WO2005062102A1 - Dispositif pour l'exploration optique confocale d'un objet - Google Patents

Dispositif pour l'exploration optique confocale d'un objet Download PDF

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Publication number
WO2005062102A1
WO2005062102A1 PCT/DE2004/002354 DE2004002354W WO2005062102A1 WO 2005062102 A1 WO2005062102 A1 WO 2005062102A1 DE 2004002354 W DE2004002354 W DE 2004002354W WO 2005062102 A1 WO2005062102 A1 WO 2005062102A1
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WO
WIPO (PCT)
Prior art keywords
mirror
optical
plane
focus
optical beam
Prior art date
Application number
PCT/DE2004/002354
Other languages
German (de)
English (en)
Inventor
Joachim Janes
Ulrich Hofmann
Original Assignee
Fraunhofer-Gesellschaft Zur Förderung Der Angewandten Forschung
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
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Application filed by Fraunhofer-Gesellschaft Zur Förderung Der Angewandten Forschung filed Critical Fraunhofer-Gesellschaft Zur Förderung Der Angewandten Forschung
Publication of WO2005062102A1 publication Critical patent/WO2005062102A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/0004—Microscopes specially adapted for specific applications
    • G02B21/002—Scanning microscopes

Definitions

  • the invention relates to a device for confocal optical scanning of an object, with an optical device for generating a first focus or an area with a small beam cross section of an injected optical beam in a first plane, a first mirror with a central aperture for the passage of the optical Beam from a back of the first mirror and a second mirror, which is arranged opposite the first mirror so that the optical beam passing through the aperture of the first mirror from the back is reflected on the first mirror.
  • Devices for confocal optical scanning of objects can be used in many technical fields in which an almost point-like scanning scanning of a surface is required.
  • Examples of this are bar code readers, scanning displays, detection devices for fingerprints or also confocal imaging, for example in confocal microscopy.
  • focusing an optical beam on the opening of a pinhole causes an approximately punctiform light source, which is mapped onto the object surface via an optical system.
  • the beam reflected from the object surface is in turn imaged on a pinhole, behind which the light passing through the pinhole can be detected. Only points on the surface of the object that are confocal with the punctiform light source and the detector-side pinhole contribute significantly to the detected light.
  • the resolution of the system is thus determined via the size of the pinhole opening. A larger area of the object surface can be scanned by scanning movement of the optical beam striking the object or by moving the object in the beam.
  • a device for confocal optical scanning of an object is described, for example, in US Pat. No. 6,172,789 B1.
  • This device comprises an optical waveguide from which the optical beam emerges and from the rear through a central aperture of a first
  • Plane mirror passes through.
  • the exit surface of the optical waveguide fiber represents an approximately punctiform light source.
  • the light beam strikes a second plane mirror arranged opposite the first mirror, through which it is reflected on the first mirror.
  • the light beam reflected by the first mirror is focused on an object surface to be examined via a lens.
  • the first mirror can be tilted about one or two axes, so that a larger object area can be scanned with the light beam by controlled tilting of this mirror.
  • the beam path of a portion of the reflection from the object surface tated light corresponds identically to the beam path of the incident optical beam, so that this reflected light beam re-enters the optical fiber.
  • the intensity of this reflected light beam can then be detected by a detector using a glass fiber switch.
  • a tiltable mirror with a central aperture is complex in terms of production technology, in particular if this mirror is a micromirror. Furthermore, reflections can occur on the focusing lens in front of the object, which can interfere with the detection of the radiation reflected from the object.
  • An optical transmission system is known from DE 195 03 675 C2, in which a laser beam is coupled into an optical fiber.
  • the laser beam passes through a central opening in a fixed concave mirror and strikes a rotatable plane mirror, which reflects it onto the concave mirror in such a way that the laser beam is focused at a desired angle on the entry surface of the optical waveguide.
  • the object of the present invention is to provide a device for confocal optical scanning of an object, which is simple to manufacture and can be used both for scanning illumination or illumination of an object and for detecting the light reflected on the object surface. DESCRIPTION OF THE INVENTION The object is achieved with the device according to claim 1. Advantageous embodiments of the device can be found in the following description and the exemplary embodiment.
  • the present device for confocal optical scanning of an object comprises an optical device for generating a first focus or an area of small beam cross section of an injected optical beam in a first plane, a first mirror with a central aperture for the passage of the optical beam from a rear side of the first Mirror, a second mirror which is arranged opposite the first mirror in such a way that the optical beam passing through the aperture of the first mirror from the rear is reflected on the first mirror, the second mirror being a mirror which can be tilted about at least one axis, by tilting it over the reflection on the first mirror, an area of an object plane can be scanned with the optical beam.
  • the first mirror is designed as a concave mirror and the optical device and the concave mirror can be coordinated with one another in such a way that the optical beam, after reflection on the concave mirror, forms a second focus confocal to the first focus or the area of the small beam cross section in the object plane.
  • an area of small beam cross section is to be understood as a beam cross section which, comparable to a focus, can be viewed as an approximately point-shaped light source.
  • objects can be scanned point-by-point in the object plane due to the confocal structure.
  • the beam returning on the identical beam path and reflected from the object surface can be detected, so that a scanning image of the surface is obtained, for example for the area of confocal microscopy.
  • the through opening or aperture in the concave mirror can be produced more easily than an aperture in a tiltable micromirror.
  • the optical device is composed of an adjustable condenser optical system, in which the coupled optical beam, which can also be brought in by an optical fiber, is focused on the first level via at least one first condenser lens and then with at least one second condenser lens is shaped so that the second focus lies in the object plane in coordination with the concave mirror.
  • a pinhole is arranged in the first level and blocks light radiation propagating outside the first focus. Through this first focus in connection with the pinhole, the optical device thus at least becomes one approximately point-shaped light source is provided, which is confocal to the second focus in the object plane.
  • the optical device comprises an optical fiber with an upstream condenser lens.
  • the optical beam coupled into the optical fiber emerges from the output surface of the optical fiber, which, due to the small cross section of the output surface, represents an approximately point-shaped light source.
  • the emerging optical beam is shaped in coordination with the concave mirror so that the second focus forms in the object plane.
  • the output surface of the optical fiber is confocal on the first level to the second focus.
  • Different light sources can be used to generate the optical beam, which allow beam shaping with appropriate optics.
  • the tiltable second mirror is preferably a micromirror manufactured using microsystems technology, so that the scannable surface of the object is only insignificantly shadowed by this mirror.
  • the structure, the production and the mode of operation of such a micromirror are known to the person skilled in the art and can be found, for example, in DE 19941363, the disclosure content of which with respect to this micromirror is part of the present patent application.
  • a parabolic mirror is preferably used for concave mirrors.
  • the optical device To use the present device for detecting the radiation reflected from the object surface, the optical device must have means for separating the returning reflected radiation from the coupled radiation. In one embodiment of the present invention, this is done with the aid of a beam splitter in the beam path of the injected optical beam before it enters the condenser optics.
  • a beam splitter cube When using a polarizing beam splitter cube, by using a polarization filter in front of the detector, the one returning can be deflected by the beam splitter cube
  • the optical device comprises an optical waveguide
  • the separation or splitting between the injected and the returning beam can be achieved via a fiber optic coupler.
  • a scanning image of the object surface can be generated by recording the intensity of the returning light beam as a function of the angular positions of the tilting axes of the tiltable mirror.
  • the angular positions of the tiltable mirror can easily be converted into Cartesian coordinates of the image plane.
  • the present device can be used in all technical fields in which a point-by-point scanning of an object surface using an optical beam is required. This applies both to lighting tasks, for example in the case of scanning displays, and to the area of imaging or examining the object surface by detecting the reflected light, such as, for example, in confocal microscopy.
  • the device can also be used to scan self-illuminating objects or objects illuminated by other light sources, in which case no optical beam is coupled in, but only the proportion of light emanating from the object is recorded as a function of the tilt angles.
  • Figure 1 shows a first example of a structure of the present device in a schematic representation.
  • Fig. 2 shows a second example of a structure of the present device in a schematic representation.
  • the device is composed of the optical device 6, the concave mirror 10 with the central through opening 11 and the micromirror 12 which can be tilted in two mutually perpendicular axes.
  • the light beam 1, which is coupled into the optical device 6, can be generated by a laser light source 15.
  • the optical device 6 is composed of a beam splitter cube 2, a first condenser lens 3, a second condenser lens 4 and the pinhole 5 in the first plane 30.
  • the beam splitter cube 2 is used to couple the light beam reflected by the object to a detector 9, which detects the intensity of this light beam as a function of the position of the micromirror 12.
  • the light beam 1 coupled into the device first strikes the beam splitter cube 2, from which it is split into a reflected beam (not shown) and a transmitted beam.
  • the reflected beam is irrelevant to the function of the present device.
  • the lens system consisting of the first condenser lens 3 and the second condenser lens 4
  • the light beam 1 is processed in such a way that on the one hand it has a first focal point 13 in the opening of the perforated diaphragm 5 in the first plane 30 and on the other hand the second one generated via the concave mirror 10 Focus 14 lies exactly in the object plane 20.
  • the two lenses 3, 4 of the optical device 6 serve primarily for beam shaping and can be adjusted in particular with regard to their distance and the distance to the concave mirror 10.
  • the beam emerging from the optical device 6 passes through the aperture 11 in the concave mirror 10 and strikes the micromirror 12 movable in two axes, as is known, for example, from the aforementioned DE 19941363.
  • micromirrors are used.
  • the advantage of a micromirror that can be tilted in two axes is that it can be used to scan an area in the object plane 20 without significantly reducing the size of this area by shading.
  • the beam incident through the aperture 11 is deflected by the tiltable micromirror 12 onto the reflecting surface of the concave mirror 10, which is preferably designed as a parabolic mirror. Instead of a parabolic mirror, a spherical mirror can also be used, for example.
  • the combination of the second condenser lens 4 and the concave mirror 10 with a suitable focal length defines a focal plane which is also the image or object plane 20 in which the object surface to be examined lies.
  • the detection light passes through the beam splitter cube 2 and is reflected downwards by the latter in the present example in FIG. 1 onto a detector 9, which detects the intensity of the reflected beam. This intensity is proportional to the intensity reflected by the object surface and is recorded as a function of the tilt angle of the two axes of the tiltable mirror 12.
  • This intensity as a function of the tilt angle of the two axes of the tiltable mirror 12 can be represented as an image using suitable software.
  • a polarizing beam splitter cube 2 is used. Provided that the injected laser light is linearly polarized (direction of polarization perpendicular to the plane of the drawing in FIG. 1), in the detection direction at the exit of the
  • a corresponding linear polarization filter can be used in front of the detector 9 in the beam splitter cube 2.
  • the detection intensity is reduced by a little more than a factor of 2, but at the same time all scattering intensities of the linearly polarized laser light are noticeably reduced.
  • all optical surfaces of the present device can be anti-reflective for the corresponding wavelength of the laser light.
  • one can also be made of optical fibers Use the optical device 6 formed according to FIG. 2.
  • the light from the laser light source 15 is coupled into the optical waveguide 7.
  • a condenser lens 4 is used at its output, which adjusts the output characteristic of the laser light from the optical fiber or the coupling characteristic of the detection light into the fiber. Due to its small cross-section, the output surface of the optical waveguide 7 lying in the plane 30 represents an approximately punctiform light source comparable to the focus 13 within the pinhole 5 of FIG. 1.
  • the further beam path is identical to that of the device of FIG. 1.
  • the lens 4 and the concave mirror 10 is matched to one another in order to generate the focus 14 in the image or object plane 20.
  • a fiber-optic coupler 8 can be used for coupling out the returning detection light into the detector 9, as illustrated in FIG. 2.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Microscoopes, Condenser (AREA)

Abstract

L'invention concerne un dispositif servant à l'exploration optique confocale d'un objet et comprenant un dispositif optique (6) servant à générer un premier foyer (13) d'un rayon optique injecté (1) dans un premier plan (30), un premier miroir (10) à ouverture centrale (11) pour le passage du rayon optique (1) à partir d'une face arrière du premier miroir (10), ainsi qu'un deuxième miroir (12) placé par rapport au premier miroir (10) de sorte que le rayon optique (1) traversant l'ouverture (11) du premier miroir (10) par la face arrière est réfléchi sur le premier miroir (10). Le dispositif selon l'invention est caractérisé en ce que le premier miroir est un miroir concave (10) et en ce que le deuxième miroir (12) est un miroir basculant autour d'au moins un axe, dont le basculement permet d'explorer une zone d'un plan d'objet (20) au moyen du rayon optique (1). En outre, le dispositif optique (6) et le miroir concave (10) sont accordés l'un par rapport à l'autre de sorte que le rayon optique (1) forme, après réflexion sur le miroir concave (10), un deuxième foyer (14) dans le plan d'objet (20), ce deuxième foyer (14) étant confocal au premier foyer (13). Le dispositif selon l'invention peut être produit aisément et peut être utilisé aussi bien pour l'éclairage point par point par balayage d'un objet que pour l'exploration point par point par balayage de l'objet.
PCT/DE2004/002354 2003-12-19 2004-10-22 Dispositif pour l'exploration optique confocale d'un objet WO2005062102A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2003159853 DE10359853B3 (de) 2003-12-19 2003-12-19 Vorrichtung zum konfokalen optischen Abtasten eines Objekts
DE10359853.7 2003-12-19

Publications (1)

Publication Number Publication Date
WO2005062102A1 true WO2005062102A1 (fr) 2005-07-07

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WO (1) WO2005062102A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108917929A (zh) * 2018-05-24 2018-11-30 中国科学院上海微系统与信息技术研究所 太赫兹共焦显微成像系统及其成像方法

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3752998A (en) * 1972-09-01 1973-08-14 Us Army Linear scanning seeker with single axis rotation
GB2256937A (en) * 1991-06-21 1992-12-23 Gec Ferranti Defence Syst Optical scanner
DE19503675A1 (de) * 1994-02-22 1995-08-24 Mitsubishi Electric Corp Optisches Übertragungssystem und Verfahren zur Lichtausstrahlung
US5546214A (en) * 1995-09-13 1996-08-13 Reliant Technologies, Inc. Method and apparatus for treating a surface with a scanning laser beam having an improved intensity cross-section
US5640270A (en) * 1996-03-11 1997-06-17 Wyko Corporation Orthogonal-scanning microscope objective for vertical-scanning and phase-shifting interferometry
WO2001001184A1 (fr) * 1999-06-25 2001-01-04 Gim Systems Ltd. Microscope a balayage par affichage lcd
US6172789B1 (en) * 1999-01-14 2001-01-09 The Board Of Trustees Of The Leland Stanford Junior University Light scanning device and confocal optical device using the same
DE19941363A1 (de) * 1999-08-31 2001-04-05 Fraunhofer Ges Forschung Mikroaktorbauteil und Verfahren zur Herstellung
US6545260B1 (en) * 1999-11-19 2003-04-08 Olympus Optical Co., Ltd. Light scanning optical device which acquires a high resolution two-dimensional image without employing a charge-coupled device

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3752998A (en) * 1972-09-01 1973-08-14 Us Army Linear scanning seeker with single axis rotation
GB2256937A (en) * 1991-06-21 1992-12-23 Gec Ferranti Defence Syst Optical scanner
DE19503675A1 (de) * 1994-02-22 1995-08-24 Mitsubishi Electric Corp Optisches Übertragungssystem und Verfahren zur Lichtausstrahlung
US5546214A (en) * 1995-09-13 1996-08-13 Reliant Technologies, Inc. Method and apparatus for treating a surface with a scanning laser beam having an improved intensity cross-section
US5640270A (en) * 1996-03-11 1997-06-17 Wyko Corporation Orthogonal-scanning microscope objective for vertical-scanning and phase-shifting interferometry
US6172789B1 (en) * 1999-01-14 2001-01-09 The Board Of Trustees Of The Leland Stanford Junior University Light scanning device and confocal optical device using the same
WO2001001184A1 (fr) * 1999-06-25 2001-01-04 Gim Systems Ltd. Microscope a balayage par affichage lcd
DE19941363A1 (de) * 1999-08-31 2001-04-05 Fraunhofer Ges Forschung Mikroaktorbauteil und Verfahren zur Herstellung
US6545260B1 (en) * 1999-11-19 2003-04-08 Olympus Optical Co., Ltd. Light scanning optical device which acquires a high resolution two-dimensional image without employing a charge-coupled device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108917929A (zh) * 2018-05-24 2018-11-30 中国科学院上海微系统与信息技术研究所 太赫兹共焦显微成像系统及其成像方法
CN108917929B (zh) * 2018-05-24 2024-04-19 中国科学院上海微系统与信息技术研究所 太赫兹共焦显微成像系统及其成像方法

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