for determining dimensions
DE3071858D1 (en) * 1980-07-31 1987-01-22 Ibm Method and device for optical distance measurement
NL8005259A (en) * 1980-09-22 1982-04-16 Philips Nv DEVICE FOR MEASURING THE SURFACE OF AN OBJECT.
EP0242407A2 (en) * 1986-03-26 1987-10-28 Hommelwerke GmbH Device for measuring small lengths
DE8916050U1 (en) * 1989-03-14 1993-03-11 Dr. Johannes Heidenhain Gmbh, 8225 Traunreut, De
US5021649A (en) * 1989-03-28 1991-06-04 Canon Kabushiki Kaisha Relief diffraction grating encoder
GB2256476B (en) * 1991-05-30 1995-09-27 Rank Taylor Hobson Ltd Positional measurement
JP3495783B2 (en) * 1994-05-13 2004-02-09 キヤノン株式会社 Encoder
DE19652563A1 (en) * 1996-12-17 1998-06-18 Heidenhain Gmbh Dr Johannes Photoelectric position measuring device
DE19712622C5 (en) * 1997-03-26 2010-07-15 Dr. Johannes Heidenhain Gmbh Arrangement and method for the automatic correction of erroneous scanning signals of incremental position measuring devices

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0190698A1 *

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