WO2014184793A1 - Procédé et système destinés à être utilisés pour l'examen d'échantillons par la détection d'une émission excitée optiquement provenant de l'échantillon - Google Patents

Procédé et système destinés à être utilisés pour l'examen d'échantillons par la détection d'une émission excitée optiquement provenant de l'échantillon Download PDF

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Publication number
WO2014184793A1
WO2014184793A1 PCT/IL2014/050418 IL2014050418W WO2014184793A1 WO 2014184793 A1 WO2014184793 A1 WO 2014184793A1 IL 2014050418 W IL2014050418 W IL 2014050418W WO 2014184793 A1 WO2014184793 A1 WO 2014184793A1
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WO
WIPO (PCT)
Prior art keywords
light
sample
plane
reflected
illumination
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Application number
PCT/IL2014/050418
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English (en)
Inventor
Michael Elbaum
David KIRCHENBUECHLER
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Yeda Research And Development Co. Ltd.
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 Yeda Research And Development Co. Ltd. filed Critical Yeda Research And Development Co. Ltd.
Publication of WO2014184793A1 publication Critical patent/WO2014184793A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/06—Means for illuminating specimens
    • G02B21/08—Condensers
    • G02B21/10—Condensers affording dark-field illumination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/64—Fluorescence; Phosphorescence
    • G01N21/645—Specially adapted constructive features of fluorimeters
    • G01N21/6456—Spatial resolved fluorescence measurements; Imaging
    • G01N21/6458—Fluorescence microscopy
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/16—Microscopes adapted for ultraviolet illumination ; Fluorescence microscopes
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/36—Microscopes arranged for photographic purposes or projection purposes or digital imaging or video purposes including associated control and data processing arrangements
    • G02B21/365—Control or image processing arrangements for digital or video microscopes

Definitions

  • the present invention is in the field of optical inspection/measurement/imaging of a sample based on detection of emission from the sample, e.g. microscopy such as fluorescent or Raman microscopy, and relates to a method and system for separating (distinguishing) between illuminating (exciting) and emitted (excited) light in such an optical system.
  • microscopy such as fluorescent or Raman microscopy
  • Optical systems of the type utilizing detection of light emitted/excited in a specimen in response to illuminating/exciting light involve illumination of a specimen with one wavelength (color) of light, and acquisition of an image at a different wavelength (typically but not exclusively longer than that of the illumination).
  • the most common mode of operation is by wide-field epi-illumination, in which the illuminating light enters an objective from the same side on which the image is formed.
  • the required separation between light emitted from a sample ("signal" to be detected) and illuminating light returned from the sample (“stray” to be removed) is typically performed by spectral separation using a matched set of colored filters.
  • the filters include an excitation filter, a dichroic mirror for reflecting the short wavelength of illuminating light and passing the longer wavelength emission to a detector (or vice versa), and an emission filter in the detection path that further selects the emission colors and, importantly, blocks leakage of the illuminating color.
  • Light of the excitation wavelength is focused onto the specimen through the objective lens.
  • the fluorescence emitted by the specimen is focused onto the detector by the same objective that is used for the excitation.
  • Excitation light reflected from the specimen reaches the objective together with the emitted light.
  • the emission filter between the objective and the detector can filter out the excitation light from fluorescent light.
  • spectral separation based optical techniques The problem with the existing, spectral separation based optical techniques is associated inter alia with the fact that blocking powers of spectral filters (e.g. dichroic mirrors, emission filters) are often weaker than required. Moreover, the need to block effectively all the illuminating light while maximally collecting the emission severely limits simultaneous acquisition of multiple color signals. Considering fluorescence microscopy techniques with spectral separation, the image quality is dominated by the quality of the filters, as the emission intensity is normally orders of magnitude weaker than the illumination intensity. Even a simple back-reflection of the illumination from a sample may be much stronger than the emitted signal of interest. Any improvement in spectral separation is translated immediately into improved signal to noise ratio, enabling detection of weaker and/or more transient signals.
  • spectral filters e.g. dichroic mirrors, emission filters
  • the present invention provides a novel approach for use in optical inspection systems of the kind specified, i.e. systems where illuminating and emitted light are of different wavelengths and propagate along a common detection path.
  • the invention separation between illuminating and emitted radiations returned from a specimen is achieved utilizing spatial separation, which is used preferably alternatively, or possibly additionally, to spectral separation between them.
  • the invention is advantageously useful for inspecting specimens that are substantially reflective or transmitting with respect to illuminating light, rather than scattering.
  • the invention may be used in an optical system operating in transmission or reflective mode, or the so-called trans-illumination or epi-illumination system.
  • an objective lens unit is mounted such that its front focal plane substantially coincides with a sample plane, and the objective lens unit collects illuminating light and emitted light and directs both, possibly attenuated by spectral filters, along a common light detection path to a detector.
  • a spatial filter (beam stop or mask) is provided in the detection path and is placed substantially in a plane conjugate to a back focal plane of the objective lens unit.
  • the optical system suitable for using the invention preferably utilizes a small light source, such as a laser.
  • the optical system is configured such that illuminating light incident on a sample is collimated light.
  • a device of the invention in its simplest configuration includes a spatial filter defining a small light blocking region placed in or near the Fourier plane of the relay lens.
  • the illuminating light returns to a point, as it was focused to the objective back aperture/focal plane.
  • the light blocking region in the spatial filter has an appropriate dimension (for illumination by extended sources, the blocking region is appropriately larger) to cover the spot of light, and is aligned so as to overlap with it.
  • this is a negligible fraction of the system aperture for the image, meaning that the loss of emission light is very small.
  • the inventors have found that the use of such a device is extremely effective using laser illumination, to the extent that the emission filter may sometimes be removed entirely without deterioration in image signal to noise ratio.
  • Modern optical microscope design is based on two sets of conjugate planes: the conjugate sample planes, and the objective back-focal or "aperture" planes.
  • the objective forms an image of the sample at the primary image plane, either directly or in combination with a telan lens in so-called "infinity-focus” systems.
  • the eyepiece or camera sensor (detector) is placed at this image plane.
  • Geometric constraints, or the need to introduce additional magnification often require an optical relay to re -project the image to a more distant plane.
  • the lens that relays the image also relays the conjugate aperture plane.
  • it is found at a distance of one focal length Fr from the relay lens. It is often called the Fourier plane because the distribution of light there presents a Fourier transform of the image.
  • conjugate sample planes and aperture planes are arranged such that excitation/illuminating light is focused where excited/emitted light is parallel (collimate) or vice versa, and a spatial filter defining a small light blocking region is placed at or near the conjugate aperture plane, re -projected after the primary image plane, so as to block the excitation light with minimal effect on the emission.
  • the optical system utilizing the invention may provide a significant cost reduction, and moreover vastly enhanced flexibility in collection or spectroscopy on the emission colors.
  • the invention makes it possible to concurrently illuminate several fluorescent dyes with several excitation colors, where the excitation of one overlaps the emission of another. This is not possible with the spectral separation alone, and creates a demand for very complex "multi-band" filter/mirror combinations.
  • it may yet be possible to replace a wavelength-selective filter (dichroic mirror) by a simple partial mirror, if care is taken to minimize scattering of the illumination light.
  • an optical system for use in inspection of a sample by detecting optically excited emission from the sample comprising:
  • a lens arrangement defining an illumination path for directing illuminating light of a first wavelength range onto an illumination region on a sample plane and a collection path for directing reflected illuminating light of said first wavelength range and emitted light of a second wavelength range propagating from the sample plane towards a detection plane, said lens arrangement comprising a plurality of lenses configured for focusing the reflected illumination light onto a conjugate aperture plane and imaging the illumination region by the collected emitted light onto a conjugate sample plane corresponding to the detection plane, thereby spatially separating optical paths of the collected reflected illumination and emitted radiations in the vicinity of a focal location of the reflected light;
  • a spatial filter defining a light blocking region accommodated in the collection path in the conjugate aperture plane at a focal location of said reflected illumination light, thereby substantially preventing the illumination light from reaching the detection plane.
  • the spatial filter may be implemented as a mask in the form of a thin transparent (e.g. glass) plate with a small light blocking (opaque) region.
  • a thin transparent (e.g. glass) plate with a small light blocking (opaque) region.
  • a method for inspection of a sample by detecting optically excited emission from the sample comprising: illuminating a region on the sample with light in a first wavelength range to cause emission from the sample in a second wavelength range; collecting light reflected from the sample and light emitted by the sample propagating substantially along the same optical path and directing the collected light towards a detection plane and spatially separating between said reflected light and said emitted light in the vicinity of a focal location of the reflected light, thereby substantially spectrally separating between the reflected illuminating light and the emitted light at the detection plane.
  • Fig. 1 illustrates the design of a conventional wide-field epi-fluorescence microscope
  • Fig. 2 illustrates schematically an example of the configuration of and light propagation scheme in an optical system utilizing the invention
  • Fig. 3 illustrates schematically another example of the configuration of and light propagation scheme in an optical system utilizing the invention.
  • Fig. 1 shows the design scheme of a modern state of the art epi-fluorescence microscope, which requires multiple spectral filters for reducing illumination spectrum in the detected light.
  • FIG. 2 there is schematically illustrated an example of an optical system 10 utilizing the invention.
  • the optical system 10 is configured generally similar to that of an epi-illumination microscope. It should be understood that the principles of the invention are limited neither to microscopes nor to epi-illumination arrangements of optical systems. The principles of the invention may be used in any optical system where excited (emitted) light, of a wavelength different from exciting (illuminating) light, is to be effectively detected/observed.
  • the optical system 10 is associated with a light source unit 12 for directing illuminating (exciting / pumping) light Lm from the light source unit 12 towards a sample plane SP where a sample under inspection is located (typically on a stage or table, or any other support surface).
  • the optical system 10 includes an objective lens unit 14, and a lens system for directing light towards a detection plane.
  • the detection plane may be constituted by a light sensitive surface of an imager (camera), or an eyepiece for visual observation, as the case may be.
  • the light directing lens system includes an image-forming collection lens unit 18 (telan lens, one or more lenses) and possibly also a relay lens unit 20. Telan lens (or tube lens), generally at least one, forms an image at the camera plane in an "infinity corrected" optical system.
  • a wavelength-selective filter e.g. a dichroic mirror 16 in the optical path of illuminating light propagating towards the sample plane.
  • a dichroic mirror may be used for selecting a desired wavelength for illumination (exciting) so as to cause emission from the given sample.
  • the dichroic mirror might not be used at all, or may be replaced by a partially reflecting mirror in applications where a broadband light source is used without interference from the part of the spectrum that overlaps the emission wavelengths.
  • the epi-illumination configuration is used, in which case the objective lens is located close to the sample plane such that both the reflection of the illuminating light Lm and the emitted light L em on their way from the sample first pass through the objective 14 and then interact with the dichroic mirror 16. It should be understood that in case of trans-illumination configuration, the dichroic mirror 16 might not be used.
  • optical system 10 defines an illumination channel for directing illuminating light Lm from the light source unit 12 to the sample plane SP, and a light collection channel for collecting light propagating from the sample and appropriately directing at least part thereof towards the detection plane.
  • the light propagating from the sample along the detection channel includes light formed by reflected illuminating light Lm of one (first) wavelength range and light formed by emitted light L em of a different (second) wavelength range.
  • the illumination channel includes the objective lens unit 14, and possibly includes a focusing lens unit 15 associated with the light source unit, and further possibly includes the dichroic mirror 16.
  • the system 10 is preferably configured so as to provide wide-field illumination of the sample (e.g. by collimating the light Lm illuminating the sample).
  • the light collection channel is formed by lens units 18 and 20, and in the epi-illumination set up also by objective 14 and dichroic mirror 16.
  • the optical elements of the system are configured and arranged so as to define conjugate aperture planes CAPi and CAP 2 , and conjugate sample planes CSPi and CSP 2 .
  • the objective lens unit 14 is located such that its front focal plane substantially coincides with the sample plane SP.
  • Conjugate aperture plane CAPi is the back focal plane of the objective 14.
  • a spatial filter 22 designed as a beam stop with respect to sample's reflection of illuminating light, is positioned in the conjugate aperture plane at a focal location of illuminating light reflected from an illumination region IS.
  • the beam stop 22 is located in the aperture plane CAP 2 .
  • the spatial filter 22 defines a light blocking region (beam stop) having a dimension corresponding to that of the focal projection of the reflected illumination light in the respective plane.
  • light Lm from the light source 12 defining an illumination aperture is focused by lens 15 onto the back focal plane CAPi of the objective 14, and the so created collimated light L m is directed by objective 14 onto the illumination spot IS on the sample, thereby causing emission L em from the sample together with creating reflection of this light Lm from the sample.
  • the objective 14 collects these light portions and directs collimated beam of emitted light L em and focused illumination reflection Lm (e.g.
  • the telan lens 18 which operates together with the relay lens 20 to create an image of the illumination region by the light emitted from the sample in the conjugate sample plane / detection plane CSP 2 and focus the illumination reflection on the conjugate aperture plane CAP 2 where the beam stop is located.
  • the illumination light Lm is substantially prevented from reaching the detection plane, thus significantly increasing signal to noise ratio of detection.
  • Fig. 3 illustrating schematically another example of the system configuration.
  • the system 10 of Fig. 3 is generally similar to that of Fig. 2, but exemplifies a folded collection path, as the case may be to serve a specific application.
  • an additional reflector 24 is provided, e.g. between the lenses 18 and 20.
  • the light source unit 12 may include a light emitter and a beam expander to provide a desired cross-sectional dimension of illuminating light beam Lm, and an illumination aperture 26 at the output of the light source unit.
  • the light propagation scheme is shown in Fig. 3 in a self explanatory manner.
  • the present invention can be easily implemented in an optical set up (e.g. microscope) of a given configuration.
  • the invention may provide a device installable in the optical system at a certain location with respect to the objective lens 14 and telan lens 18, and being formed by a relay lens 20 of a predetermined focal length and a beam stop (mask) 22 located at a certain distance from the relay lens.
  • the objective lens unit 14 although it is not intended to operate as a collimator, since it operates at/near its focal length, it can also collimate the illumination. Generally, the functions of the lenses used in the system changes depending on the direction of the light propagating through. For example, the objective lens performs collimation function for the illumination. It should further be understood that in any of the above described not limiting examples of the optical system, the configuration of the optical elements may be such that illuminating light is focused by the objective onto the sample, while the collected emission undergoes collimation.
  • the present invention provides a simple and effective solution for spatial separation between the illuminating light and emitted light in the collection/detection channel of an optical system. This eliminates or at least significantly reduces requirements for spectral filtering of light propagating from a sample under inspection, and provides unprecedented flexibility in multi-color imaging or spectral analysis on the emitted light.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Multimedia (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Microscoopes, Condenser (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

L'invention concerne un procédé optique et un système optique destinés à être utilisés pour l'examen d'un échantillon en détectant une émission stimulée/excitée optiquement à partir de l'échantillon, par exemple par fluorescence. Le système optique comprend un agencement de lentilles et un filtre spatial. L'agencement de lentilles définit un chemin d'éclairage pour diriger une lumière d'éclairage d'une première portée de longueur d'onde sur une région d'éclairage sur un plan d'échantillon et un chemin de collecte pour diriger une lumière d'éclairage réfléchie de la première portée de longueur d'onde et une lumière émise d'une seconde portée de longueur d'onde se propageant à partir du plan d'échantillon vers un plan de détection. L'agencement de lentilles comprend une pluralité de lentilles configurée pour focaliser la lumière d'éclairage réfléchie sur un plan d'ouverture conjugué et pour imager la région d'éclairage par la lumière émise collectée sur un plan d'échantillon conjugué correspondant au plan de détection, séparant ainsi spatialement des chemins optiques de la partie de lumière d'éclairage émise et réfléchie collectée à proximité d'un emplacement focal de la lumière réfléchie. Le filtre spatial peut définir une région de blocage de lumière dans le chemin de collecte dans le plan d'ouverture conjugué en un emplacement focal de la lumière d'éclairage réfléchie, empêchant ainsi sensiblement la lumière d'éclairage d'atteindre le plan de détection.
PCT/IL2014/050418 2013-05-16 2014-05-11 Procédé et système destinés à être utilisés pour l'examen d'échantillons par la détection d'une émission excitée optiquement provenant de l'échantillon WO2014184793A1 (fr)

Applications Claiming Priority (2)

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US201361823981P 2013-05-16 2013-05-16
US61/823,981 2013-05-16

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101651254B1 (ko) * 2015-07-22 2016-08-25 한국생산기술연구원 웨이퍼 평탄도 측정장치
CN109074674A (zh) * 2016-02-26 2018-12-21 南加州大学 具有选择性体积照射和光场检测的优化容积成像
JP7488587B2 (ja) 2019-04-03 2024-05-22 アッベリオー インストラメンツ ゲーエムベーハー 対物レンズに対する試料の変位を検出する方法及び装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6121603A (en) * 1997-12-01 2000-09-19 Hang; Zhijiang Optical confocal device having a common light directing means
WO2002086578A2 (fr) * 2001-04-24 2002-10-31 Yeda Research And Development Co. Ltd. Microscope a diffusion sur fond sombre de type a objectif
US6809324B1 (en) * 1999-05-19 2004-10-26 Carl Zeiss Jena Gmbh Scanning device, especially for detecting fluorescent light
US20110192976A1 (en) * 2010-02-10 2011-08-11 Halcyon Molecular, Inc. Aberration-correcting dark-field electron microscopy
EP2720074A2 (fr) * 2012-10-12 2014-04-16 Spectral Applied Research Inc. Filtre spatial pour combiner lumière d'excitation et lumière d'émission dans un microscope à balayage confocal episcopique multiplexé

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6121603A (en) * 1997-12-01 2000-09-19 Hang; Zhijiang Optical confocal device having a common light directing means
US6809324B1 (en) * 1999-05-19 2004-10-26 Carl Zeiss Jena Gmbh Scanning device, especially for detecting fluorescent light
WO2002086578A2 (fr) * 2001-04-24 2002-10-31 Yeda Research And Development Co. Ltd. Microscope a diffusion sur fond sombre de type a objectif
US20110192976A1 (en) * 2010-02-10 2011-08-11 Halcyon Molecular, Inc. Aberration-correcting dark-field electron microscopy
EP2720074A2 (fr) * 2012-10-12 2014-04-16 Spectral Applied Research Inc. Filtre spatial pour combiner lumière d'excitation et lumière d'émission dans un microscope à balayage confocal episcopique multiplexé

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101651254B1 (ko) * 2015-07-22 2016-08-25 한국생산기술연구원 웨이퍼 평탄도 측정장치
CN109074674A (zh) * 2016-02-26 2018-12-21 南加州大学 具有选择性体积照射和光场检测的优化容积成像
CN109074674B (zh) * 2016-02-26 2023-10-24 南加州大学 具有选择性体积照射和光场检测的优化容积成像
JP7488587B2 (ja) 2019-04-03 2024-05-22 アッベリオー インストラメンツ ゲーエムベーハー 対物レンズに対する試料の変位を検出する方法及び装置

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