WO2014005532A1 - Conjugate double-pass confocal measurement device with fluorescent mirror or phase conjugate mirror - Google Patents
Conjugate double-pass confocal measurement device with fluorescent mirror or phase conjugate mirror Download PDFInfo
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- WO2014005532A1 WO2014005532A1 PCT/CN2013/078831 CN2013078831W WO2014005532A1 WO 2014005532 A1 WO2014005532 A1 WO 2014005532A1 CN 2013078831 W CN2013078831 W CN 2013078831W WO 2014005532 A1 WO2014005532 A1 WO 2014005532A1
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- 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
- G01B9/04—Measuring microscopes
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- 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
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
-
- 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
- G01B11/22—Measuring arrangements characterised by the use of optical techniques for measuring depth
-
- 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
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
- G01B2210/56—Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth
Definitions
- This invention relates to optical microscopic measurement technology, and particularly to an ultra-precision non-contact measuring device used for measurement of line width, depth, and surface profile of three dimensional fine structures, micro-steps and micro grooves in micro optical components, micro mechanical components and integrated circuit components.
- Confocal scanning measurement is one of the important technologies used in the fields of micro-optics, micro-mechanics and micro-electronics to measure the line width, depth and surface profile of the fine structures, micro-steps and micro grooves of optical and mechanical components and integrated circuit components.
- a pinhole detector to suppress stray light in this measurement, the axial chromatographic capability is enabled.
- conventional confocal technique is always limited by the principle that the Numerical Aperture (NA) of a traditional lens imaging must be less than 1.
- One objective of the invention is to overcome the NA limitation for the axial resolution lies within the existing double-pass illumination confocal measurement and the confocal measurement and to solve double interference disturbances in double-pass illumination
- a conjugate double-pass confocal measurement device with a fluorescent mirror, which comprising a laser, a beam collimating and expanding module, a beam splitter, an objective lens (or objective in abbreviation), a three-axis stage, a narrow band filter, focusing lens, a transmitting fiber, and a light detector, the beam collimating and expanding module and the beam splitter are placed along the direct light path of the laser; the objective lens and the three-axis stage are placed along the reflected light path of the beam splitter; the narrow band filter and the focusing lens are placed along the transmitted light path of the beam splitter; the signal beam is focused by the focusing lens and transmitted to the light detector via the transmitting fiber; an elliptical mirror is placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen which is placed on the three-axis stage, and a fluorescent mirror is placed on a far focus of the laser
- the fluorescent mirror is a mirror with fluorescent coating or fluorescent liquid produced in the same way with the conventional fluorescent dyeing technique. So the fluorescent mirror is regarded as an existing technology. Under the illumination of ultra-short laser it can be used to create the excitation of single or multi-photon, thereby shifting the illumination light in frequency.
- the fluorescent mirror of the device functions to shift the input light in frequency, and separate it from the light used for the primary illumination and to illuminate the specimen for the second time, together with the monochromatic filter technology, the interference caused by the optical aliasing effect of primary and second illumination lights can be avoided.
- the conjugate double-pass illumination based on fluorescent mirror microscope the fluorescence characteristics of a fluorescent mirror is used to offset the illumination light, thereby avoiding the interference caused by the optical aliasing effect of the primary and second illumination lights. Meanwhile, monochromatic filter technology is used to effectively filter out the interference of the primary illumination light, thereby improving SNR ratio.
- the primary and second illumination lights are separated by frequency so that stray light can be suppressed and interference disturbance can be overcome and SNR can be improved.
- the drawback of conventional and double-pass illumination measurement technologies - - that the axial resolution is affected by the limitation of objective lens NA can be addressed.
- Another objective of this invention is to overcome the above-mentioned drawback, i.e. the limitation of axial resolutions of existing confocal measurement and double-pass illumination confocal measurement caused by NA of the collecting objective lens and to further enhance the capability of the system in measuring convex surfaces with large curvature.
- the objective of the invention is achieved by providing a conjugate double-pass confocal measurement device with a phase conjugate mirror which consists of a laser, a beam collimating and expanding module, a beam splitter, an objective lens, a three-axis stage, focusing lens, a transmitting fiber and a light detector, the beam collimating and expanding module and the beam splitter are placed along the direct light path of the laser; the objective lens and the three-axis stage are placed along the reflected light path of the beam splitter; the focusing lens is placed along the transmitted light path of the beam splitter, the signal beam is focused by the focusing lens and transmitted to the light detector via the transmitting fiber; an elliptical mirror is also placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen placed along the three-axis stage, and a phase conjugate mirror is placed along a far focus of the elliptical mirror.
- a phase conjugate mirror which
- the reflective light converged by the elliptical mirror will return along the input path, illuminating the convex surface with large curvature once again,
- This unique optical arrangement changes the light path of a conventional elliptical mirror under double-pass illumination, thus enabling the device to measure a convex surface with large curvature.
- the axial resolution can improve as the NA of the objective lens is increased.
- the provided conjugate double-pass illumination based on phase conjugate mirror microscope uses the characteristics of a phase conjugate mirror that the reflective light returns along the input path together and another characteristic that an elliptical mirror has a pair of isoplanatic conjugate foci.
- the device has a phase conjugate mirror, which functions to return the input light along the original path, so that the device is capable of measuring a convex surface with large curvature.
- phase conjugate mirror and an elliptical mirror makes the double-pass illumination possible, and the device is capable of measuring a convex surface with large curvatures.
- FIG 1 is a schematic diagram of conjugate double-pass confocal measurement device with a fluorescent mirror in accordance with one embodiment of the invention.
- FIG 2 shows the definition of coordinates for point spread function analysis of conjugate double-pass confocal measurement device with a fluorescent mirror.
- FIG 3 is the axial response curves for single photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
- FIG 4 is the lateral response curves for single photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
- FIG 5 is the axial response curves for double photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
- FIG 6 is the lateral response curves for double photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
- FIG 7 shows the structure of a conjugate double-pass confocal measurement device with a phase conjugate mirror in accordance with one embodiment of the invention.
- FIG 8 shows the definition of coordinate for point spread function analysis of elliptical mirror in conjugate double-pass confocal measurement device with a phase conjugate mirror.
- FIG 9 shows the phase conjugate mirror in conjugate double-pass confocal measurement device with a phase conjugate mirror.
- FIG 10 is the axial response curves of conjugate double-pass confocal measurement device with a phase conjugate mirror.
- FIG 11 is the lateral response curves of conjugate double-pass confocal measurement device with a phase conjugate mirror.
- a conjugate double-pass illumination based on fluorescent mirror microscope device comprises a laser 1, a beam collimating and expanding module 2, a beam splitter 3, objective lens 4, a three-axis stage 5, a narrow band filter 8, focusing lens 9, a transmitting fiber 10 and a light detector 11.
- the beam collimating and beam expanding system 2 and the beam splitter 3 are placed along the direct light path of the laser 1, the objective lens 4 and the three-axis stage 5 are placed along the reflected light path of the beam splitter 3, the narrow band filter 8 and the focusing lens 9 are placed along the transmitted light path of the beam splitter 3 .
- the signal beam is focused by the focusing lens 9 and is then transmitted to the light detector 11 via the transmitting fiber 10.
- An elliptical mirror 6 is also placed along the reflected light path of the beam splitter such that its near focus is located on a surface of a specimen placed on the three-axis stage 5.
- a fluorescent mirror 7 is placed on the far focus of the elliptical mirror 6.
- a linearly polarized beam with wavelength is provided by laser 1 and becomes an approximately ideal plane wave via beam collimating and expanding module 2; the beam is reflected by beam splitter 3 and then focused on the surface of specimen by focusing 4.
- the beam is reflected by elliptical mirror 6, and focused on fluorescent mirror 7 which is placed at the far focus of elliptical mirror 6.
- Pi is the far focus of elliptical mirror with coordinates (xi, yi, zi) where fluorescent mirror 7 is.
- P2 is the near focus of elliptical mirror with coordinates ( 2 ,_y 2 , z 2 ) where the specimen is placed. is the point on elliptical mirror where the light is reflected from Pi ioP 2 .
- n is the unit normal vector of elliptical surface at point M;
- rpiM is the distance from Pjto M;
- I"MP2 is the distance from to P 2 ;
- U P2 is the light wave function at point P 2;
- S is elliptical mirror 6
- h pl _ p2 represents the point spread function from plto p2, and it can be as shown below through simplification:
- fluorescent mirror 7 is a mirror with fluorescent coating or fluorescent liquid produced in the same way as the existing fluorescent dyeing technique. So the fluorescent mirror is regarded as an existing technology. Under the illumination of ultra-short laser, it can create the excitation of single or multi-photons, thereby offsetting the illumination light. - -
- the beam passes through focusing 4 and splits by beam splitter 3.
- the transmitted light passes through narrow band filters 8 where the scattered light with wavelength is absorbed, and the informative light with wavelength ⁇ 2 is transmitted and then focused on transmitting fiber 10 by focusing lens 9 and detected by light detector 11.
- I D is the light intensity distribution on detecting surface.
- pi- P2 is the point spread function from point / > ;to point P 2
- the conjugate double-pass confocal measurement device with a phase conjugate mirror consists of laser 12, beam collimating and expanding module 13, beam splitter 14, objective lens 15, three-axis stage 16, focusing lens 19, transmitting fiber 20 and light detector 21.
- the Beam collimating and expanding module 13 and the beam splitter 14 are placed along the direct light path of the laser 12; the objective lens 15 and the three-axis stage 16 are placed along the reflected light path of beam splitter 14, the focusing lens 19 lens is placed along the transmitted light path of the beam splitter 14; the signal beam is focused by the focusing lens 19 and then being transmitted to the light detector 21 via the transmitting fiber 20 .
- the system features that an elliptical mirror 17 is also placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror 17 is located on a surface of a specimen placed on the three-axis stage 16, and a phase conjugate mirror 18 is placed on a far focus of elliptical mirror 17.
- a linearly polarized beam comes out from laser source 12 and becomes an approximately ideal plane wave via beam collimating and expanding module 13; reflected by beam splitter 14 and then collected by objective lens 15.
- the beam is deflected though a big angle by the convex surface with large curvature; and then focuses on phase conjugate mirror 18 via elliptical mirror 17.
- Elliptical mirror 17 is different from a conventional lens model, and it needs theoretical derivation based on optical diffraction theory. As is shown in FIG.8, when its geometric expression
- Pi is the far focus of elliptical mirror with coordinates (x ls y ls z ⁇ ) where phase conjugate reflection mirror 18 is.
- P 2 is the near focus of elliptical mirror with coordinates (x 2 ,_y 2 , z 2 ) where the specimen is placed.
- M is the point where the light is reflected from Pi to P 2 .1t is the unit normal vector of the elliptical surface at point M;
- ⁇ is the distance from Pito M
- U P2 is the light wave function at point P 2
- U M is the lightwave function at point M
- S is elliptical mirror 17; - -
- h p ⁇ -p2 represents the point spread function from plto p2, and it can be as shown below through simplification:
- phase conjugate mirror 18 The beam is reflected by phase conjugate mirror 18 and returned along the original path to illuminate the specimen once again. As is shown in FIG 9, the working principle of phase conjugate mirror 18 is different from that of a conventional mirror.
- a monochromatic light wave with frequency of CO enters phase conjugate mirror 18 along the z-axis direction, and its electric field can be expressed as:
- the beam passes through focusing 15 and is projected by beam splitter 14, focused by focusing lens 19, transmitted though transmitting fiber 20 and then detected by light detector 21.
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Abstract
A conjugate double-pass confocal measurement device with a fluorescent mirror is disclosed, in which an elliptical mirror is placed along the reflected light path of a beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen which is placed on a three-axis stage, and a fluorescent mirror is placed on a far focus of the elliptical mirror.
Description
CONJUGATE DOUBLE-PASS CONFOCAL MEASUREMENT DEVICE WITH
FLUORESCENT MIRROR OR PHASE CONJUGATE MIRROR
TECHNICAL FIELD
This invention relates to optical microscopic measurement technology, and particularly to an ultra-precision non-contact measuring device used for measurement of line width, depth, and surface profile of three dimensional fine structures, micro-steps and micro grooves in micro optical components, micro mechanical components and integrated circuit components.
BACKGROUND ARTS
Confocal scanning measurement is one of the important technologies used in the fields of micro-optics, micro-mechanics and micro-electronics to measure the line width, depth and surface profile of the fine structures, micro-steps and micro grooves of optical and mechanical components and integrated circuit components. By introducing a pinhole detector to suppress stray light in this measurement, the axial chromatographic capability is enabled. However, conventional confocal technique is always limited by the principle that the Numerical Aperture (NA) of a traditional lens imaging must be less than 1.
The concept of double-pass illumination confocal measurement was proposed by C. J. R. Sheppard and T. Wilson in 1980 in the article "Multiple Traversing of the Object in the Scanning Microscope" (Journal of Modern Optics, 27: 5, 611-624). By reflecting the transmitted light coming out from the specimen to illuminate the specimen once again, the double-pass illumination response function gains a higher resolution. And according to the analysis, the axial resolution achievable with double-pass illumination confocal measurement is 2~4 times higher while the spot side lobe is better suppressed in comparison with conventional confocal measurement.
One of the significant drawbacks of conventional double-pass illumination confocal measurement is that interfere may incur on the interference of primary and secondary illuminations, and that the signal-to-noise (SNR) and axial resolution will be degraded. Moreover, the existing double-pass illumination confocal measurement and the confocal measurement put forward by Minsky have a common defect that while the surface with a relatively high curvature radius is being measured, the change in the normal direction of the surface leads the reflected measuring light to go beyond the collection aperture of the objective lens and so, such a specimen cannot be properly measured. In addition, the resolution of the system is closely related with the size of collection aperture; and the axial resolution increases as the size of the collective aperture increases. Due to the principle limitation that the imaging NA of a conventional lens is lower than 1, these two methods cannot be used to further improve the axial resolution by increasing NA.
- -
SUMMARY OF THE INVENTION
One objective of the invention is to overcome the NA limitation for the axial resolution lies within the existing double-pass illumination confocal measurement and the confocal measurement and to solve double interference disturbances in double-pass illumination
The purpose of this invention is achieved by providing a conjugate double-pass confocal measurement device with a fluorescent mirror, which comprising a laser, a beam collimating and expanding module, a beam splitter, an objective lens (or objective in abbreviation), a three-axis stage, a narrow band filter, focusing lens, a transmitting fiber, and a light detector, the beam collimating and expanding module and the beam splitter are placed along the direct light path of the laser; the objective lens and the three-axis stage are placed along the reflected light path of the beam splitter; the narrow band filter and the focusing lens are placed along the transmitted light path of the beam splitter; the signal beam is focused by the focusing lens and transmitted to the light detector via the transmitting fiber; an elliptical mirror is placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen which is placed on the three-axis stage, and a fluorescent mirror is placed on a far focus of the elliptical mirror.
The fluorescent mirror is a mirror with fluorescent coating or fluorescent liquid produced in the same way with the conventional fluorescent dyeing technique. So the fluorescent mirror is regarded as an existing technology. Under the illumination of ultra-short laser it can be used to create the excitation of single or multi-photon, thereby shifting the illumination light in frequency. The fluorescent mirror of the device functions to shift the input light in frequency, and separate it from the light used for the primary illumination and to illuminate the specimen for the second time, together with the monochromatic filter technology, the interference caused by the optical aliasing effect of primary and second illumination lights can be avoided.
In the conjugate double-pass illumination based on fluorescent mirror microscope, the fluorescence characteristics of a fluorescent mirror is used to offset the illumination light, thereby avoiding the interference caused by the optical aliasing effect of the primary and second illumination lights. Meanwhile, monochromatic filter technology is used to effectively filter out the interference of the primary illumination light, thereby improving SNR ratio. The conjugate double-pass illumination based on fluorescent mirror enables the response function to have a higher axial resolution, while the elliptical mirror can be used to realize high NA collection and detection (NA=1), and the axial resolution can therefore be further improved by increasing the NA.
This invention has the following advantages:
1) By using a fluorescent mirror and a narrow band filter, the primary and second illumination lights are separated by frequency so that stray light can be suppressed and interference disturbance can be overcome and SNR can be improved.
2) The drawback of conventional and double-pass illumination measurement technologies
- - that the axial resolution is affected by the limitation of objective lens NA can be addressed. The device in this invention can achieve double-pass illumination and detection when NA=1, and the resolution is improved by increasing NA.
3) A high order response function which is different from those of conventional confocal and double-pass illumination confocal systems is built in this invention and point scanning resolution is improved using this response function.
Another objective of this invention is to overcome the above-mentioned drawback, i.e. the limitation of axial resolutions of existing confocal measurement and double-pass illumination confocal measurement caused by NA of the collecting objective lens and to further enhance the capability of the system in measuring convex surfaces with large curvature.
The objective of the invention is achieved by providing a conjugate double-pass confocal measurement device with a phase conjugate mirror which consists of a laser, a beam collimating and expanding module, a beam splitter, an objective lens, a three-axis stage, focusing lens, a transmitting fiber and a light detector, the beam collimating and expanding module and the beam splitter are placed along the direct light path of the laser; the objective lens and the three-axis stage are placed along the reflected light path of the beam splitter; the focusing lens is placed along the transmitted light path of the beam splitter, the signal beam is focused by the focusing lens and transmitted to the light detector via the transmitting fiber; an elliptical mirror is also placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen placed along the three-axis stage, and a phase conjugate mirror is placed along a far focus of the elliptical mirror.
By incorporating the elliptical mirror and the phase conjugate mirror at far focus of the elliptical mirror, the reflective light converged by the elliptical mirror will return along the input path, illuminating the convex surface with large curvature once again, This unique optical arrangement changes the light path of a conventional elliptical mirror under double-pass illumination, thus enabling the device to measure a convex surface with large curvature. In comparison with the response function of a conventional confocal system, the response function of double-pass illumination has a higher axial resolution and can be used to achieve double-pass illumination with NA=1.
By providing the elliptical mirror with a pair of isoplanatic conjugate foci, the specimen is put on the near focus so that the signal light reflected from the specimen can be collected with NA=1, and that the specimen can be illuminated with NA=1 by the light reflected from the far focus. The axial resolution can improve as the NA of the objective lens is increased.
The provided conjugate double-pass illumination based on phase conjugate mirror microscope uses the characteristics of a phase conjugate mirror that the reflective light returns along the input path together and another characteristic that an elliptical mirror has a pair of isoplanatic conjugate foci. In the meantime, the elliptical mirror can also help the collection of light from a convex surface with large curvature when NA=1, which could enables the system to measure convex
- - surfaces with large curvature and improves the axial resolution of the system.
The device has a phase conjugate mirror, which functions to return the input light along the original path, so that the device is capable of measuring a convex surface with large curvature.
This invention has the following advantages:
1) The use of a phase conjugate mirror and an elliptical mirror makes the double-pass illumination possible, and the device is capable of measuring a convex surface with large curvatures.
2) The device can be used to achieve measurement and detection under double-pass illumination with NA=1, thereby improving the axial resolution of the system.
3) A high order response function which is different from those of conventional confocal and double-pass illumination confocal system is built in this invention and point scanning resolution is improved using this response function.
DESCRIPTION OF DRAWINGS
FIG 1 is a schematic diagram of conjugate double-pass confocal measurement device with a fluorescent mirror in accordance with one embodiment of the invention.
FIG 2 shows the definition of coordinates for point spread function analysis of conjugate double-pass confocal measurement device with a fluorescent mirror.
FIG 3 is the axial response curves for single photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
FIG 4 is the lateral response curves for single photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
FIG 5 is the axial response curves for double photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
FIG 6 is the lateral response curves for double photon stimulation in conjugate double-pass confocal measurement device with a fluorescent mirror.
FIG 7 shows the structure of a conjugate double-pass confocal measurement device with a phase conjugate mirror in accordance with one embodiment of the invention.
FIG 8 shows the definition of coordinate for point spread function analysis of elliptical mirror in conjugate double-pass confocal measurement device with a phase conjugate mirror.
FIG 9 shows the phase conjugate mirror in conjugate double-pass confocal measurement device with a phase conjugate mirror.
FIG 10 is the axial response curves of conjugate double-pass confocal measurement device with a phase conjugate mirror.
FIG 11 is the lateral response curves of conjugate double-pass confocal measurement device with a phase conjugate mirror.
Wherein
1 laser;
2 beam collimating and expanding module;
3 beam splitter,
4 objective lens;
5 three-axis stage,
6 elliptical mirror,
7 fluorescent mirror;
8 narrow band filter;
9 focusing lens,
10 transmitting fiber;
11 light detector;
12 laser;
13 beam collimating and expanding module;
14 beam splitter,
15 objective lens;
16 three-axis stage,
17 elliptical mirror
- -
18 phase conjugate mirror;
19 focusing lens;
20 transmitting fiber;
21 light detector.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Typical embodiments of this invention are now illustrated with reference to relevant figures attached. As shown in FIG 1, a conjugate double-pass illumination based on fluorescent mirror microscope device comprises a laser 1, a beam collimating and expanding module 2, a beam splitter 3, objective lens 4, a three-axis stage 5, a narrow band filter 8, focusing lens 9, a transmitting fiber 10 and a light detector 11. The beam collimating and beam expanding system 2 and the beam splitter 3 are placed along the direct light path of the laser 1, the objective lens 4 and the three-axis stage 5 are placed along the reflected light path of the beam splitter 3, the narrow band filter 8 and the focusing lens 9 are placed along the transmitted light path of the beam splitter 3 .The signal beam is focused by the focusing lens 9 and is then transmitted to the light detector 11 via the transmitting fiber 10. An elliptical mirror 6 is also placed along the reflected light path of the beam splitter such that its near focus is located on a surface of a specimen placed on the three-axis stage 5. Moreover, a fluorescent mirror 7 is placed on the far focus of the elliptical mirror 6.
The following is the measurement procedure for any measurement to be made:
Firstly, a linearly polarized beam with wavelength is provided by laser 1 and becomes an approximately ideal plane wave via beam collimating and expanding module 2; the beam is reflected by beam splitter 3 and then focused on the surface of specimen by focusing 4.
Secondly, the beam is reflected by elliptical mirror 6, and focused on fluorescent mirror 7 which is placed at the far focus of elliptical mirror 6. The beam coming out from fluorescent mirror
7 with wavelength λ2 is then focused by elliptical mirror 6 on specimen to illuminate the specimen for the second time.
Elliptical mirror 6 is different from a conventional lens model, and it needs theoretical derivation based on optical diffraction theory. As is shown in FIG 2, when its geometric expression is z I a + y I b + x I b = 1 , the response function of elliptical mirror 6 can be expressed as
- -
■dS0dxldyldzl (1)
where
O is the origin of coordinates
Pi is the far focus of elliptical mirror with coordinates (xi, yi, zi) where fluorescent mirror 7 is.
P2 is the near focus of elliptical mirror with coordinates ( 2,_y2, z2 ) where the specimen is placed. is the point on elliptical mirror where the light is reflected from Pi ioP2. n is the unit normal vector of elliptical surface at point M; rpiM is the distance from Pjto M;
I"MP2 is the distance from to P2;
UP2 is the light wave function at point P2;
[/ IS the light wave function at point M;
So is the ellipsoid where elliptical mirror 6 is;
S is elliptical mirror 6;
Taking the usual case into consideration, hpl_p2 represents the point spread function from plto p2, and it can be as shown below through simplification:
u
hPi-P2
The beam passes through focusing 4 and splits by beam splitter 3. The transmitted light passes through narrow band filters 8 where the scattered light with wavelength is absorbed, and the informative light with wavelength λ2 is transmitted and then focused on transmitting fiber 10 by focusing lens 9 and detected by light detector 11.
As is shown in FIG 3, the formula of double-pass illumination response function can be expressed as
ID ( ' Zs ) = (3)
where
ID is the light intensity distribution on detecting surface. pi-P2 is the point spread function from point />;to point P2
hi is the point spread function of focusing lens 4 is the wavelength of primary illumination λ2 is the wavelength of secondary illumination
It can be seen from equation (3) that, this invention builds up a high-order response function which is different from the existing conventional confocal and double-pass illumination confocal system and improves resolution of point scanning. FIG 3~6 are the axial and lateral response curves of objective lens 4 with NA=0.1 and NA=0.65 respectively.
Another typical implementation of this invention is illustrated in the drawing attached.
The conjugate double-pass confocal measurement device with a phase conjugate mirror consists of laser 12, beam collimating and expanding module 13, beam splitter 14, objective lens 15, three-axis stage 16, focusing lens 19, transmitting fiber 20 and light detector 21. The Beam collimating and expanding module 13 and the beam splitter 14 are placed along the direct light path of the laser 12; the objective lens 15 and the three-axis stage 16 are placed along the reflected light path of beam splitter 14, the focusing lens 19 lens is placed along the transmitted light path of the beam splitter 14; the signal beam is focused by the focusing lens 19 and then being transmitted to the light detector 21 via the transmitting fiber 20 .The system features that an elliptical mirror 17 is also placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror 17 is located on a surface of a specimen placed on the three-axis stage 16, and a phase conjugate mirror 18 is placed on a far focus of elliptical mirror 17.
- -
Measurement procedure of the above mentioned device is:
Firstly, a linearly polarized beam comes out from laser source 12 and becomes an approximately ideal plane wave via beam collimating and expanding module 13; reflected by beam splitter 14 and then collected by objective lens 15.
Secondly, the beam is deflected though a big angle by the convex surface with large curvature; and then focuses on phase conjugate mirror 18 via elliptical mirror 17.
Elliptical mirror 17 is different from a conventional lens model, and it needs theoretical derivation based on optical diffraction theory. As is shown in FIG.8, when its geometric expression
Where :
O is the origin of coordinates
Pi is the far focus of elliptical mirror with coordinates (xls yls z\) where phase conjugate reflection mirror 18 is.
P2 is the near focus of elliptical mirror with coordinates (x2,_y2, z2 ) where the specimen is placed.
M is the point where the light is reflected from Pi to P2.1t is the unit normal vector of the elliptical surface at point M;
Ρ; is the distance from Pito M;
rMp2 is the distance from to P2
UP2 is the light wave function at point P2,
UM is the lightwave function at point M;
So is the ellipsoid where elliptical mirror 17 is;
S is elliptical mirror 17;
- -
Taking the usual case into consideration, h p\-p2 represents the point spread function from plto p2, and it can be as shown below through simplification:
(2)
where the integral domain is the space surface consisting of all the light reflection points M.
The beam is reflected by phase conjugate mirror 18 and returned along the original path to illuminate the specimen once again. As is shown in FIG 9, the working principle of phase conjugate mirror 18 is different from that of a conventional mirror.
A monochromatic light wave with frequency of CO enters phase conjugate mirror 18 along the z-axis direction, and its electric field can be expressed as:
So it will exit as a conjugate wave with a reverse phase, which is inversed in the time flow in the states of amplitude, phase and polarization, and its electric field expression is:
It is different from a conventional mirror that the reflected beam will return along the original path, and as is shown in FIG 3, to illuminate the specimen once again, so that the device is suitable for the measurement of a convex surface with large curvature; and in comparison with a conventional confocal system, a double-pass illumination system has higher axial resolution, and it can also achieve high NA illumination (NA=1).
The beam passes through focusing 15 and is projected by beam splitter 14, focused by focusing lens 19, transmitted though transmitting fiber 20 and then detected by light detector 21.
The response signal received by light detector 21 contains the sample surface morphologic results corresponding to FIG 10 and FIG 11, and the curves in the figures represent objective lens 15 with NA=0.1 and NA=0.65 respectively.
Claims
WHAT IS CLAIMED IS:
1, A conjugate double-pass confocal measurement device with a fluorescent mirror, which comprises a laser, a beam collimating and expanding module, a beam splitter, an objective lens, a three-axis stage, a narrow band filter, focusing lens, a transmitting fiber, and a light detector, the beam collimating and expanding module and the beam splitter are placed along the direct light path of the laser; the objective lens and the three-axis stage are placed along the reflected light path of the beam splitter; the narrow band filter and the focusing lens are placed along the transmitted light path of the beam splitter; the signal beam is focused by the focusing lens and transmitted to the light detector via the transmitting fiber; an elliptical mirror is placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen which is placed on the three-axis stage, and a fluorescent mirror is placed on a far focus of the elliptical mirror.
2, A conjugate double-pass confocal measurement device with a phase conjugate mirror, which comprises a laser, a beam collimating and expanding module, a beam splitter, an objective lens, a three-axis stage, focusing lens, a transmitting fiber and a light detector, the beam collimating and expanding module and the beam splitter are placed along the direct light path of the laser; the objective lens and the three-axis stage are placed along the reflected light path of the beam splitter; the focusing lens is placed along the transmitted light path of the beam splitter, the signal beam is focused by the focusing lens and transmitted to the light detector via the transmitting fiber; an elliptical mirror is also placed along the reflected light path of the beam splitter such that a near focus of the elliptical mirror is located on a surface of a specimen placed along the three-axis stage, and a phase conjugate mirror is placed along a far focus of the elliptical mirror.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1422449.7A GB2517627B (en) | 2012-07-05 | 2013-07-04 | Conjugate double-pass confocal measurement device with fluorescent mirror or phase conjugate mirror |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012102448259A CN102818522A (en) | 2012-07-05 | 2012-07-05 | Phase conjugate reflection bi-pass lighting confocal microscopic device |
| CN201210244838.6 | 2012-07-05 | ||
| CN201210244838.6A CN102759331B (en) | 2012-07-05 | 2012-07-05 | Conjugated bi-pass lighting confocal microscopic device of fluorescent reflecting mirror |
| CN201210244825.9 | 2012-07-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2014005532A1 true WO2014005532A1 (en) | 2014-01-09 |
Family
ID=49881351
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/CN2013/078831 WO2014005532A1 (en) | 2012-07-05 | 2013-07-04 | Conjugate double-pass confocal measurement device with fluorescent mirror or phase conjugate mirror |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2517627B (en) |
| WO (1) | WO2014005532A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106931888B (en) * | 2017-03-29 | 2019-07-02 | 浙江大学 | A kind of double light path type laser displacement sensor |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07209187A (en) * | 1993-11-30 | 1995-08-11 | Omron Corp | Laser scanning type cell analyser |
| CN101939635A (en) * | 2008-02-04 | 2011-01-05 | 皇家飞利浦电子股份有限公司 | Molecular diagnostic system based on evanescent illumination and fluorescence |
| CN102759331A (en) * | 2012-07-05 | 2012-10-31 | 哈尔滨工业大学 | Conjugated bi-pass lighting confocal microscopic device of fluorescent reflecting mirror |
| CN102818522A (en) * | 2012-07-05 | 2012-12-12 | 哈尔滨工业大学 | Phase conjugate reflection bi-pass lighting confocal microscopic device |
-
2013
- 2013-07-04 GB GB1422449.7A patent/GB2517627B/en not_active Expired - Fee Related
- 2013-07-04 WO PCT/CN2013/078831 patent/WO2014005532A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07209187A (en) * | 1993-11-30 | 1995-08-11 | Omron Corp | Laser scanning type cell analyser |
| CN101939635A (en) * | 2008-02-04 | 2011-01-05 | 皇家飞利浦电子股份有限公司 | Molecular diagnostic system based on evanescent illumination and fluorescence |
| CN102759331A (en) * | 2012-07-05 | 2012-10-31 | 哈尔滨工业大学 | Conjugated bi-pass lighting confocal microscopic device of fluorescent reflecting mirror |
| CN102818522A (en) * | 2012-07-05 | 2012-12-12 | 哈尔滨工业大学 | Phase conjugate reflection bi-pass lighting confocal microscopic device |
Non-Patent Citations (1)
| Title |
|---|
| ZHAO, WEIQIAN ET AL.: "Tri-heterodyne confocal microscope with axial superresolution and higher SNR.", OPTICS EXPRESS., vol. 12, no. 21, October 2004 (2004-10-01), pages 5191 - 5197 * |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2517627B (en) | 2018-03-21 |
| GB2517627A (en) | 2015-02-25 |
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