KR101261271B1

KR101261271B1 - Optical apparatus

Info

Publication number: KR101261271B1
Application number: KR1020100103233A
Authority: KR
Inventors: 이재용; 이은성; 문대원; 임천석
Original assignee: 한국표준과학연구원
Priority date: 2010-10-22
Filing date: 2010-10-22
Publication date: 2013-05-07
Also published as: KR20120041863A

Abstract

The present invention provides an optical device. The optical device comprises a scanning unit for providing parallel beams for scanning, an adapter lens module (ALM) for providing parallel beams to form focal loci on a common image plane (IIP), and focusing the focal loci on a sample And a probe lens module (PLM) that can be delivered to the top surface and inserted into the sample.

Description

Optical device {OPTICAL APPARATUS}

The present invention relates to an optical device, and more particularly, to an objective lens system of a Coherent Anti-Stokes Raman Scattering (CARS) bio microscope.

Bioimaging technologies such as CARS (Coherent Anti-Stokes Raman Scattering) biomicroscopy are advanced science technologies that can identify or solve the mechanism of intractable diseases facing humanity. Unlike CARS biomicroscopy techniques, conventional confocal reflection microscopy-based imaging techniques use several types of fluorescent pigments in tissues. Fluorescent pigments are non-toxic and require to penetrate deep into the tissue for tomography. Problems such as safety problems of fluorescent dyes, inefficient diagnostics dependent on fluorescent dyes, and reduced contrast of photographed images due to inhomogeneity of fluorescent dyes are caused.

One technical problem to be solved of the present invention is to provide an objective lens system (objective) for CARS imaging.

An optical device according to an embodiment of the present invention is a scanning unit for scanning a parallel beam in a specific angle range, the adapter lens module for providing the parallel beam to form focal trajectories on a common image plane (IIP) (Adaptor Lens) Moudle (ALM), and a probe lens module (PLM) capable of focusing the focal trajectories on a sample, delivering the sample to a sample top surface, and inserting the sample into the sample.

The optical device according to an embodiment of the present invention may provide an objective lens system for inserting a biological sample without aberration and difference in focal length with respect to the pump beam and the Stokes beam.

1 is a view illustrating a CARS optical device according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a nosepiece according to an embodiment of the present invention.
3 is a view for explaining an optical device according to an embodiment of the present invention.
4 is an enlarged view of the PLM of FIG. 3.
5 are computer simulation results illustrating the performance of the PLM described with reference to FIG. 4.
6, A spot diagram of the PLM described in FIG. 4 is shown.
7 illustrates a geometric optical relationship between an ALM and a PLM of an optical device according to another embodiment of the present invention.
FIG. 8 is a view for explaining an optical device that satisfies the condition obtained in FIG. 7.
9 shows a spot diagram of the ALM of FIG. 8.
10 illustrates optical characteristics when the PLM of FIG. 4 and the ALM of FIG. 7 are combined.

The CARS microscope apparatus according to the present invention measures the intrinsic vibration characteristic of each molecule using laser nonlinear optical phenomena without administering a fluorescent substance to single cells and tissues. Therefore, the CARS microscope device can observe the cells in a live state in real time. In addition, the CARS microscopy device can take internal cross-sections in three-dimensional stereoscopic images without cutting the cells, and can be observed with a spatial resolution of about 300 nanometers, ranging from cells of several micrometers in size to biological tissues ranging from several millimeters. .

On the other hand, in order for the CARS microscope device to observe in-vivo, an endoscope microscope optical system is required. That is, an optical design of a microscope nosepiece for CARS imaging is required.

When two pulses of different wavelengths, the pump beam ω _P and the Stokes beam ω _S , simultaneously focus in a biological sample, a CARS signal is generated at this focus, and the CARS signal is imaged on the sensing side.

When two pulses represented by the pump beam ω _P and the Stokes beam ω _S are focused at one point without chromatic aberration, the living body can effectively generate the CARS signal. CARS signals are associated with tertiary induced polarization effects. That is, the generation amount of the CARS signal is proportional to the product of the power of the pump beam intensity and the power of the Stokes beam intensity. Thus, the quality of the focused beam affects the performance of the CARS microscope.

The size of the CARS microscope optics should be small so that they can be inserted and used in vivo. In addition, the aberration characteristics of the CARS microscope optical system should have a diffraction-limited performance. In addition, in the pump beam ω _P and the Stokes beam ω _S , the diffraction limit performance of the two wavelengths must match at one point. Therefore, the CARS microscopy optical system must satisfy a much more stringent aberration condition than the optical system used for the confocal endoscope type optical microscope. On the other hand, the wavelength used to generate the CARS signal is preferably used in the wavelength of the near infrared region having a high transmittance into the living body rather than the visible light region. For example, the wavelength of the pump beam may be 817 nm and the wavelength of the Stokes beam may be 1064 nm.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the invention to those skilled in the art. In the drawings, the components have been exaggerated for clarity. Portions denoted by like reference numerals denote like elements throughout the specification.

1 is a view illustrating a CARS optical device according to an embodiment of the present invention.

Referring to FIG. 1, the optical apparatus includes a scanning unit 130 that provides a parallel beam for scanning, and an adapter lens module that provides the parallel beam 130 to form focal trajectories on a common image plane (IIP). (Adapter Lens Module; ALM) 160, and a probe lens module (PLM) capable of focusing the focal trajectories on the sample 190 and delivering them to a sample image plane and inserting them into the sample 190 170).

The light source unit 110 may include a first pulse laser 114 providing a stokes beam ω _S and a second pulse laser 112 providing a pump beam ω _P. The light source unit 110 may include a dichroic mirror 116 and a reflector 118. The Stokes beam ω _S may travel through the dichroic mirror 116. In addition, the pump beam ω _P may be reflected by the reflector 118 so that the path is changed and reflected by the dichroic mirror 116 again. Accordingly, the stokes beam ω _S and the pump beam ω _P may have the same optical path.

The beam extension unit 120 may enlarge the size of the beam of the Stokes beam and the pump beam. For example, the first lens 122 and the second lens 124 having the same focus point may enlarge the size of the Stokes beam and the pump beam to provide the parallel light.

The scanning unit 130 may include at least two tilting mirrors 132 and 134. As the tilting mirrors 132 and 134 move, the parallel light incident on the scanning unit 130 may be spatially scanned.

The reflector 142 may change the optical path of the parallel light provided by the scanning unit 130 to provide the nosepiece 180. The nosepiece 180 may include an adapter lens module 160 and a probe lens module 170.

The CARS signal generated in the sample 190 is provided to the dichroic mirror 144 through the probe lens module 170 and the adapter lens module 160. The dichroic mirror 144 changes the optical path of the CARS signal and provides it to the detector 150.

The sensing unit 150 may include a light receiving element. The sensing unit 150 may include an optical filter. A focusing lens 146 may be disposed between the sensing unit 150 and the dichroic mirror 144. The focusing lens 146 may focus and provide the CARS signal to the sensing unit 150.

The nosepiece for CARS imaging is a lens system having a long and thin structure like a sharp pencil. Typically, probes for confocal microscopy use GRIN lenses. The GRIN lens is a gradient index lens whose refractive index changes in the radial direction. The GRIN lens has a significant amount of aberration in the GRIN lens itself, and generates large chromatic aberration. Thus, the GRIN lens is inadequate as an object optical system for processing the CARS signal.

A nosepiece, which is an elongated lens system, may include the PLM 160 and the ALM 170. The PLM 170 is a lens unit inserted into a living body through a small hole. The ALM 160 optically connects the scanning unit 130 and the PLM 170 to operate the PLM 170.

There is a common image plane common between the ALM 160 and the PLM 170. When the scanning beam is incident on the ALM 160, the ALM 160 forms a focal point on the common upper surface IIP. The PLM 170 focuses and transmits the focal locus on a sample upper surface (SIP) of the biological sample. When the focal trajectories are focused on the aberration-free points in the biological sample 190, a CARS signal is generated at the focused points. The CARS signal is again transmitted to the detector 150 through the PLM 170, the ALM 160, and the dichroic mirror 144.

Numerical aperture is the ability of an optical system to collect light. The numerical aperture is divided into a numerical aperture at object side (NAO) and a numerical aperture at image side (NAI). The numerical aperture at image side (NAI) is equal to the sample side numerical aperture (NAS). The object side refers to the ALM side, and the image side refers to the biological sample side.

The amount of the CARS signal collected by the nosepiece 180 is proportional to the square of the sample side numerical aperture (NAS). Optical resolution is proportional to the square of the sample side numerical aperture (NAS). Preferably, the size of the sample-side numerical aperture (NAS) may be 0.5 or more to generate the CARS signal. More preferably, the size of the sample-side numerical aperture (NAS) may be 0.6 to 0.8.

2 is a conceptual diagram illustrating a nosepiece according to an embodiment of the present invention.

Referring to FIG. 2, the nosepiece 180 may be an elongated lens system. For the elongated nosepiece, the focal length of the nosepiece 180 is required to be at least 10 mm. In addition, for the CARS signal to be generated effectively, the sample side numerical aperture (NAS) is required to be 0.5 or more.

Therefore, when the sample-side numerical aperture (NAS) is 0.5 or more, when the nosepiece 180 is configured by only one module, the focal length of the nosepiece 180 is about 3 mm. Therefore, when the focal length of the nosepiece 180 is 10 mm or more and the sample side numerical aperture NAS of the nosepiece 180 is 0.5 or more, the nosepiece 180 is connected to a probe lens module (PLM). It can only be separated by an adapter lens module (ALM).

When the nosepiece 180 includes the PLM and the ALM, an optical clear aperture of the PLM is 3.5 mm or less, and a fied of view in sample side (FOVS) is 0.22 mm or less. The side numerical aperture (NAS) may be 0.5 to 0.8 for water immersion. In addition, the length of the PLM (distance of the SIP from the IIP) may be 20 mm or more. The nosepiece 180 that meets the above conditions may be suitable for biometric insertion for CARS signal measurement. Also, the ALM can be designed for PLM that meets the above conditions.

3 is a view for explaining an optical device according to an embodiment of the present invention.

4 is an enlarged view of the PLM of FIG. 3.

3 and 4, in order for the nosepiece to be elongated, a common image height η and a sample side numerical aperture NAS are considered. The size of the optical aperture is determined primarily by the numerical aperture (NAS) on the sample side. In order to make the lens system longer, the distance LL between the object plane and the first lens plane is increased. Increasing the distance LL causes an increase in the optical aperture. The most important requirements of the PLM 170 that can be inserted into a living body are summarized as follows.

(1) The optical clearness of the PLM is 3.5 mm or less.

(2) The length of PLM (distance of SIP in IIP, LS) is 20 mm or more.

(3) Sample side numerical aperture (NAS) is 0.5 or more for water immersion.

(4) The view of sample in sample side (FOVS) is 0.22 mm or less.

(5) PLM is composed of eight or more lenses (171 ~ 178), the lenses constituting the PLM is composed of a flat or curved surface.

(5) The PLM includes a glare stop (179).

The sample side field of view is a distance that can be scanned by a focused beam of more than a predetermined intensity. The glare stop 179 may block ambient light incident on the PLM 170 around a sample.

The aberrations may include Seidel third order aberrations, first order chromatic aberration, color spherical aberration, color coma aberration, and color astigmatism for optical axis and stockpile points. The aberration was corrected for diffraction limit performance by using an error function in design. The top curvature aberration was corrected by introducing an upper curvature with an appropriate curvature.

5 are computer simulation results illustrating the performance of the PLM described with reference to FIG. 4.

For a pump beam (red) with a wavelength of 817 nm, the radius of the Airy disk is 0.71 micrometers. For a Stokes beam (blue) with a 1064 nm wavelength, the radius of the Airy disk is 0.93 micrometers.

Referring to FIG. 5, the longitudinal spherical aberration (LSA) has a maximum value of 0.24 micrometers in the pump beam. The longitudinal spherical aberration is about 1/3 or 1/4 of the radius of the Airy disk. The difference in focal length between the pump beam and the Stokes beam is small, 0.06 micrometers. That is, chromatic aberration is almost completely corrected. Also, the pump beam and the stokes beam are focused at one point.

The Astigmatic Field curvature (AFC), which represents the quality and chromatic aberration of wavelengths, is well calibrated to 0.29 micrometers.

6, A spot diagram of the PLM described in FIG. 4 is shown.

Spot diagrams indicate the quality (performance) of the overall image formation. All spots are placed in a circle of radius (0.4 micrometers) with respect to the on axis. It is also arranged in a circle of radius (0.64 micrometers) with respect to the off-axis. Thus, the optical device has a diffraction limit performance.

However, the positional difference between the spots of the pump beam (blue) and the stokes beam (red) is about 0.1 micrometer. Therefore, the position difference is a very small amount, and chromatic aberration is almost completely corrected. That is, the PLM can generate a CARS signal at one point in vivo due to optical performance.

7 illustrates a geometric optical relationship between an ALM and a PLM of an optical device according to another embodiment of the present invention.

Referring to FIG. 7, H is a first principle point and H 'is a second principle point. Equations 1 to 4 are derived from the geometric optical relationship created by the optical axis and the principal ray.

Where S is the distance between the common top surface and the glare stop 179, fa is the effective focal length of the ALM 160, D is the diameter of the aperture stop 169, and NAO is the PLM 170. Is the numerical side of the object side, and η is the common top surface height.

The designed PLM 170 provides, as parameters, the angle of incidence θ at the common top surface, the common top height η, and the object-side numerical aperture (NAO) of the PLM. The three parameters above Substituting the equation, the effective focal length fa of the ALM and the diameter D of the aperture stop are obtained. Thus, a total of five parameters are used. The chief ray passing through the center of the aperture stop 169 of the ALM 160 is refracted by the ALM 160, and then maintains the angle of incidence θ with respect to the optical axis, and ends of the common upper surface (PLM object). Side end).

The aperture stop 169 is necessary to limit the width of the input beam to maintain the sample side numerical aperture (NAS) from 0.5 to 0.7 with respect to water immersion.

FIG. 8 is a view for explaining an optical device that satisfies the condition obtained in FIG. 7.

Referring to FIG. 8, the ALM 160 satisfying Equations 1 to 4 and aberration includes an aperture stop 169. In addition, the ALM 160 includes eight or more lenses 161 to 168. In addition, the lenses 161 to 168 are flat or spherical.

9 shows a spot diagram of the ALM of FIG. 8.

Referring to FIG. 9, the ALM is completely corrected not only for the diffraction limit but also for chromatic aberration.

The pump beam (wavelength 817 nm) is blue and the Stokes beam (wavelength 1064 nm) is red.

10 illustrates optical characteristics when the PLM of FIG. 4 and the ALM of FIG. 7 are combined.

Referring to FIG. 10, the PLM and ALM are designed in an optimal state. However, if the PLM and ALM combine with each other, some inconsistency may occur. Because only 5 optical parameters were used to combine with the PLM. So, combining the PLM and ALM, the optimization design was carried out again. The spot diagram of the nosepiece is a performance that can be applied to a nosepiece for CARS imaging. That is, the nosepiece has diffraction limit performance for each pump beam and Stokes beam, and the focus of the pump beam and Stokes beam is almost coincident.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be implemented without departing from the spirit.

160: ALM
170: PLM
130: scanning unit
110: light source
150: detector
190: sample

Claims

A scanning unit providing a parallel beam for scanning;
An adapter lens module (ALM) providing the parallel beam to form focal trajectories on a common image plane (IIP); And
A probe lens module (PLM) capable of focusing the focal trajectories on a sample and delivering the sample to a sample upper surface and inserting the sample into the sample;
And an aperture stop disposed between the adapter lens module and the scanning unit so that the focal plane of the parallel beam is disposed on the common top surface.

The method according to claim 1,
The scanning unit scans pump beams and Stokes beams of different wavelengths, and the focused point of the sample outputs a Coherent Anti-Stokes Raman Scattering Signal (CARS) signal. Optical devices.

The method of claim 2,
The wavelength of the pump beam is 817 nm, and the wavelength of the stokes beam is 1064 nm.

The method of claim 2,
A dichroic mirror disposed in an optical path between the scanning unit and the probe lens module and selectively reflecting the coherent anti-Stokes Raman scattering signal passing through the probe lens module and the adapter lens module; And
A detector for detecting the coherent anti-stock Raman scattering signal selectively reflected through the dichroic mirror; Optical device further comprises at least one of.

The method according to claim 1,
The probe lens module has a length of 25 mm or more, and the optical aperture of the probe lens module (Clear Aperture) characterized in that the diameter of 2.6 mm or less.

The method according to claim 1,
The numerical aperture of the sample side of the probe lens module is 0.5 to 0.8 in consideration of water immersion.

The method according to claim 1,
The numerical aperture (numerical aperture) of the object side of the probe lens module is 0.04 to 0.06.

A scanning unit providing a parallel beam for scanning;
An adapter lens module (ALM) providing the parallel beam to form focal trajectories on a common image plane (IIP); And
A probe lens module (PLM) capable of focusing the focal trajectories on a sample and delivering the sample to an upper surface of the sample and inserting the sample into the sample;
The number of lenses of the probe lens module is at least eight, the optical device characterized in that consisting of a spherical surface and a plane.

The method according to claim 1,
The sample side field of view is within 0.22 mm.

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A scanning unit providing a parallel beam for scanning;
An adapter lens module (ALM) providing the parallel beam to form focal trajectories on a common image plane (IIP); And
A probe lens module (PLM) capable of focusing the focal trajectories on a sample and delivering the sample to an upper surface of the sample and inserting the sample into the sample;
And an aperture stop disposed between the adapter lens module and the scanning unit so that the focal plane of the parallel beam is disposed on the common upper surface.
The probe lens module includes a glare stop,
The probe lens module and the adapter lens module satisfy the following conditions,

Where S is the distance between the common top surface and the glare stop,
fa is the effective focal length of the adapter lens module,
D is the diameter of the aperture stop,
NAO is the object-side numerical diameter of the probe lens module, and
(eta) is a common image height.

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An optical device comprising an adapter lens module (ALM),
The adapter lens module is disposed between a scanning unit providing a scanning parallel beam and a focal locus focused on a sample, and a probe lens module (PLM) insertable into the sample, wherein the parallel beam is a common top surface. an adapter lens module (ALM) for providing the focal loci in the intermediate image plane;
And an aperture stop disposed between the adapter range module and the scanning unit so that the focal plane of the parallel beam is disposed on the common upper surface.
A principal ray passing through the center of the aperture stop is refracted by the adapter lens module and incident on the common image while maintaining a predetermined angle to the optical axis of the adapter lens module.

An optical device comprising an adapter lens module (ALM),
The adapter lens module is disposed between a scanning unit providing a scanning parallel beam and a focal locus focused on a sample, and a probe lens module (PLM) insertable into the sample, wherein the parallel beam is a common top surface. an adapter lens module (ALM) for providing the focal loci in the intermediate image plane;
The probe lens module includes a glare stop,
The probe lens module and the adapter lens module meet the following conditions,

An optical device comprising an adapter lens module (ALM),
The adapter lens module is disposed between a scanning unit providing a scanning parallel beam and a focal locus focused on a sample, and a probe lens module (PLM) insertable into the sample, wherein the parallel beam is a common top surface. an adapter lens module (ALM) for providing the focal loci in the intermediate image plane;
The adapter lens module (ALM) comprises at least eight lenses, wherein the lens is formed in a planar or spherical surface.

delete

An optical device comprising a probe lens module (PLM),
Focusing the sample on a sample by focusing the focal loci provided through a scanning unit providing a parallel beam for scanning and an adapter lens module (ALM) providing the parallel beam to form focal loci on a common image plane (IIP) Can be delivered to the top surface and inserted into the sample,
The probe lens module has a length of 25 mm or more, the diameter of a clear aperture of the probe lens module is 2.6 mm or less, and the numerical aperture of the sample side of the probe lens module is water-immersed ( 0.5 or more in consideration of water immersion, and the number of lenses of the probe lens module is at least eight, composed of curved or flat surfaces, and the sample side field of view is within 0.22 mm.