Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/28—Investigating the spectrum
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/02—Details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/02—Details
  • G01J3/0256—Compact construction
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/28—Investigating the spectrum
  • G01J3/44—Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• • 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
  • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
  • G02B21/0032—Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers
• • 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
  • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
  • G02B21/0052—Optical details of the image generation
  • G02B21/0076—Optical details of the image generation arrangements using fluorescence or luminescence

Definitions

• the invention relates to a miniaturized confocal spectrometer with integrated illumination device for radiation emitted by an optically active object.
• the invention aims to increase the sensitivity achieved so far with known miniaturized spectrometers and to expand the fields of application of such spectrometers for low-intensity radiation sources, such as backscattering objects with light-induced emission spectra such as Raman scattering or fluorescence radiation from molecules or atoms the amount of substance available is in the range of micrograms or nanograms.
• confocal optical devices - such as microscopes and spectrometers - is the output-side focal point of the illumination beam path in the input-side focal point of the imaging or detection beam path.
• the optical axis of this beam path may coincide with the axis of the illumination beam path, or both axes may be inclined to each other.
• the illumination beam path includes a light source, a pinhole, a collimator, a bandpass filter, a dichroic beam splitter, and a condenser lens.
• the pinhole lies in the input side focal point of the collimator.
• the converging lens forms the pinhole in the output side focal point of the illumination beam path.
• the focus is on or in the object to be examined.
• the axis of the dichroic beam splitter is inclined to the axis of the illumination beam path.
• the detection beam path starts at the output focal point of the condenser lens (confocal image).
• the optical axis of the detection beam path first passes through ⁇ k, converging lens at the end of the illumination beam path; this axis becomes the dichokitic Beam splitter deflected from the optical axis of the illumination beam path.
• the detection beam path may optionally include a deflection mirror.
• the detection beam path includes an edge filter and a condenser lens which collects the light at its output focal point.
• the bandpass filter filters out the wavelength range suitable for the excitation of the emitted radiation.
• the dichroic beam splitter With the dichroic beam splitter, the light emitted from a object to be examined, which is located at the focal point of the illumination beam path, and the reflected illumination light are deflected.
• the edge filter Long-pass or short-pass filter filters out the appropriate wavelength range in which the wavelength of the radiation emitted by the object to be examined is located.
• the size of the light source and its heat development require a certain distance between the light source and the miniaturized spectrometer. This distance is generally bridged with an optical fiber.
• the light is preferably supplied via this optical fiber whose end is located at the focal point of the collimator at the entrance to the illumination beam path.
• the light emanating from an illuminated object is preferably supplied from the detection beam path via a further optical fiber to the entrance slit of the spectrometer.
• the beginning of the further optical fiber lies at the focal point of the convergent lens at the output of the detection beam path.
• the spectrometer generates the spectrum of the radiation emitted by an illuminated object.
• the spectrum can be viewed visually on a screen, or it can be evaluated and displayed electronically.
• Microspectrometer includes an entrance slit, a planar waveguide for incident and spectrally resolved light, a self-focusing reflection grating and other optical functional elements.
• the spectrally split light falls on a diode array from which the spectrum is fed to an evaluation unit.
• the miniaturized spectrometer should not require any subsequent adjustment by the user.
• the miniaturized spectrometer should also be suitable for the investigation of objects containing a low concentration of the substance to be detected (molecules or atoms), and which tolerate only a low radiation dose or are heat-sensitive. Furthermore, it should be mobile and used under difficult conditions and can be used by untrained people.
• the inventive miniaturized confocal spectrometer for the spectral examination of a radiation emitted by an optically active object comprises the following components:
• a known microspectrometer as one of the assemblies of the miniaturized confocal spectrometer.
• the light source may be a conventional thermal light source, or one of the known laser light sources.
• the radiation of the light source is collected in the input-side focal point of the illumination beam path.
• the illumination beam path comprises a converging lens at its input, optionally a bandpass filter, a dichroic beam splitter and a converging lens at its output.
• a bandpass filter can be filtered out of the radiation of the light source, a desired spectral range, which is suitable for exciting the emission radiation of the object.
• the dichroic beam splitter is tilted against the optical axis of the illumination beam path.
• the angle of inclination of the beam splitter against the optical axis of the illumination beam path can be from 30 ° to 60 °.
• the optical axis of the detection beam path is thus deflected by an angle of 60 ° to 120 °, preferably of 90 °, from the optical axis of the illumination beam path.
• the radiation of the light source is collected in the output side focal point of the illumination beam path.
• the object to be examined is arranged in the vicinity of this focal point.
• the illumination radiation excites emission radiation of the object.
• the detection beam path begins at the output-side focal point of the illumination beam path and passes through the converging lens at the output of the illumination beam path. With the dichroic beam splitter, the emission radiation emanating from the object to be examined is deflected out of the illumination beam path.
• an edge filter (long-pass filter or short-pass filter) is arranged in the detection beam path.
• the position of the filter edge is matched to the wavelength of the emission radiation to be examined.
• the radiation emitted by the object to be examined is conducted by means of a converging lens at the output of the detection beam path to the entrance slit of the microspectrometer.
• the input of the detection beam path coincides from the confocal focal point to the dichroic beam splitter with the output of the illumination beam path.
• the spectrum of the emission radiation entering the entrance slit of the examined object is generated.
• the microspectrometer preferably comprises a self-focussing corrected reflection grating with unsymmetrical threefold furrows.
• the spectrum is preferably located on a diode array, with which it is read out and evaluated.
• a slit diaphragm with an oblong slit is located in the vicinity of the input-side focal point of the illumination beam path.
• the radiation of the thermal light source is focused on the gap in the slit diaphragm.
• the slit diaphragm is located in or near the entrance-side focal point of the converging lens of the illumination beam path. This creates a bundle of rays whose cross section has the shape of an elongated ellipse.
• the gap in the slit may be from 10 to 100 microns wide and from 50 to 500 microns high.
• the cross section of the light beam emerging from the gap has the shape of an elongated ellipse.
• the length ratio of the two major axes of the ellipse can be from 2 to 1 to 10 to 1.
• a diode edge emitter can be used, preferably with stabilized wavelength.
• a surface of the edge emitter emitting the illumination radiation is arranged in the vicinity of the input-side focal point of the illumination beam path.
• the radiator surface can be 2 to 5 square microns in size. In this case, neither a sierangs adopted for emanating from the edge radiator radiation nor a slit diaphragm are required.
• the edge radiator produces a diverging light beam.
• the divergence angles of the beam are different in size in two directions of the beam cross section.
• the beam receives an elongated elliptical cross section.
• the length ratio of the two main axes of the ellipse can be from 2 to 1 to 10 to 1.
• no slit diaphragm is used.
• the beam entering the illumination beam path has an elongated elliptical cross section, with which an elliptical light spot is produced on the object to be examined at the exit of the illumination beam path.
• the object emits a radiation whose spectrum is to be investigated.
• the radiation emitted by the object has a different wavelength than the incident via the illumination beam path excitation radiation. A portion of this emitted radiation exits the object to be examined in the direction of the converging lens at the output of the detection beam path.
• the emitted beam also has an elongated elliptical cross section. This beam passes through the condenser lens at the exit of the illumination beam path and falls on the dichroic beam splitter, which redirects the emitted beam into the detection beam path. Due to the converging lens at the output of the detection beam path, the beam emitted by the object with an elliptical cross section is directed to the entrance slit of the microspectrometer.
• the major major axis of the elliptical cross section of the beam falling on the entrance slit of the microspectrometer is parallel to the longitudinal axis of the entrance slit.
• the entrance slit of the microspectrometer is preferably complete and in its entirety Surface illuminated approximately evenly.
• the elliptical cross section of the beam is preferably only slightly larger than the area of the entrance slit.
• the converging lenses in the illumination beam path and in the detection beam path can be conventional refractive ground single collector lenses or one conventional system each of refractive ground lenses made of optical glass or plastic. Instead, diffractive lenses (Fresnel zone plates) can be used as converging lenses. Furthermore, glass tips with flat-ground ends and with a radial gradient of the refractive index (GRIN lenses) can be used as converging lenses.
• the typical diameter of GRIN lenses is from 0.5 to 5 millimeters, and the typical length is from 2 to 20 millimeters.
• the dichroic beam splitter may be composed of two 45 degree prisms. On the inner surface of one of the prisms, the dichroic splitter mirror is applied (for example by vapor deposition). The inner surfaces of the two prisms lie on each other. Further, the dichroic beam splitter mirror may be mounted on a transparent plate which lies between the inner surfaces of both prisms.
• the dichroic beam splitter made up of two 45-degree prisms, allows a very compact design and facilitates the composition of the optical system when using GRIN lenses and plate-shaped filters.
• the microspectrometer has a self-focusing - and preferably corrected - reflex ionsgitter.
• the reflection grating preferably has triangular-shaped asymmetrical grooves.
• the entrance slit of the microspectrometer lies in the focal point of the converging lens at the exit of the detection beam path or in the immediate vicinity of this focal point.
• the spectrum generated at the reflection grating preferably falls on a diode array.
• the illumination beam with the cross-section of an elongated ellipse generates a light spot with an elliptical cross-section on the object to be examined at the output-side focal point of the illumination beam path.
• the beam emitted by the object in this light spot also has an elliptical cross section.
• This elliptical light spot is imaged via the detection beam path on the entrance slit of the microspectrometer.
• the large main axis of the elliptical cross section of the steel bundle in the detection beam path runs parallel to the longitudinal axis of the entrance slit of the microspectrometer.
• the entrance slit of the microspectrometer is completely and approximately evenly illuminated by the radiation emitted by the object under investigation.
• the cross-sectional area of the beam on the entrance slit is only slightly larger than the area of the entrance slit.
• the radiation emitted by the object being examined, which is picked up by the converging lens at the entrance of the detection beam path, is collimated with only a small loss on the entrance slit of the spectrometer.
• the entrance slit is fully illuminated.
• the entrance slit of the microspectrometer is typically from 10 to 100 microns wide and from 150 to 500 microns high.
• the assemblies of the miniaturized spectrometer include the illumination unit, the optical components for the illumination beam path, the optical components for the detection beam path, the concave reflection grating micro-spectrometer and with - preferably electronic - readout unit for the spectrum. These assemblies are optically adjusted during assembly. They are rigidly connected with each other and permanently.
• the miniaturized spectrometer is - from the user's point of view - a "one-piece" device. Typical external dimensions are 20 millimeters wide, 60 millimeters long and 10 millimeters thick.
• the miniaturized spectrometer may preferably be used for the investigation an object which emits radiation of a different frequency under the action of the incident excitation radiation, for example as Raman radiation or as fluorescence radiation. It is particularly suitable for examining low-faint emission sources, for example surface-enhanced Raman spectroscopy (SERS), preferably on microscopically small objects.
• SERS surface-enhanced Raman spectroscopy
• the miniaturized confocal spectrometer according to the invention has the following advantages: 0
• the beam bundle of elliptical cross section entering the illumination beam path from the light source falls completely on the object to be examined.
• the object emits a beam of elliptical cross-section which uniformly illuminates the entrance slit of the microspectrometer, but has only a low intensity next to this entrance slit.
• the optical sensitivity of the miniaturized spectrometer according to the invention is greater by a factor of 10 to 100 than the sensitivity of a fiber-based miniaturized spectrometer.
• the miniaturized spectrometer is mechanically and thermally robust due to the quasi-monolithic structure.
• the radiation losses of the radiation emitted by an object at the entrance slit of the microspectrometer are low.
• the low-power illumination allows the further miniaturization of the known miniaturized spectrometer and results in a lower thermal load of the object to be examined a Because of short transmission paths, the risk of parasitic spectra is low.
• Filtering of the laser light in the illumination beam path are dispensed with. ° It is particularly suitable for on-site microanalysis, for example for the Point of
• the miniaturized spectrometer is suitable for the microspectroscopic analysis of small amounts of substances as well as for the trace analysis of atoms or molecules present in an object in very low concentrations.
• Fig. 1 shows a schematic diagram of a miniaturized spectrometer according to the prior art.
• the radiation of the light source (101) is conducted by means of the optical fiber (102) to the input-side focal point (103) of the converging lens (104) of the illumination beam path.
• a bandpass filter (105) may be present in the illumination beam path.
• the light passes through the inclined against the optical axis of the illumination beam path dichroic beam splitter (106) on the converging lens (107) at the output of the illumination beam path.
• the illumination radiation is collected in the output-side focal point (108) of the illumination beam path. At this focal point an object to be examined (109) is attached.
• the illumination radiation can excite atoms or molecules in the object.
• the radiation emitted by the object for example Raman scattered radiation or fluorescence radiation, is the detection radiation. This starts from the object in the confocal focal point (108) and steps in the detection beam path. From the converging lens (107) at the entrance of the detection beam path, the detection radiation strikes the dichroic beam splitter (106). The beam splitter deflects the detection radiation together with the deflecting mirror (110). In the illustrated arrangement, the optical axis of the detection beam path runs, for example, parallel to the optical axis of the B ⁇ leuchtungsstrahienganges.
• an edge filter (11 1) and a condenser lens (112) are further attached at the end of the detection beam path.
• the converging lens (112) collects the emitted radiation at its focal point (1 13). From the focal point (113), the detection radiation is conducted by means of an optical fiber (114) to the entrance slit of the spectrometer (115).
• the illumination beam path extends from the light source (101) to the confocal focal point (108).
• the detection beam path extends from the confocal focal point (108) to the spectrometer (115).
• Fig. 2 shows an exemplary arrangement of the optical components of the miniaturized spectrometer according to the invention.
• the light of a thermal light source (201) is collected at the focal point (203) by means of a focusing device.
• a slit diaphragm is arranged at the focal point (203).
• the focal point (203) is simultaneously the input side focal point of the collecting lens (204) of the illumination beam path.
• the dichroic beam splitter (206) the illumination radiation is directed to the converging lens (207). This converging lens collects the illumination radiation in the output-side focal point (208) of the illumination beam path.
• the object to be examined (209) is arranged.
• the radiation emitted by the object (209) is the detection radiation.
• the detection radiation impinges on the dichroic beam splitter (206).
• the beam splitter deflects the detection radiation from the illumination beam path.
• This converging lens collects the detection radiation at the focal point (213), at which the entrance slit of the microspectrometer (215) is located.
• the components of the miniaturized spectrometer are the light source (A), the illumination beam (B) and the microspectrometer (C).
• a laser diode can be used instead of a thermal light source. Its exit window is arranged in the focal point (203). In this case, no slit diaphragm is required.
• FIG 3 shows an embodiment of a dichroic beam splitter (206).
• This embodiment comprises two 45 degree prisms (301 and 302), the inner surfaces (303) of which lie on top of each other. Preferably, one of these surfaces carries an optically active coating.
• a GRIN lens (305) and a band pass filter (306) are located at the entrance to the illumination beam path, ahead of which the light source lies in the assembly (A).
• a GRIN lens (307) forms the output of the illumination beam path in front of which the object is located.
• the beam splitter inner surface (303) the radiation emitted by the object is deflected into the detection beam path.
• the edge filter (308) and a GRIN lens (309) the emitted radiation falls on the entrance slit of the microspectrometer in the assembly (C).
• Fig. 4 shows another embodiment of the dichroic beam splitter. Between the two 45 degree prisms (401 and 402) is a plate (403) bearing a dichroic layer on one of its faces.

Landscapes

• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Optics & Photonics (AREA)
• Spectrometry And Color Measurement (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Microscoopes, Condenser (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=42651140

Family Applications (1)

Country Status (4)

Cited By (2)

Families Citing this family (3)

Citations (4)

Family Cites Families (8)

• 2010
  • 2010-05-11 WO PCT/EP2010/056495 patent/WO2010133485A1/de not_active Ceased
  • 2010-05-11 JP JP2012510277A patent/JP5628903B2/ja not_active Expired - Fee Related
  • 2010-05-11 EP EP10718218.0A patent/EP2430415B1/de not_active Not-in-force
  • 2010-05-13 US US12/779,368 patent/US8525988B2/en not_active Expired - Fee Related

Patent Citations (4)

Also Published As

Similar Documents

Legal Events