JP2015022233A - Optical resolution improving device and slide glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical resolution improving device and a slide glass, capable of more surely receiving diffraction light transmitted through an object to be measured.SOLUTION: A laser light source 10 emitting light is arranged opposite to an objective lens 11 and a sample S is convergently irradiated with the light emitted by the laser light source 10. The sample S is stably supported in a solution placed on a slide glass 72, while being covered with a cover glass 71. The slide glass 72 has a structure including a projection 72B having a hemispherical surface, in addition to a plate-like main body part 72A on which the sample S is placed.

Description

  The present invention relates to an optical resolution improving apparatus and a slide glass that realize measurement and observation of a surface state profile and a surface state of a cell or the like with an extremely high resolution by irradiation with a laser beam, and improve the resolution of an optical device such as a microscope. It is suitable for this.

  In order to measure and observe minute objects with high accuracy, two laser beams with different frequencies are made to interfere, a beat signal of the difference frequency is created, and the phase change of this beat signal is detected. Thus, it is conceivable to measure and observe the object to be measured.

  In Japanese Patent Application Laid-Open No. 59-214706 of Patent Document 1 below, two beams having different wavelengths are generated adjacent to each other using an acousto-optic device, and a phase change between these two beams is detected. A method for accumulating phase changes to obtain a surface profile is disclosed. However, in the technique of Patent Document 1, information in the beam profile cannot be extracted, and the resolution in the beam profile that is in the plane cannot be increased.

  On the other hand, a technique called a DPC (Differential Phase Contrast) method has been conventionally known. This is a technique that was first applied to an electron microscope by Dekkers and de Lang, and was later extended to an optical microscope by Sheppard and Wilson et al. This DPC method is a far field with respect to the electromagnetic wave irradiated to the sample, and is a result of interference between the zeroth-order diffracted light and the first-order diffracted light detected by detectors arranged symmetrically with respect to the irradiation axis of the electromagnetic wave. By obtaining the differential signal, the profile information of the sample is obtained. However, in this DPC method, if the spatial frequency becomes high, the 0th-order diffracted light and the 1st-order diffracted light cannot interfere with each other, and as a result, the spatial frequency is not reproduced, and measurement may not be possible.

  In other words, a conventional imaging microscope using electromagnetic waves could not exceed the resolution that is the limit of Abbe's theory. Therefore, it has been difficult to overcome the limitations due to the substantial wavelength used not only in the optical microscope but also in the electron microscope.

JP 59-214706 A

Here, the OTF characteristic of the objective lens in the conventional microscope using the imaging optical system will be described below.
In a conventional microscope using an imaging optical system, the first-order diffracted light component and the zero-order diffracted light component of the object to be measured captured by the objective lens interfere with each other to form an image. If the first-order diffracted light is not incident on the aperture, the spatial frequency is not reproduced. On the other hand, since the diffraction angle of the first-order diffracted light gradually increases from a low frequency to a high frequency, the amount of the first-order diffracted light input to the objective lens decreases. As a result, the frequency at which the first-order diffracted light is not input is cut off, and the degree of modulation gradually decreases in the middle from the low frequency to the high frequency.

  The above is the OTF characteristic of the objective lens. Therefore, in the imaging system, the first-order diffracted light input to the objective lens is naturally limited, so the resolution is naturally limited in relation to the spatial frequency of the symmetrical object to be reproduced. There will be.

The above qualitative explanation is quantified and explained in detail below.
As shown in FIG. 13, it is assumed that a parallel light beam is incident on the objective lens 11 having an aperture radius of a and a focal length of f. In FIG. 13, the irradiation optical axis is represented by the optical axis L0, and the inclined optical axis inclined by the angle Θ with respect to the optical axis L0 is represented by the optical axis L1. A microscope using normal imaging is a transmission type in which the light beam passes through the sample S as shown in FIG. 13, but may be considered as a reflection type in which the light beam is folded back on the sample S. In order to simplify the formula, it is treated as a one-dimensional opening.

For simplicity, it is assumed that the sample S has a sine wave shape having a height h and a pitch d. That is, the optical phase θ is expressed by the following formula.
θ = 2π (h / λ) sin (2πx / d) (1) Equation The amplitude E of the light diffracted from the sample S is the Fourier of the equation (1) on the plane separated by the focal length f. Since it is given as a convolution of the transformation and the aperture of the lens, it is expressed as follows. However, the Bessel function that is the Fourier transform of the phase of equation (1) is assumed to be ± 1st order.

Here, the Fourier transform of equation (2) contributes to imaging.
Accordingly, the intensity I is expressed by the following equation (3).

  The meaning of this equation is that information with a pitch smaller than d = λf / 2a = 0.5λ / NA is lost. This means that the beam diameter of the rectangular aperture (sinc (ka) = 0 The dark ring radius w is equal to w = 0.5λ / NA because ka = π is satisfied. Further, even when d> 0.5λ / NA, the smaller the d is, the lower the modulation degree is. If the relationship between the spatial frequency of 1 / d and the modulation factor is shown, this is MTF.

  As described above, in a normal imaging optical system, the limit of the spatial frequency reproduced by the NA of the objective lens 11 is necessarily d = λf / 2a = 0.5λ / NA, which is smaller than this value. Things will not be reproduced in any way.

  On the other hand, the diffraction of the first-order diffracted light has the following problems. In other words, when a measurement object is observed using a conventional general slide glass, not only the front side of this slide glass but also the back side is flat, so that it passes through the measurement object and enters the slide glass. If the incident angle of the first-order diffracted light on the air side at the boundary between the slide glass and air is greater than the critical angle, it cannot be totally reflected and taken out.

Below, the problem of the slide glass of a prior art is demonstrated in detail.
As shown in FIG. 14, a parallel light beam enters the lens 11 from the laser light source 10, is focused by the lens 11, and the light beam is irradiated to the sample S that is an object to be measured on the slide glass 172. It is assumed that the diffracted light diffracted by the sample S is incident.
14 and 15, the irradiation optical axis of the laser light source 10 that is perpendicularly incident on the slide glass 172 is represented by an optical axis L0. In FIG. 15, the optical axis of the first-order diffracted light transmitted through the slide glass 172 is represented by an optical axis L1, and the angle of the optical axis L1 with respect to the optical axis L0 is α1. The refractive index of the slide glass 172 is n.
From the above, when the incident angle of the first-order diffracted light emitted from the inside of the slide glass 172 to the outside of the slide glass 172 via the boundary surface B is α1, and the refraction angle is α2, the following equation is obtained according to the law of refraction. Holds.
nsinα1 = sinα2

Here, when the incident angle α1 is α1 <90 ° and the refraction angle α2 is 90 °, the incident angle α1 becomes a critical angle, and the first-order diffracted light incident on the boundary surface B from the inside of the slide glass 172 is greater than the critical angle. Are all reflected and are not emitted outside the slide glass 172. For example, the first-order diffracted light at the critical angle is represented by a light beam LX.
From the above formula, the critical angle is expressed as sin α1 = 1 / n, and it is necessary to consider the wavelength and wavelength dispersion of the laser beam to be used. To be simple, if n = 1.52, α1 = 41.14 °. From the above, the first-order diffracted light having the included angle α3, which is the angle formed by the optical axis L1 and the boundary surface B, of 48.86 ° or less cannot be extracted from the slide glass 172.

  Therefore, since the first-order diffracted light input to the objective lens is naturally limited due to the influence of the slide glass, the resolution is naturally limited in relation to the spatial frequency of the measurement object to be reproduced.

  Accordingly, an object of the present invention is to provide an optical resolution improving apparatus and a slide glass that can receive diffracted light transmitted through a measurement object more reliably.

In order to achieve the above object, an optical resolution improving apparatus according to claim 1 includes a light source that irradiates a measurement object with a light beam,
A light receiving element that receives light transmitted through the measurement object;
A slide disposed between the light receiving element and the light source, the measurement object can be placed on the light source side surface, and a convex portion having a curved surface is provided on the light receiving element side surface Glass,
including.

The operation of the optical resolution improving apparatus according to claim 1 will be described below.
According to this claim, the light beam is irradiated from the light source onto the measurement object installed on the slide glass, and the light receiving element receives the light transmitted through the measurement object. At this time, a convex portion having a curved surface is provided on the surface of the slide glass disposed between the light receiving element and the light source on the light receiving element side.
Therefore, the diffracted light generated as it passes through the measurement object is incident on the outside from the convex portion having a curved surface, so that the incident angle is reduced and the glass slide is not totally reflected. Is injected from.

  As described above, according to the optical resolution improving apparatus of the present invention, the light receiving element can acquire higher-order diffracted light among the diffracted light transmitted through the measurement object. As a result, it is possible to acquire a spatial frequency that cannot be acquired with the reproduction spatial frequency of a normal imaging optical system, and to improve the resolution of the optical system.

The operation of the optical resolution improving apparatus according to claim 2 will be described below.
The optical resolution improving apparatus according to the present invention has the same configuration as that of the first aspect, but the light receiving element further includes a first light receiving element and a pair of second light receiving elements, and the slide glass Is an optical resolution improving device arranged between the light receiving element and the light source,
A first lens that is located on the irradiation optical axis of the luminous flux and converts the luminous flux that has passed through the measurement object and the slide glass into a parallel luminous flux;
A first light-receiving element having at least two divided light-receiving elements that respectively receive light on each side portion across the irradiation optical axis of transmitted light that has passed through the first lens;
A light beam that is located on an inclined optical axis that has an inclination on each side on which the divided light receiving elements of the first light receiving element receive light with respect to the irradiation optical axis and that has passed through the measurement object and the slide glass. A pair of second lenses each having a parallel luminous flux;
An optical element that causes interference between the light beam emitted from the first lens and the light beam emitted from each of the second lenses;
A pair of second light receiving elements for receiving each light beam interfered by the optical element;
An output sum difference detection unit for detecting an output sum or output difference between the divided light receiving elements located across the irradiation optical axis of the first light receiving element and an output sum or output difference between the pair of second light receiving elements; ,
including.
That is, a first lens and a second lens having an optical axis are arranged between the principal ray axes of the 0th-order diffracted light and the 1st-order diffracted light, and the 0th-order diffracted light or the 1st-order diffracted light diffracted by the measurement object is parallel. The light is converted into a light beam, the image is inverted with an optical element such as a Dove prism for one of the lights, and is further parallel-shifted with an optical element such as a rhomboid prism so that the 0th-order diffracted light and the 1st-order diffracted light overlap. It is conceivable that the 0th-order diffracted light and the 1st-order diffracted light interfere with each other.
By performing this in two systems between the 1st-order diffracted light and the 0th-order diffracted light and between the -1st-order diffracted light and the 0th-order diffracted light, the sum signal and the difference signal by the two types of light receiving elements arranged in the far field are further increased It will have large spatial frequency information, and resolution will be further improved substantially.

The operation of the optical resolution improving apparatus according to claim 3 will be described below.
The optical resolution improving apparatus according to the present invention has the same configuration as that of the first aspect, but the light receiving element further includes a plurality of light receiving elements and a plurality of second light receiving elements, and the slide glass includes An optical resolution improving apparatus disposed between these light receiving elements and the light source,
A lens that is positioned on an inclined optical axis that is inclined with respect to the irradiation optical axis of the convergent irradiation, and that makes the light beam transmitted through the measurement object and the slide glass a parallel light beam;
A first light beam that passes through a portion of the lens near the irradiation optical axis of a light beam incident on the lens and a second light beam that passes through one half of the lens far from the irradiation optical axis interfere with each other. An optical element of
A plurality of first light receiving elements for respectively detecting light beams interfered by the first optical element;
A second optical element disposed in a direction opposite to the first optical element with respect to the inclined optical axis, and causing the first light beam and the second light beam to interfere with each other;
A plurality of second light receiving elements for respectively detecting light beams interfered by the second optical element;
An output sum / difference detector for detecting an output value of a sum or a difference between an arbitrary received light output of the plurality of first light receiving elements and an arbitrary received light output of the plurality of second light receiving elements;
including.
Thus, similarly to claim 2, two types of light receiving elements arranged in the far field are performed by two systems between the 1st order diffracted light and the 0th order diffracted light and between the −1st order diffracted light and the 0th order diffracted light. As a result, the sum signal and the difference signal due to the have larger spatial frequency information, and the resolution is further improved substantially.

The operation of the optical resolution improving apparatus according to claim 4 will be described below.
The optical resolution improving apparatus according to the present invention has the same configuration as that of the first to third aspects, but further, the surface of the convex portion is spherical, and on the surface of the slide glass on the light source side. The center of curvature of the convex portion is located at
As a result, the diffracted light that has passed through the measurement object is emitted perpendicularly to the outside of the slide glass through the spherical surface of the convex portion, so that at the boundary surface between the slide glass and the external air Diffracted light can be more reliably extracted from the slide glass without total reflection.

The operation of the optical resolution improving apparatus according to claim 5 will be described below.
The optical resolution improving apparatus according to the present invention has the same configuration as that of the first to third aspects, but the surface of the convex portion is a lens surface, and the surface of the convex portion is formed in the slide glass. The focal position is located.
Therefore, the diffracted light from the measurement object is emitted from the slide glass with the emission direction narrowed with respect to the light receiving element. For this reason, even for diffracted light having a larger diffraction angle, it is possible to acquire diffracted light with a light receiving element of the same size. That is, information with a higher spatial frequency can be acquired.
Moreover, if the curvature of the surface of the convex portion is set to a curvature that is in the vicinity of the measurement object, the emitted light travels straight from the slide glass as it is, and a Fourier transform of the measurement object is obtained on the light receiving element. It will be.

The operation of the optical resolution improving apparatus according to claim 6 will be described below.
The optical resolution improving apparatus according to the present invention has the same configuration as that of the first to fifth aspects, but the refractive index of the member constituting the convex portion constitutes another part of the slide glass. It is higher than the refractive index of the member.
Therefore, when the diffracted light is incident on the convex portion from the main body portion which is the other portion of the slide glass, the diffracted light is made to tend to be focused and received by the light receiving element. For this reason, similarly to the third aspect, information having a higher spatial frequency can be acquired.

The operation of the optical resolution improving apparatus according to claim 7 will be described below.
The optical resolution improving apparatus according to the present invention has the same configuration as that of the first to sixth aspects, but is further provided with a plurality of the convex portions on the light source side of the slide glass facing the convex portions. A concave portion in which a measurement object can be placed is provided at the position.
Accordingly, the measurement objects are installed in the plurality of recesses, and the respective measurement objects can be observed sequentially, so that efficient observation can be performed. For example, cells and the like can be cultured in each recess, and it becomes possible to easily observe changes over time of many cells.

  In order to achieve the above object, the slide glass according to claim 8 is a plate-like slide glass used in an optical instrument in which a measurement object can be installed and which observes the measurement object, A convex portion having a curved surface is formed on one surface so as to be formed integrally with another portion or bonded to the other portion.

The operation of the slide glass according to claim 8 will be described below.
According to this claim, the convex part having the curved surface is formed integrally with the other part on one surface of the plate-shaped slide glass on which the measurement object can be installed, or other Adhering to the part is provided. For this reason, when used in an optical instrument for observing a measurement object, diffracted light generated as it passes through the measurement object is incident to the outside from a convex portion having a curved surface. Thus, the incident angle is reduced and the light is emitted from the slide glass without being totally reflected.
As described above, according to the slide glass according to the present invention, the light receiving element can acquire higher-order diffracted light among the diffracted light transmitted through the measurement object. As a result, it is possible to acquire a spatial frequency that cannot be acquired with the reproduction spatial frequency of a normal imaging optical system, and to improve the resolution of the optical system.

  According to the present invention, there is an excellent effect that an optical resolution improving device and a slide glass that can receive diffracted light transmitted through a measurement object more reliably are provided.

It is the schematic showing the optical system which showed Example 1 which concerns on the optical resolution improvement apparatus and slide glass of this invention. It is an enlarged view of the principal part of FIG. It is a block diagram showing the transmission optical system in DPC method. It is a block diagram showing the transmission optical system which combined DPC method and heterodyne method. It is the schematic showing the optical system which showed Example 2 which concerns on the optical resolution improvement apparatus of this invention. It is the schematic showing the optical system which showed Example 3 which concerns on the optical resolution improvement apparatus of this invention. It is the schematic showing the optical system which showed Example 4 which concerns on the optical resolution improvement apparatus of this invention. It is the schematic showing the optical system which showed Example 5 which concerns on the optical resolution improvement apparatus of this invention. It is the schematic showing the optical system which showed Example 6 which concerns on the optical resolution improvement apparatus and slide glass of this invention. It is the schematic showing the optical system which showed Example 7 which concerns on the optical resolution improvement apparatus and slide glass of this invention. It is the schematic showing the optical system which showed Example 8 which concerns on the optical resolution improvement apparatus and slide glass of this invention. It is an AA arrow line drawing of FIG. It is a principle figure explaining the principle of a normal image formation optical system. It is a principle figure explaining the principle of reflection of a normal slide glass. It is a principal part enlarged view of FIG.

  Embodiments of an optical resolution improving apparatus and a slide glass according to the present invention will be described below in detail with reference to the drawings.

Embodiment 1 of an optical resolution improving apparatus and a slide glass according to the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic diagram showing the configuration of an optical resolution improving apparatus of this embodiment, which is a kind of optical equipment. As shown in FIG. 1, a laser light source 10 that is a light source for irradiating light is disposed facing an objective lens 11 via an optical device (not shown), and the light emitted by the laser light source 10 is transmitted through The sample S, which is a measurement object, is focused and irradiated. However, this sample S is stably supported in the aqueous solution E placed on the slide glass 72 while being covered with the cover glass 71 shown in FIGS. 1 and 2. In this embodiment, the slide glass 72 is used. In addition to the plate-like main body 72A on which the sample S is placed, a convex portion 72B having a hemispherical surface is provided.

  And the main-body part 72A of this slide glass 72 has the upper surface 72C by the side of the laser light source 10 on which the sample S is mounted, as shown in FIG. 2, and the lower surface 72D provided with the convex part 72B, The center of curvature P of the surface of the convex portion 72B exists at a position on the upper surface 72C on which the sample S is placed. That is, the diffracted light that has passed through the sample S and entered the slide glass 72 from the upper surface 72C is emitted from the slide glass 72 at the same angle without being totally reflected from the convex portion 72B having the spherical surface. Become so.

  On the optical axis L0 that is the irradiation optical axis of the convergent irradiation of the laser light source 10, a lens 15 that is a first lens that is a convex lens is located, and passes through the sample S and passes through the slide glass 72. The lens 15 converts the light beam emitted from the slide glass 72 into a parallel light beam.

  On the optical axis L0 below the lens 15, two first beam splitters 12A and 12B for respectively dividing the parallel light beams emitted from the lens 15 into left and right are continuously arranged, and below this, A first light receiving element 6 for receiving this light is located. However, the first light receiving element 6 is composed of two divided light receiving elements 6A and 6B positioned with the optical axis L0 interposed therebetween, and the right divided light receiving element 6A includes the transmitted light from the lens 15. The right side portion of the optical axis L0 is received, and the left side divided light receiving element 6B receives the left side portion of the optical axis L0 of the transmitted light from the lens 15.

  A lens 16 that is a second lens that is a convex lens is positioned on the optical axis L1 that is the optical axis of the first-order diffracted light that is inclined on the right side of FIG. 1 with respect to the optical axis L0. The lens 16 uses the light beam emitted from the sample S as a parallel light beam. A reflecting mirror 18 for reflecting the parallel light beam is disposed on the optical axis L1, and a second beam splitter 13 is located below the reflecting mirror 18. For this reason, the reflecting mirror 18 disposed between the lens 16 and the second beam splitter 13 reflects the emitted light from the lens 16 toward the second beam splitter 13. In addition, a second light receiving element group 4 including a plurality of divided light receiving elements is located below the second beam splitter 13.

  Further, the light beam obtained by splitting the upper first beam splitter 12A out of the two first beam splitters 12A and 12B is sent to the second beam splitter 13 side. Therefore, the light beam emitted from the lens 15 and the light beam emitted from the lens 16 are caused to interfere with each other by the second beam splitter 13 so that the second light receiving element group 4 receives the light beam.

  On the other hand, the lens 17, the reflecting mirror 19, the second beam splitter 14, and the second light receiving element group 5 having the same configuration as described above are arranged symmetrically with respect to the irradiation optical axis L0 and also on the left side of FIG. Has been. As described above, the two first beam splitters 12A and 12B and the left and right second beam splitters 13 and 14 cause the light beams emitted from the lens 15 and the light beams emitted from the lenses 16 and 17 to interfere with each other.

  Further, the divided light receiving elements 6A and 6B and the light receiving element groups 4 and 5 described above are connected to a comparator 33 for comparing signals from the light receiving elements 6A and 6B and the light receiving element groups 4 and 5, respectively. The comparator 33 is connected to a data processing unit 34 that finally processes the data to obtain the profile of the sample S and the like. For this reason, the comparator 33 and the data processing unit 34 include the output sum and output difference between the divided light receiving elements 6A and 6B of the first light receiving element 6 located across the optical axis L0, and a pair of second light receiving elements. An output sum difference detection unit that detects an output sum and an output difference between the groups 4 and 5 is used.

  From the above, the light converged by the objective lens 11 shown in FIG. 1 forms a spot on the sample S that is a measurement object placed on the slide glass 72 while being covered with the cover glass 71. The spot ideally has a diffraction limit diameter, and the spatial frequency information of the pattern of the sample S within the spot diameter is diffracted as transmitted light.

On the other hand, in the present embodiment, as described above, the convex portion 72B is provided on the lower surface side of the slide glass 72. Here, the radius r of the surface of the convex portion 72B shown in FIG. 2 which is an enlarged view of a part of FIG. 1 is obtained from the following equation. In the following formula, t is the thickness of the slide glass 72, d is the diameter of the observation range set on the slide glass 72, and α3 is transmitted from the outside of the slide glass 72 through the sample S as in FIG. This is the included angle between the first-order diffracted light incident on the slide glass 72 and the boundary surface.
r = (t / tanα3) + d / 2

  In this embodiment, t is 1.2 mm as in a general slide glass, and d is 0.5 mm, which is a diameter sufficient for observing cells and the like. Here, when trying to extract the first order diffracted light with the included angle α3 formed by the first order diffracted light and the boundary surface up to 10 °, t / tan α3 is about 6.8 mm and d / 2 is 0.25 mm. The radius r of the convex portion 72B is about 7.1 mm from the above formula. The surface shape of the convex portion 72B is not limited to a spherical shape, and may be a general curved surface that allows the first-order diffracted light having a constant high spatial frequency to be extracted outside without being totally reflected. .

  Here, in consideration of the first-order diffracted light having the spatial frequency that the sample S has and having high spatial frequency that is not incident on the lens 15, the lens 15 has zero-order diffracted light transmitted through the sample S and a space lower than the spatial frequency. Frequency component light is incident. Thus, with the lens 15 alone, the pattern of the sample S can be reproduced up to the cutoff frequency of the lens 15.

  However, the light of spatial frequency that is not incident on the lens 15 is cut, and the image information is lost. Therefore, as shown in FIG. 1, the lens 16 and the lens 17 are located at mutually target positions with respect to the optical axis L0 of the 0th-order diffracted light and have a certain inclination angle. The inclination angles of the optical axes L1 and L2 of the lens 16 and the lens 17 with respect to the optical axis L0 of the 0th-order diffracted light are set to be comparable to the spatial frequency at which the contrast of the sample S is maximized.

  That is, the light beam on the optical axis L1 of the lens 16 is folded by the reflecting mirror 18 and synthesized by the beam splitter 13 with the light beam on the optical axis L0 of the 0th-order diffracted light separated by the beam splitter 12A. The synthesized light itself is guided to the light receiving element group 4. Therefore, the light receiving element group 4 receives light by causing the 0th order diffracted light and the 1st order diffracted light emitted from the lens 16 to interfere with each other. This is because the light beam having the highest contrast is a light beam having a spatial frequency coinciding with the optical axis L1 of the lens 16.

  When considering a similar optical system in the opposite direction to the optical axis L0 of the above-described optical system and the 0th-order diffracted light, the light beam on the optical axis L2 that is the inclined optical axis of the lens 17 is folded back by the reflecting mirror 19, The light beam on the optical axis L2 of the lens 17 is combined by the beam splitter 14 with the light beam on the optical axis L0 of the 0th-order diffracted light that is turned back by the beam splitter 12B through the beam splitter 12A. The synthesized light itself is guided to the light receiving element group 5. The light receiving element group 5 receives light while interfering with the 0th order diffracted light and the −1st order diffracted light emitted from the lens 17.

  Here, the light receiving element group 4 includes a plurality of divided light receiving elements, and each divided light receiving element acquires interference fringe intensity obtained by sampling the interference fringes interfered by the 0th order diffracted light and the 1st order diffracted light at an appropriate pitch. In other words, if the optical axis L0 of the 0th-order diffracted light and the optical axis L1 of the 1st-order diffracted light have no inclination, the interference intensity is uniform within the light beam, but if there is a slight inclination, interference with a uniform pitch occurs. This is because stripes are produced. Since the pitch of the interference fringes depends on the emission angle of the first-order diffracted light, it reflects the spatial frequency incident on the lens 16.

  The light receiving element group 5 also includes a plurality of divided light receiving elements, and each divided light receiving element acquires interference fringe intensity obtained by sampling the interference fringes interfered by the 0th order diffracted light and the −1st order diffracted light at an appropriate pitch. Works as well.

  Accordingly, the light receiving element groups 4 and 5 are arranged in a form constituted by a plurality of divided light receiving elements, respectively, and information reflecting the spatial frequency can be acquired. By acquiring the output of the difference between the light receiving elements that have acquired substantially the corresponding spatial frequencies of the light receiving element groups 4 and 5, higher spatial frequency information can be acquired.

  The above is particularly effective in the optical system of the DPC method and the optical system combining the DPC method and the heterodyne method proposed by the inventors.

The point that the substantial spatial frequency that can be obtained by the optical system can be increased will be clarified below. However, in order to simplify the description, it is assumed that the sample S has a sine wave shape having a height h and a pitch d. That is, the optical phase θ is expressed by the following formula.
θ = 2πh / λsin (2πx / d + θ0) (4)

The amplitude E of the light diffracted from the sample S is given as a convolution of the Fourier transform of the equation (4) and the lens aperture on the surface separated by f, and is expressed as follows. However, the Bessel function that is the Fourier transform of the phase in equation (4) is assumed to be ± 1st order. Here, E ₀ and E ₁ are complex amplitude distributions through the lens 15 and the lens 16 into which the 0th-order diffracted light and the 1st-order diffracted light are incident, respectively. Each is expressed by equations (5) and (6).

Similarly, when E ₋₁ is a complex amplitude distribution that is an amplitude distribution through the lens 17 on which the −1st order diffracted light is incident, the following equation (7) is obtained.

From the equation (5) representing the complex amplitude distribution of the 0th-order diffracted light and the equation (6) representing the complex amplitude distribution of the 1st-order diffracted light, the light flux of the lens 15 and the light flux of the lens 16 are synthesized by the beam splitters 12A and 13. The intensity I ₁ on the light receiving element group 4 obtained as a result of interference on the light receiving element group 4 is expressed by the following equation.

Similarly, from the equation (5) representing the complex amplitude distribution of the 0th-order diffracted light and the equation (7) representing the complex amplitude distribution of the −1st-order diffracted light, the light beams of the lens 15 and the lens 17 are converted by the beam splitters 14 and 12B. The intensity I ₂ on the light receiving element group 5 obtained as a result of combining and causing interference on the light receiving element group 5 is expressed by the following equation.

However, the intensity I ₁ and the intensity I ₂ are assumed to have substantially no optical path difference between the 0th order diffracted light and the ± 1st order diffracted light for simplicity. Thus, the difference output between the light receiving element group 4 and the light receiving element group 5 is expressed by the following equation.

Here, the light receiving element group made up of an appropriate number of divided light receiving elements without using a single light receiving element has a correspondence relationship between the light receiving elements and the spatial frequency. This is because the analysis taking into account the distribution of the spatial frequency components to be taken into consideration can be performed.
If the 0th-order diffracted light and the 1st-order diffracted light do not interfere with each other, the intensity of the ± 1st-order diffracted light is expressed by the following equation, and becomes 0 when the difference output is acquired.

  Even if the sum output is acquired, the phase information θ0 is completely lost, and only information on whether or not the spatial frequency exists in the sample S is obtained, and information desired to be acquired such as profile information is acquired. It is not possible.

  Hereinafter, an optical system of the DPC method which is effective by specifically applying the above optical system and an optical system combining the DPC method and the heterodyne method will be described. Here, FIG. 3 shows a block diagram of a transmission optical system in the DPC method.

  First, as shown in FIG. 3, the light beam from the laser light source 21 is converted into a parallel light beam by the collimator lens 22 and is incident on the two-dimensional scanning device 26. The two-dimensional scanning device 26 is a device that scans light on a surface, and includes a MEMS, a galvanometer mirror, a resonant mirror, and the like.

  The parallel light flux is incident on the objective lens 31 through the pupil transmission lens system 30 for transmitting the pupil position of the two-dimensional scanning device 26 to the pupil position of the objective lens 31 and then converges on the sample S. The light converged on the sample S becomes transmitted light and enters the light receiving element 29. The light receiving element 29 is disposed at a position substantially becoming a far field from the sample S, and is a light receiving element that is divided at least into two symmetrically with respect to the optical axis L.

  As a result, the parallel light beam on the optical axis L is separated into 0th order diffracted light and ± 1st order diffracted light by the refractive index distribution and unevenness of the sample S, and these separated lights are received by the light receiving element 29 while interfering with each other. The Along with this, the refractive index distribution and unevenness information of the sample S are converted in a photoelectric conversion unit (not shown) in the light receiving element 29 based on interference information between the 0th-order diffracted light and the ± 1st-order diffracted light. At this time, the above information of the sample S is reflected in the difference output between the two light receiving elements of the target light receiving element 29 with respect to the optical axis L. In this way, when obtaining a difference output, it may be performed between adjacent light receiving elements across a boundary line.

  However, if only the sum output of a plurality of light receiving elements is used, the same can be realized by using substantially one light receiving element. In particular, the sum output is effective when the sample S has an intensity pattern with different absorptance and reflectance. For example, this is a case where the sample S is stained with cells.

Also in the transmission optical system in the DPC method shown in FIG. 3, the slide glass 72 having the convex portion 72B having the hemispherical surface shown in FIGS. 1 and 2 is similarly used. However, in FIG. 3, the diffracted light is directly incident on the light receiving element 29 without using the members 15, 16, 17 and the beam splitters 12 A, 12 B, 13, 14 shown in FIG. .
Accordingly, similarly to the above, the diffracted light that has passed through the sample S and entered the slide glass 72 from the upper surface 72a is not totally reflected from the convex portion 72B having the spherical surface, and remains at the same angle. Is emitted from the slide glass 72 and is incident on the light receiving element 29.

Next, FIG. 4 shows an optical system combining the DPC method and the heterodyne method proposed by the inventors, which will be described below. Here, FIG. 4 shows a block diagram of a transmission optical system combining these methods.
This optical system is different from the optical system shown in FIG. 3 in that two light beams that are very close to each other are generated by the acoustooptic device 23 and irradiated on the sample S as shown in FIG.

  Specifically, as shown in FIG. 4, a collimator is provided between a laser light source 21 from which laser light is emitted and an acousto-optic device (AOD) 23 to which operation is controlled by connecting an AOD driver 24. A lens 22 is arranged. In addition, the acoustooptic device 23 includes a pupil transmission magnifying lens system 25 composed of two groups of lenses, a beam splitter 27 that separates and emits input laser light, and two-dimensionally scans the input laser light 2. The dimension scanning device 26 is arranged in order.

  Further, adjacent to the beam splitter 27, a pupil transmission lens system 30 comprising two groups of lenses is located, and an objective lens 31 is arranged next to the sample S so as to face it. That is, these members are arranged along the optical axis L. On the other hand, a light receiving element 28 that is an optical sensor is disposed at a position that is orthogonal to the direction in which the optical axis L passes and that is adjacent to the right of the beam splitter 27. A light receiving element 29 which is also an optical sensor is disposed on the lower side which is the back side of the sample S. The light receiving elements 28 and 29 are connected to a comparator 33 that compares signals from the light receiving elements 28 and 29, respectively, and the comparator 33 finally processes the data to obtain the profile of the sample S, etc. It is connected to the processing unit 34.

  Accordingly, the two DSB-modulated signals having the carrier frequency fc and the modulation frequency fm are input from the outside to the acoustooptic device 23 via the AOD driver 24, thereby creating these two light beams that are very close to each other. it can. The light beams emitted in two directions that are very close to each other are transmitted through a pupil transmission lens system 25 that transmits the substantial pupil position of the acoustooptic device 23 to the pupil position of the two-dimensional scanning device 26, and two-dimensionally scanning light on the surface. The light is incident on the objective lens 31 through the pupil transmission lens system 30 for transmitting the pupil position of the scanning device 26 and the two-dimensional scanning device 26 to the pupil of the objective lens 31.

  As a result, the light beam converged by the objective lens 31 scans the sample S on the surface as two very close spots. Since these two spots become two signals of frequency fc + fm and frequency fc−fm, by performing heterodyne detection on these signals, a signal reflecting unevenness information and refractive index distribution of sample S can be obtained.

  In this embodiment, in order to perform heterodyne detection, a part of the irradiated modulation signal is extracted by the beam splitter 27, a reference signal is obtained by the light receiving element 28, and this reference signal and the light receiving element 29 divided into two are detected. The differential output is obtained from the received signal, the phase difference information and the intensity information are acquired by the comparator 33 and sent to the data processing unit 34. The data processing unit 34 displays the information acquired together with the scanning information as an image or data form on a display or stores it as data in a memory.

  However, the light receiving element 28 is not necessarily required, and may be compared with a signal output to the acoustooptic element 23, that is, a signal itself applied to the acoustooptic element 23. In this case, a delay occurs due to a circuit system, an acoustooptic device, or the like, but if it is corrected in advance, it does not have a great influence on the phase difference detection.

  In addition, two very close spot lights that scan the surface of the sample S on the surface are lights having different frequencies from each other. However, in practice, an enlargement optical system such as the pupil transfer lens systems 25 and 30 is used. This makes it possible to make the spot very close even at a high frequency. Thus, high-speed information acquisition can be performed by high-speed scanning.

  Note that the slide glass 72 of this embodiment (not shown in this embodiment) can be adopted even with an optical system that combines the DPC method and the heterodyne method shown in FIG. Accordingly, diffracted light that has passed through the sample S (not shown) and entered the slide glass 72 from the upper surface 72a slides at the same angle without being totally reflected from the convex portion 72B having the spherical surface. The light is emitted from the glass 72 and is incident on the light receiving element 29 shown in FIG.

  On the other hand, the two lights obtained in this way can have a very low degree of separation by the above-described method, and are substantially the same as the information scanned with one beam. On the other hand, the DPC method described above is a method of scanning with one beam and obtaining a differential output of at least two divided light receiving elements arranged in the far field.

  In other words, compared to the DPC method, in the method further using the present heterodyne method, the phase change and the intensity change can be detected with high accuracy by performing the heterodyne detection, and the light received by the light receiving element 29 is reduced. Even if it is very weak, it can be detected with high accuracy by increasing the gain of the detection circuit system, and since the detected signal is only the modulation signal, it is not affected by disturbance light. High-precision detection can be performed.

  Further, by using the optical system shown in FIG. 1 for the light receiving element portion of the optical system as described above, information with a higher spatial frequency, that is, a significant improvement in lateral resolution can be achieved. Further, the light beam irradiating the sample S is made into a parallel light beam, the lenses 15, 16, and 17 shown in FIG. 1 are omitted, and other optical systems are made the same as in the above embodiment, thereby improving the optical resolution with respect to the parallel light beam system. It can also be a device.

  In the following examples, the light receiving element part of the following example may be applied to the light receiving element part of the optical system of the DPC method and the light receiving element part of the optical system combining the DPC method and the heterodyne method. Description of optical systems other than the light receiving element system is omitted.

In the present embodiment, the lens is installed inclined with respect to the optical axis L0 of the 0th-order diffracted light. As a result, not only a part of the 0th-order diffracted light but also a part of the 1st-order diffracted light having a higher spatial frequency compared to the case where the same lens is used can be taken. Interference between the folded light and the first-order diffracted light is realized.
In this embodiment, as shown in FIG. 5, a parallel light beam enters the objective lens 11, converges on the sample S, and diffracted light transmitted through the sample S exits from the slide glass 72 (not shown in this embodiment). The process is the same as that shown in FIG. However, in this embodiment, a part of the 0th order diffracted light and a part of the 1st order diffracted light transmitted through the sample S are optical axes having an intermediate inclination angle between the 0th order diffracted light and the 1st order diffracted light. The lens 36 is tilted by L3. Then, the light beams are interfered with each other by shifting and superimposing the light beams of the first-order diffracted light and the partial 0-order diffracted light using a rhomboid prism 39.

  One surface of the rhomboid prism 39 is a semi-transparent mirror 39A, and the surface opposite to the semi-transparent mirror 39A is a semi-transparent mirror 39B, and light receiving elements 40, 41, and 42 that receive light passing through the respective surfaces are disposed. Here, the light receiving element 40 and the light receiving element 41 reflect the interference result between part of the 0th order diffracted light and part of the 1st order diffracted light, respectively, and the light receiving element 42 includes part of the 0th order diffracted light of the lens 36. The interference result of the low spatial frequency 1st-order diffracted light and a part of the 0th-order diffracted light that is diffracted in the region is reflected.

The result of interference between the 0th-order diffracted light and the 1st-order diffracted light will be described with the following formula.
First, although not shown in FIG. 5, an optical system similar to the optical system shown in FIG. 5 is also arranged for the −1st order diffracted light so as to be symmetrical with the optical axis L0 of the 0th order diffracted light. It is considered as follows when the output difference of each corresponding light receiving element is acquired. In order to simplify the explanation, if the sample S has a sine wave shape with a height d and a pitch d, the optical phase θ is expressed by the following equation.

  θ = 2πh / λsin (2πx / d + θ0) (4)

The amplitude E of the light diffracted from the sample S is given as a convolution of the Fourier transform of the equation (4) and the lens aperture on a plane separated by the focal length f, and is expressed as follows.
However, the Bessel function that is the Fourier transform of the phase in equation (4) is assumed to be ± 1st order. Further, as shown in FIG. 5, the optical axis L3 is inclined by an angle ξ corresponding to approximately sin ⁻¹ (NA) of the lens. At this time, the direction perpendicular to the optical axis L3 is taken as the y-axis, and the center position of the first-order diffracted light corresponding to the spatial frequency 1 / d in the equation (1) is taken as Y1.
At this time, if the optical axis L3 is tilted by an angle ξ with reference to the above equation (2), the center of the zero-order diffracted light of equation (2) is shifted by a, and the central axis of the first-order diffracted light is y1. The complex amplitude distribution E ₁ is given by the following equation (8).

  Similarly, for the −1st order diffracted light in the optical system symmetrical to the 1st order diffracted light with respect to the optical axis L0 of the 0th order diffracted light, the following equation (9) is obtained.

  In the optical system of FIG. 5, since the optical axis L3 of the lens 36 is substantially shifted and overlapped with the boundary between the 0th-order diffracted light and the 1st-order diffracted light, the expression (8) is expressed by the following expression (8) ′ It becomes.

Thus, the complex amplitude distribution E ₁ is the largest when y1 = a, and becomes 0 when y1 = 2a.
When y1 = 2a is viewed from the 0th-order diffracted light, information up to a spatial frequency corresponding to 3a is acquired. Therefore, it is possible to obtain up to 1.5 times the spatial frequency as compared with a lens having the same NA. Accordingly, the optical resolution is substantially improved.

  On the other hand, with respect to the −1st order diffracted light in the optical system symmetrical to the 1st order diffracted light with respect to the optical axis L0 of the 0th order diffracted light, similarly, if the direction perpendicular to the optical axis L2 of the −1st order diffracted light is the y ′ axis, The following equation (9) ′ is obtained.

Thus, the complex amplitude distribution E ₋₁ is the largest when y1 = −a, and is 0 when y1 = −2a.
When y1 = −2a is seen from the 0th-order diffracted light, information up to a spatial frequency corresponding to −3a is acquired. Therefore, it is possible to obtain up to 1.5 times the spatial frequency as compared with a lens having the same NA. Accordingly, the optical resolution is substantially improved as in the first-order diffracted light.
With respect to the information thus obtained, a difference output ΔI between the light output of the light receiving element 40 and the light receiving element 41 and the light receiving element equivalent to the −1st order diffracted light is obtained by the following equation.

  This is substantially the same as in the first embodiment. However, the optical system is simpler than that of the first embodiment, and is composed of simple elements such as a rhomboid prism. If the lens is molded integrally, a stable optical system can be obtained. Is possible. The same effect can be obtained even if the rhomboid prism is constituted by two half mirrors.

A third embodiment of the optical resolution improving apparatus according to the present invention will be described below with reference to FIG.
FIG. 6 is a schematic diagram showing the configuration of the optical resolution improving apparatus of the present embodiment. As shown in FIG. 6, also in this embodiment, the diffracted light transmitted through the sample S is emitted from the slide glass 72 (not shown in this embodiment), but with respect to the optical axis L0 of the 0th-order diffracted light. By inclining the lens 36, not only a part of the 0th-order diffracted light but also a part of the 1st-order diffracted light having a higher spatial frequency as compared with the case where the same lens is used, is formed. Interference is realized in the optical system. Although not shown, in the present embodiment, a similar optical system is disposed at a target position with respect to the axis L0.

  The process up to obtaining a part of the 0th-order diffracted light and a part of the 1st-order diffracted light by tilting the lens 36 is the same as in the second embodiment. In the present embodiment, the diffracted light beams converted into parallel light beams by the lens 36 are collected by the lens 52. The lens 52 causes the diffracted lights to overlap in the vicinity of the focal point and substantially interfere. However, since it is not interference between the 0th order diffracted light and the ± 1st order diffracted light, it is different from the image formation of the sample S itself.

  Furthermore, by increasing the effective focal length of the lens 52, the pitch of interference fringes can be increased. If the focal lengths of the lens 36 and the lens 52 are the same, it will naturally be the same magnification and become the spatial frequency of the sample S. On the other hand, the result of interference by the optical system of the other −1st order diffracted light is an interference fringe having a shifted pitch. However, if the light receiving element is larger than the pitch of the interference fringes, it is difficult to align the element that receives ± first-order diffracted light.

  Therefore, if the interference fringes themselves are magnified by the magnifying optical system 53 and made substantially equal to the size of the light receiving element 50, the ± first-order diffracted light has an opposite phase naturally, so that the zero-order diffracted light becomes a bias. The light and dark are reversed. In this way, information can be acquired very easily up to a region having a high spatial frequency. In this embodiment, since the lens 52 is used, a wavefront aberration that allows the phase difference between the 0th-order diffracted light and the 1st-order diffracted light incident on the lens 52 to be reflected as it is is allowed. Therefore, there is no need to use an expensive lens.

  In this embodiment, even if the lenses have slightly different focal lengths, the light amounts received by the light receiving elements are not significantly changed, and if the wavefront aberration in the lens surface is not large, the pitch of the interference fringes changes somewhat. It can be used as it is. Further, the limit of the spatial frequency that can be acquired is about 1.5 times because the principle is almost the same as in FIG. Since this optical system is constructed using only the lens system, it is very simple and resistant to disturbance.

Embodiment 4 of the optical resolution improving apparatus according to the present invention will be described below with reference to FIG.
FIG. 7 is a schematic diagram showing the configuration of the optical resolution improving apparatus of the present embodiment. Although this embodiment is employed in an optical system similar to that shown in FIG. 6, in this embodiment, instead of using the magnifying optical system 53 as shown in FIG. The structure is arranged near 52 focal points. In this embodiment as well, diffracted light that has passed through the sample S is emitted from a slide glass 72 (not shown), and although not shown, in this embodiment, an optical system similar to the target position with respect to the optical axis L0. Is arranged.

  As a result, the 0th-order diffracted light and the 1st-order diffracted light diffracted by the sample S are further diffracted by the grating 54, and the 0th-order diffracted light and the 1st-order diffracted light substantially interfere with each other. In FIG. 7, the shaded portion is the interference portion K where the 0th-order diffracted light and the 1st-order diffracted light overlap, but there is a similar interference portion K on the opposite side of the optical axis L3.

  Here, if the grating 54 is configured in a sine wave shape, the diffracted wave by the grating 54 is zero-order diffracted light and ± first-order diffracted light and has no phase difference. In this case, since the phase difference of the symmetric portion with respect to the optical axis L3 is the same, the overlapping portion is in phase. Therefore, in this embodiment, the light receiving element 50 may acquire the light amount of the portion including the interference portion K in at least two regions output from the grating 54.

  However, although the interference part K is symmetrical and in phase with the optical axis L0, the phase of the interference part K is inverted by 180 degrees in the −1st order diffracted light diffracted by the sample S. On the other hand, the intensities other than the interference part K are the same in the direction of the ± first-order diffracted light diffracted by the sample S. Information will remain.

  On the other hand, when the grating 54 is configured in a substantially sine wave shape that causes a phase difference, a phase difference of 180 ° is generated between the 0th-order diffracted light and the ± 1st-order diffracted light by the grating 54. In this case, as described above, the light amount including the interference portion K in at least one region output from the grating 54 by the light receiving element 50 may be acquired. However, the difference from the above reflects the phase difference of the grating 54, and therefore also reflects the position of the grating 54 relative to the beam. Therefore, it is necessary to adjust the position of the grating 54 with respect to the beam.

  It should be noted that the position adjustment is very simple and is adjusted so that the intensity modulation of the light receiving elements 50 on both sides observed by scanning is maximized with respect to the sample S of the phase grating having a certain spatial frequency prepared in advance. And what is necessary is just to make it a phase difference become 180 degrees on both sides. As described above, the differential output of the intensity of the ± first-order diffracted light leaves only the information on the interference part K.

Embodiment 5 of the optical resolution improving apparatus according to the present invention will be described below with reference to FIG.
FIG. 8 is a schematic diagram showing the configuration of the optical resolution improving apparatus of the present embodiment.
In this embodiment, a grating 54 similar to that shown in FIG. 7 is used in another optical system. In this embodiment, diffracted light transmitted through the sample S is emitted from a slide glass 72 (not shown). As shown in FIG. 8, in addition to the lenses 15, 16, and 17, the structure is similar to that of the first embodiment having the reflecting mirrors 18 and 19. However, in place of the absence of the beam splitters 12A, 12B, 13, 14 and the like, the lens 55 is disposed below the reflecting mirror 18, and a grating is provided between the lens 55 and the light receiving element 57 and at the focal position of the lens 55. 54 is arranged.

  Furthermore, the lens 15 is made large, and part of the light beam that has passed through the lens 15 is incident on the lens 55, so that the lens 15 operates in the same manner as in the fourth embodiment. Further, the lens 56 is disposed below the reflecting mirror 19, and the grating 54 is disposed between the lens 56 and the light receiving element 58 and at the focal position of the lens 56 as described above. For this reason, the lens 56, the grating 54, the light receiving element 58 and the like also operate in the same manner as described above.

An optical resolution improving apparatus and a slide glass according to a sixth embodiment of the present invention will be described below with reference to FIG. 9 using an example in which the sixth embodiment of the DPC method shown in FIG. 3 is applied.
As shown in FIG. 9, the process is the same as that in FIG. 2 until the parallel light beam enters the objective lens 31 and is converged on the sample S. However, in this embodiment, instead of the slide glass 72, the surface of the convex portion 74B has a lens surface shape and has a curvature in which the focal position F of the surface of the convex portion 74B is located. A slide glass 74 is employed.

  As a result, the 0th-order diffracted light and the ± 1st-order diffracted light diffracted by the sample S and incident on the slide glass 74 are squeezed from the slide glass 74 toward the light receiving element 29, and are emitted slightly. Interference of first-order diffracted light is realized. For this reason, even if it is 1st-order diffracted light with a larger diffraction angle, information with higher spatial frequency can be acquired as it becomes possible to acquire diffracted light with a light receiving element of the same size. . Further, if the curvature of the surface of the convex portion 74B is set to a curvature having a focal point in the vicinity of the sample S, the light emitted from the slide glass 74 travels almost straight as it is, and the Fourier of the sample S on the light receiving element 29. Conversion will be obtained.

An optical resolution improving apparatus and a slide glass according to Example 7 of the present invention will be described below with reference to FIG. 10 using an example in which the optical system of the DPC method shown in FIG. 3 is applied.
This embodiment is the same as FIG. 3 until the parallel light beam enters the objective lens 31 and converges on the sample S as shown in FIG. However, in this embodiment, instead of the slide glass 72, a slide glass 76 in which the refractive index of the member constituting the convex portion 76B is higher than the refractive index of the member constituting the main body portion 76A which is the other portion is adopted. Has been.

By using the slide glass 76, when the 0th-order diffracted light and the ± 1st-order diffracted light transmitted through the sample S are incident on the convex portion 76B from the main body portion 76A, the diffracted light tends to converge. In FIG. 10, both ends in the figure of the 0th-order diffracted light that is the optical axis L0 are optical edge portions L0a and L0b, and both ends in the diagram of the 1st-order diffracted light that is the optical axis L1 are optical edge portions L1a and L1b. And both end portions in the figure of the −1st order diffracted light that is taken as the optical axis L2 are represented as optical edge portions L2a and L2b.
For this reason, when the light receiving element 29 is emitted from the slide glass 76 and receives the diffracted light, information having a higher spatial frequency can be acquired as in the sixth embodiment.

  An optical resolution improving apparatus and a slide glass according to an eighth embodiment of the present invention will be described with reference to FIGS. 11 and 12, using an example in which the optical system of the DPC method shown in FIG. In this embodiment, as shown in FIG. 11, the slide glass 78 is provided with a plurality of convex portions 78B, and the sample S can be placed at a position on the laser light source 21 side of the slide glass 78 facing the convex portions 78B. Recesses 78E are respectively provided.

  Therefore, according to the present embodiment, by having a plurality of the recesses 78E, it is possible to cultivate a single cell or a plurality of cells or the like in these, and to provide a certain range of motion for the plankton or cells that move. Since it can restrict | limit, it becomes easy to observe the sample S. FIG.

  Since the sample S can be set in each of the plurality of recesses 78E, a number is assigned to each recess 78E, and a table (not shown) that supports the slide glass 78 is used as an electric stage, and the reading position of the electric stage is set. It is also conceivable to store this number together. In this way, it is possible not only to easily manage individual cultured cells, but also to enable efficient observation as each sample S can be observed sequentially. As a result, cells and the like can be cultured in each of the recesses 78E, and it is possible to easily observe the change of many cells over time as three-dimensional information having phase information.

  Furthermore, the convex part of the slide glass is constituted by a plano-convex lens having a certain curvature, and the flat part of a commercially available plano-convex lens having an appropriate focal length is bonded to the main body part or integrally formed, A slide glass may be created. By using the plano-convex lens in this way, the diffracted light becomes convergent light as the focal position can be set in the cover glass. In this case, the area of the light receiving element that acquires spatial frequency information can be reduced at the same time that a high spatial frequency can be extracted.

The material of the slide glass described in each of the embodiments according to the present invention described above is not limited to the glass material as the name suggests, and may be a transparent and robust material, such as a plastic material. Conceivable. Furthermore, the main body portion and the convex portion of the slide glass may be integrally formed, or as described above, the convex portion such as a plano-convex lens may be integrated on the lower surface of the main body portion. In addition to the cells, the sample may be a transparent material, and the aqueous solution may be oil or water.
The embodiments according to the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  Since the optical resolution improving apparatus and the slide glass of the present invention can receive diffracted light transmitted through the measurement object more reliably, it can be applied not only to a microscope but also to measuring instruments such as various types of optical instruments, The resolution of these optical devices can be improved.

4, 5 2nd light receiving element group 6 1st light receiving element 10 Laser light source 11 Objective lens 12A, 12B 1st beam splitter 13, 14 2nd beam splitter 15, 16, 17 Lens 18, 19 Reflecting mirror 21 Laser Light source 22 Collimator lens 23 Acousto-optic element 24 AOD driver 25 Pupil transmission magnification lens system 26 Two-dimensional scanning device 27 Beam splitter 28, 29 Light receiving element 30 Pupil transmission lens system 31 Objective lens 33 Comparator 34 Data processing section 36 Lens 39 Ron Void prism 40, 41, 42 Light receiving element 50 Light receiving element 52 Lens 53 Magnifying optical system 54 Grating 55, 56 Lens 57, 58 Light receiving element 64, 65 Lens 71 Cover glass 72, 74, 76, 78, 172 Slide glass E Aqueous solution Focus P center of curvature S samples L0, L1, L2, L3, LX optical axis

Claims (8)

A light source for irradiating a measurement object with a light beam;
A light receiving element that receives light transmitted through the measurement object;
A slide disposed between the light receiving element and the light source, the measurement object can be placed on the light source side surface, and a convex portion having a curved surface is provided on the light receiving element side surface Glass,
An optical resolution improving apparatus. The light receiving element is composed of a first light receiving element and a pair of second light receiving elements, and the slide glass is an optical resolution improving device arranged between the light receiving element and the light source,
A first lens that is located on the irradiation optical axis of the luminous flux and converts the luminous flux that has passed through the measurement object and the slide glass into a parallel luminous flux;
A first light-receiving element having at least two divided light-receiving elements that respectively receive light on each side portion across the irradiation optical axis of transmitted light that has passed through the first lens;
A light beam that is located on an inclined optical axis that has an inclination on each side on which the divided light receiving elements of the first light receiving element receive light with respect to the irradiation optical axis and that has passed through the measurement object and the slide glass. A pair of second lenses each having a parallel luminous flux;
An optical element that causes interference between the light beam emitted from the first lens and the light beam emitted from each of the second lenses;
A pair of second light receiving elements for receiving each light beam interfered by the optical element;
An output sum difference detection unit for detecting an output sum or output difference between the divided light receiving elements located across the irradiation optical axis of the first light receiving element and an output sum or output difference between the pair of second light receiving elements; ,
The optical resolution improving apparatus according to claim 1, comprising: The light receiving element is composed of a plurality of light receiving elements and a plurality of second light receiving elements, and the slide glass is an optical resolution improving device arranged between the light receiving elements and the light source,
A lens that is positioned on an inclined optical axis that is inclined with respect to the irradiation optical axis of the convergent irradiation, and that makes the light beam transmitted through the measurement object and the slide glass a parallel light beam;
A first light beam that passes through a portion of the lens near the irradiation optical axis of a light beam incident on the lens and a second light beam that passes through one half of the lens far from the irradiation optical axis interfere with each other. An optical element of
A plurality of first light receiving elements for respectively detecting light beams interfered by the first optical element;
A second optical element disposed in a direction opposite to the first optical element with respect to the inclined optical axis, and causing the first light beam and the second light beam to interfere with each other;
A plurality of second light receiving elements for respectively detecting light beams interfered by the second optical element;
An output sum / difference detector for detecting an output value of a sum or a difference between an arbitrary received light output of the plurality of first light receiving elements and an arbitrary received light output of the plurality of second light receiving elements;
The optical resolution improving apparatus according to claim 1, comprising:   The optical resolution improving apparatus according to any one of claims 1 to 3, wherein a surface of the convex portion is spherical, and a center of curvature of the convex portion is located on a surface of the slide glass on the light source side.   The optical resolution improving apparatus according to any one of claims 1 to 3, wherein the surface of the convex portion has a lens surface shape, and a focal position of the surface of the convex portion is located in the slide glass.   The optical resolution improving apparatus according to any one of claims 1 to 5, wherein a refractive index of a member constituting the convex portion is higher than a refractive index of a member constituting another part of the slide glass.   The optical device according to any one of claims 1 to 6, wherein a plurality of the convex portions are provided, and concave portions in which a measurement object can be placed are provided at positions on the light source side of the slide glass facing the convex portions, respectively. Resolution improvement device. It is a plate-shaped slide glass that is used in an optical instrument that allows an object to be measured to be installed and observes the object to be measured,
A slide glass provided with a convex portion having a curved surface formed integrally with another portion or bonded to the other portion.

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