EP1272811A1 - Dispositif de mesure interferometrique - Google Patents

Dispositif de mesure interferometrique

Info

Publication number
EP1272811A1
EP1272811A1 EP02740218A EP02740218A EP1272811A1 EP 1272811 A1 EP1272811 A1 EP 1272811A1 EP 02740218 A EP02740218 A EP 02740218A EP 02740218 A EP02740218 A EP 02740218A EP 1272811 A1 EP1272811 A1 EP 1272811A1
Authority
EP
European Patent Office
Prior art keywords
measuring device
radiation
path
light path
measurement
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Withdrawn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
EP02740218A
Other languages
German (de)
English (en)
Inventor
Michael Lindner
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch 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
Priority claimed from DE10123844A external-priority patent/DE10123844A1/de
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1272811A1 publication Critical patent/EP1272811A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/02062—Active error reduction, i.e. varying with time
    • G01B9/02064—Active error reduction, i.e. varying with time by particular adjustment of coherence gate, i.e. adjusting position of zero path difference in low coherence interferometry
    • G01B9/02065—Active error reduction, i.e. varying with time by particular adjustment of coherence gate, i.e. adjusting position of zero path difference in low coherence interferometry using a second interferometer before or after measuring interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02049—Interferometers characterised by particular mechanical design details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/02056—Passive reduction of errors
    • G01B9/02057—Passive reduction of errors by using common path configuration, i.e. reference and object path almost entirely overlapping
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/02075—Reduction or prevention of errors; Testing; Calibration of particular errors
    • G01B9/02076—Caused by motion
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/0209—Low-coherence interferometers

Definitions

  • the invention relates to an interferometric measuring device for measuring a surface or interface of a measurement object.
  • Such an interferometric measuring device is identified as known in DE 1 97 2 1 843 C1, this known interferometric measuring device being constructed as a white light interferometer measuring device with a section designed as a modulation interferometer and a section designed as an imaging interferometer that is assigned to the measurement object.
  • the imaging interferometer is designed in such a way that measurements can also be carried out in narrow cavities. It is suggested that a first 02/082007
  • a measuring probe can be inserted into cavities. E.g. in a manufacturing process during measurement, vibrations of the measuring device and / or the measurement object can result in inaccuracies in the measurement result.
  • a radiation generation unit for example a light-emitting diode or superluminescent diode, emits a short-coherent radiation, which is split via a beam splitter into a first partial beam guided via object light and a second partial beam guided via a reference path.
  • the reference light path is changed periodically by means of two deflector elements and a fixed diffraction grating arranged behind them by actuating the deflector elements in order to scan the object surface in the depth direction. If the object light path and the reference light path match, there is a maximum 02/082007
  • the interference contrast which is detected by means of an evaluation device connected downstream of the photodetector device.
  • the invention has the object of providing an interferometric measurement device of the type mentioned to provide, with the impact of '
  • connection unit is provided, by means of which at least one section of the measuring device associated with the measurement object can be directly mechanically rigidly and detachably connected to the measurement object.
  • Connection unit is a mechanical adaptation between the measurement object and the measuring device for the measurement process. Then the connection can be released and a mechanically rigid coupling to the subsequent measurement object can be made, e.g. carry out a quality control in a series production.
  • connection unit is formed by a plug, clamp, tension, snap, clip or screw connection.
  • An advantageous embodiment of the interferometric measuring device is that it is designed as a white light interferometer measuring device with an object light path and a reference light path and that at least the reflective reference plane can be connected to the measuring object by means of the connecting unit.
  • a compact structure is achieved in that the object light path and the reference light path form an interconnected rigid unit consisting of object arm and reference arm. 02/082007
  • the white light interferometer has a modulation interferometer and an imaging interferometer assigned to the object, this results in a simplified operation since the generally more complex modulation interferometer with the device for changing the light path is separated from the imaging interferometer assigned to the measurement object, which corresponds to this - can be constructed simply and robustly and can be adapted to the respective measuring task.
  • a structure advantageous for handling z. B characterized by a short-coherent radiation generating unit, a beam splitter for forming a first and a second partial beam, with the measurement changing the optical path length of the first partial beam relative to the optical path length of the second partial beam, the one formed by the beam splitter first partial beam is first directed to a fixed first mirror via a first arm, while the second partial beam is directed to the reflecting element via a second arm, the optical path difference between the first and second arms being greater than the coherence length of the radiation, wherein the radiation which comes from the first mirror 1 and the reflecting element and which is passed on together is guided by means of a further beam splitter partly via the object light path to the measurement object and partly via the reference path to a reference mirror, the reference mirror being in a s such a distance is arranged with respect to the measurement object that the path difference between the first mirror and the reflecting element is eliminated, and wherein the radiation incident on the reference mirror and that directed to the measurement object Radiation reflects superimposed and is recorded by
  • a construction which is favorable for handling consists in that the reference light path is formed in a separate reference office or in an optical probe through which the radiation guided to the measurement object is also guided, the reference mirror reflecting the part of the radiation belonging to the reference light path and that part of the object light path that transmits the radiation.
  • a simple measurement of different measuring surfaces is made possible by arranging at least one optical element and / or elements deforming the wavefront of the radiation in the object light path.
  • At least one intermediate image is generated in the object light path and in that both the radiation leading to the measurement object and the radiation returning from it run through the optical probe.
  • a favorable construction also results from the fact that the reference mirror is provided on a plane plate or a prism.
  • a fiber optic is arranged between the beam splitter and the further beam splitter.
  • FIG. 1 shows a first exemplary embodiment of an interferometric measuring device with a modulation interferometer and an imaging interferometer rigidly connected to an object, 02/082007
  • Fig. 2 shows another embodiment in which the imaging interferometer has a Commo ⁇ -Path structure and is rigidly connected to the object, and
  • Fig. 3 shows a further structure of the interferometric measuring device with a common reference and measuring light path (Cornmon Path
  • Fig. 1 shows an interferometric measuring device with a modulation interferometer MI removed from an object D to be measured and an imaging interferometer AI assigned to the object O.
  • the modulation interferometer MI has a short-coherent or broadband radiation-generating radiation unit SLD, such as a light-emitting diode or superluminescent diode, the radiation of which is divided by means of a beam splitter ST1 into a first partial beam T1 of a first arm and a second partial beam T2 of a second arm.
  • SLD short-coherent or broadband radiation-generating radiation unit
  • the setup corresponds to a Michelson interferometer.
  • the second partial beam T2 is reflected by a reference plane in the form of a reference mirror RSP1, the second arm periodically, for example, by moving the reference mirror RSP1 or by means of acousto-optical deflectors, as described in DE 1 97 21 842 C2 mentioned at the beginning will be changed. If the change in the light path s with two O 02/082007
  • the optical path difference between the arms thus formed is greater than the coherence length of the one generated by the radiation generation unit SLD
  • the reflected radiation is fed into the imaging interferometer via the beam splitter ST1, a fiber optic LF and a further beam splitter ST2.
  • An object light path with an optical probe OS and a reference light path with a further reference mirror RSP2 are formed in the imaging interferometer AI, which is likewise designed as a Michelson interferometer.
  • the radiation is coupled into the optical probe OS, so that the radiation is a surface of a measurement object to be measured
  • the object surface is imaged by the optical probe OS via one or more intermediate images, for example, on a photodetector device in the form of an image converter or image sensor BS, for example a CCD camera.
  • the image of the measurement object O on the image sensor BS is overlaid with the reference wave of the second partial beam of the reference light path.
  • high interference contrast occurs when a path difference in the reference light path and the measurement light path is smaller than the coherence length.
  • the measuring principle is based on white light interferometry (short-coherence interferometry), as described in more detail in the publications mentioned at the beginning.
  • the length of the reference light path is varied over the entire measuring range for scanning in the depth direction of the surface to be measured by moving the mirror RSP1 in the second arm of the modulation interferometer MI, the length of the reference light path at which the highest interference contrast occurs being detected for each measuring point ,
  • the intermediate images make it possible to image the surface of the measurement object with a high lateral resolution over a distance that is large compared to the diameter of the imaging optics.
  • the optical probe OS is similar to an endoscope or borescope, but the illumination and the return of the radiation coming from the measurement surface are carried out via the same optical arrangement via at least one intermediate image. In Fig. 1, some lenses L are shown schematically as further imaging elements. The actual intermediate images are generated in the optical probe OS.
  • the same optical probe can also be integrated into the reference path between the beam splitter ST2 and the reference mirror RSP2 as in the object path between the beam splitter ST2 and the measurement object O.
  • the interferometric measuring device can also be arranged with a common reference and measuring arm (common path 5 order).
  • the interferometric measuring device is again illuminated with a short-coherent (broadband) radiation generation unit.
  • the beam splitter ST1 divides the light into the first partial beam T1 and the second partial beam T2, the first partial beam T1 being fixed on the first mirror SP1 and the second partial beam T2 falling on the reflecting element RS P1 in the form 10 of the reference mirror.
  • the optical path difference between the arms thus formed is in turn greater than the coherence length of the radiation generated by the radiation generating unit SLD.
  • the reflected radiation is fed into the optical probe OS via the beam splitter ST1 and the further beam splitter ST2.
  • the peculiarity of this construction is that a reference mirror RSP2 is located in the object path or in the optical probe OS itself.
  • the reference mirror RSP2 can be applied on a flat plate or on a prism. By using a prism, the wavefront of the radiation illuminating the object surface, i.e. the object wave to the geometry
  • the measurement object O is in turn imaged on the image sensor BS by means of the optical probe OS and superimposed on the reference wave by means of one or more intermediate images.
  • the reflecting element RSP1 is moved over the measuring range or the change in the light 02/082007
  • the radiation from the beam splitter ST1 can also be transmitted to the further beam splitter ST1 by means of fiber optics LF, as shown in FIG. 2 shown.
  • fiber optics LF fiber optics LF
  • a free jet setup can be selected.
  • the imaging interferometer A is designed as a rigid mechanical unit, at least in the section of the object light path and the reference light path, which in turn is rigidly and detachably connected directly to the measurement object O during the measurement by means of a connection unit VE in a connection area VB ,
  • the connection unit is, for example, a screw connection with a union nut, a screw section of the imaging interferometer AI that can be screwed into a threaded bore of the measurement object O, a plug connection, a snap or clip 02/082007
  • the object light path or object arm and the reference light path or reference arm can be inserted together into the measurement object O.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

L'invention concerne un dispositif de mesure interférométrique pour la mesure d'une surface ou d'une surface limite d'un objet de mesure (O). L'invention vise à inhiber l'influence de secousses sur le résultat de mesure. A cet effet, une unité de raccordement (VE) sert à raccorder à l'objet de mesure (O), directement et de manière détachable et mécaniquement rigide, au moins une section du dispositif de mesure affectée à l'objet de mesure (O).
EP02740218A 2001-04-09 2002-03-16 Dispositif de mesure interferometrique Withdrawn EP1272811A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE10117658 2001-04-09
DE10117658 2001-04-09
DE10123844A DE10123844A1 (de) 2001-04-09 2001-05-16 Interferometrische Messvorrichtung
DE10123844 2001-05-16
PCT/DE2002/000967 WO2002082007A1 (fr) 2001-04-09 2002-03-16 Dispositif de mesure interferometrique

Publications (1)

Publication Number Publication Date
EP1272811A1 true EP1272811A1 (fr) 2003-01-08

Family

ID=26009047

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02740218A Withdrawn EP1272811A1 (fr) 2001-04-09 2002-03-16 Dispositif de mesure interferometrique

Country Status (3)

Country Link
EP (1) EP1272811A1 (fr)
JP (1) JP4373094B2 (fr)
WO (1) WO2002082007A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2810512C2 (de) * 1978-03-10 1980-03-27 Siemens Ag, 1000 Berlin Und 8000 Muenchen Ebenheitsmeßvorrichtung
US4541717A (en) * 1983-12-08 1985-09-17 Fuji Photo Optical Co., Ltd. Attraction holding device
DE4108944A1 (de) * 1991-03-19 1992-09-24 Haeusler Gerd Verfahren und einrichtung zur beruehrungslosen erfassung der oberflaechengestalt von diffus streuenden objekten
US5689337A (en) * 1996-08-15 1997-11-18 Wyko Corporation Coaxial disc-mount for measuring flatness of computer-drive discs by interferometry
DE19721842C2 (de) * 1997-05-26 1999-04-01 Bosch Gmbh Robert Interferometrische Meßvorrichtung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02082007A1 *

Also Published As

Publication number Publication date
JP4373094B2 (ja) 2009-11-25
JP2004518985A (ja) 2004-06-24
WO2002082007A1 (fr) 2002-10-17

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