JP2002162569A - Illumination optical system and optical device having the illumination optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical system which is constituted compact in size, more particularly, the illumination optical system which can be lowered in the height of a stage, and to provide an optical device using this illumination optical system. SOLUTION: A diffraction optical element is arranged between a light source and an object. This diffraction optical element is provided with patterns for deflecting the luminous flux from the light source to the object side. If the direction normal to the surface of the stage for holding the object is defined as Z-axis, and the angle formed by a normal to the surface of the diffraction optical element and the Z-axis is defined as α, the diffraction optical element is so arranged as to satisfy the equation 0 deg.<α<45 deg.. The illumination optical system, having the diffraction optical element described above, is used for the optical device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system having a diffractive optical element utilizing diffraction, such as a hologram optical element, and an optical apparatus having the illumination optical system.

[0002]

2. Description of the Related Art In medical examinations such as cytodiagnosis, an extremely large number of specimens are handled, and observation time is long. In such a cell diagnosis, the exchange of specimens is often performed manually by an observer one by one. In some cases, automation is performed by a machine, but it is only a small part. Reasons include the fact that the equipment becomes large when automated, a large work space is required, and glass products such as slide glass and liquid specimens in culture medium are difficult to handle with a machine. .

FIG. 11 shows a conventional microscope used for examination such as cytodiagnosis, wherein 1 is a specimen, 2 is a stage for holding the specimen, 3 is a condenser, 4 is a mirror, and 6 is a mirror.
Is a transmission light pipe, 7 is an objective lens, 10 is an illumination light beam, 60
Denotes an optical axis of the objective lens 7, and 70 denotes a work table. In this microscope, the stage 2 moves up and down along the optical axis 60.
Therefore, the observer moves the stage 2 to move the specimen 1
You will focus on Further, when exchanging the specimen, it is necessary to largely move the stage 2 to the workbench 70 side. Since the condenser 3 also moves with the movement of the stage 2, the luminous flux 10
Are parallel or substantially parallel.

FIG. 12 shows another conventional microscope. Instead of fixing the stage 2, an objective lens 7 is used.
This is a microscope of a type that adjusts the focus of the sample 1 by moving the microscope up and down. In this microscope, since the stage 2 does not move up and down, a space for moving the stage 2 below the stage 2 is not required. Further, since the condenser 3 is also fixed, the light flux 10 incident on the condenser 3 does not need to be a parallel or substantially parallel light flux.

FIG. 13 shows an example of a conventional transmission type dark field illumination optical system. In this dark field illumination optical system, FIG.
Stage 2 instead of the condenser lens 3 of FIG.
A mirror 8 for dark-field illumination is arranged between the mirror 4 and the mirror 4. The dark field illumination mirror includes a first mirror 8a and a second mirror 8b. The first mirror 8a is arranged so as to split the light beam reflected by the mirror 4 into two light beams around the optical axis 60. First mirror 8
The light beam reflected by a travels in a direction away from the mirror optical axis, and enters the second mirror 8b. The mirror 8b is arranged such that its reflection surface reflects in a direction facing the first mirror 8a and at an angle that does not enter the objective lens 7. Therefore, the light beam 45 reflected by the mirror 8b is
As shown in FIG. 3, the light flux illuminates the sample obliquely at an angle that does not enter the objective lens 7.

All of the above examples relate to an illumination optical system.
There is 134303 publication. Japanese Patent Laying-Open No. 4-134303 relates to an imaging optical system using an off-axis hologram optical element. FIG.
FIG. 1 is one of the diagrams disclosed in Japanese Patent Publication No. 303, and shows an imaging optical system in a rigid distal end portion of a side-view type endoscope.
14, 31 is a concave lens, 32 is a convex lens group,
33 is an objective lens, 34 is an image guide fiber, 3
5 is an off-axis hologram optical element, and 36 is a prism. The objective lens 33 is composed of a concave lens 31 and a convex lens group 32, and forms an image of a specimen (not shown) on the incident end face of the image guide fiber 34.

The prism 36 has a reflecting surface for deflecting the incident light at right angles in order to guide the light from the sample to the image guide fiber 34, and the off-axis hologram optical element 35 is provided on this reflecting surface. . The hologram element is an optical element utilizing the diffraction effect of light, and has a characteristic that the light deflection direction can be freely set. Therefore, even if the apex angle の of the prism 36 is smaller than 45 degrees, the light can be deflected by 90 degrees. As a result,
The length L along the longitudinal direction of the imaging optical system can be reduced as compared with the related art.

[0008]

In the conventional microscope shown in FIG. 11, when the conventional microscope is installed on the worktable 70, the height of the stage 2 holding the specimen 1 is considerably higher than the worktable 70. It is in. The microscope shown in FIG. 11 employs a method in which the stage 2 is moved up and down to focus on the specimen. In this case, basically, a space enough to move the stage 2 for focusing may be secured around the stage 2. However, in consideration of the operability, it is necessary to keep a wide space between the objective lens 7 and the sample 1 in order to easily exchange the sample 1. Therefore, a space larger than the space required for focusing is required below the stage 2.

On the other hand, considering the optical performance, it is necessary to dispose a condenser 3 for illuminating the specimen 1 with an appropriate illumination field and NA under the microscope stage 2. At this time,
In order to properly illuminate the specimen 1 even when the stage 2 moves up and down along the optical axis 60, the condenser 3 must move up and down together with the stage 2. Moreover, the light beam 10 from the light source (not shown) needs to be incident on the condenser 3 as a parallel light beam. For this reason, the configuration of the illumination optical system is complicated, and it is difficult to reduce the size of the condenser 3. Due to various factors as described above, the position of the stage 2 with respect to the worktable 70 is high in the conventional microscope of FIG.

By the way, in the cell diagnosis, the observer lowers the stage 2 every time the sample 1 is replaced, and then lowers the sample 1 from the stage 2 to the work table 70 once.
Further, another specimen on the work table 70 must be lifted to the stage 2 and the stage 2 must be moved again to a position near the focus position. Such an operation is a larger operation for the observer than an operation of operating the stage in order to search for an observation position or focus. Therefore, if a large number of specimens are exchanged, the observer may experience an increase in physical fatigue, for example, dropping the specimen.

On the other hand, as shown in FIG.
Although a microscope in which the height of the stage 2 is lowered by fixing the stage has been devised, the height of the stage is not yet sufficiently low. Further, in order to bring the position of the stage 2 closer to the worktable 70, the illumination optical system below the stage 2 must be made more compact. However, usually, in order to obtain a 90-degree deflection angle with a mirror or a prism, the angle between the normal to the reflection surface and the illumination optical axis must always be 45 degrees. Further, since a large NA is required to perform sufficiently bright illumination, the light beam 10 incident on the condenser 3 cannot be made thin. Therefore, FIG.
The height of the stage 2 shown in FIG. 2 is adjusted by a condenser 3 provided below the stage 2 and a mirror 4 arranged at 45 degrees to deflect the light beam from the light source 90 degrees toward the objective lens 7.
In addition, it is limited by the size of the illumination light beam 10 and cannot be reduced any more.

In the dark field illumination optical system shown in FIG. 13, it is necessary to deflect the illumination light beam 45 so that it does not directly enter the objective lens 7. Therefore, the illumination light beam 10 must be reflected a plurality of times using the complicated dark-field illumination mirror 8 and guided to the sample 1, and the space under the stage cannot be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an illumination optical system having a compact configuration, and in particular, an illumination optical system capable of reducing the height of a stage. I do. It is another object of the present invention to provide an optical device using the illumination optical system.

[0014]

To achieve the above object, an illumination optical system according to the present invention is an illumination optical system including a diffractive optical element disposed between a light source and an object, wherein the diffractive optical element is provided. Has a pattern for deflecting a light beam from the light source to the object side.

Another illumination optical system is the illumination optical system described above, wherein the normal direction of the surface of the stage holding the object is the Z axis, and the normal of the surface of the diffractive optical element and the Z axis are different from each other. When the angle is α, the diffractive optical elements are arranged so as to satisfy the following equation.

0 ° <α <45 ° Further, an optical device using the illumination optical system of the present invention has an illumination optical system disposed between a light source and an object, and an illumination optical system opposite to the illumination optical system with the object interposed therebetween. An optical system comprising an objective lens arranged on the side and an imaging optical system for imaging a light beam from the objective lens, wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element includes the diffractive optical element. It has a pattern for deflecting a light beam from a light source to the object side.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An illumination optical system according to the present invention is an illumination optical system having a diffractive optical element disposed between a light source and an object, wherein the diffractive optical element transmits a light beam from the light source to the object side. The pattern has a pattern that deflects the light. According to this illumination optical system, a diffractive optical element is used instead of a mirror that deflects a light beam from a light source toward an objective lens. There is no need to arrange them each time. Therefore, the degree of freedom in the arrangement of the illumination optical system increases, and the illumination optical system can be made compact. As a result, when this illumination optical system is used for a microscope, the height of the stage can be reduced.

In the illumination optical system, when the normal direction of the surface of the stage holding the object is the Z axis and the angle between the normal of the surface of the diffractive optical element and the Z axis is α,
It is preferable that the diffractive optical element is arranged so as to satisfy the following expression.

0 ° <α <45 ° According to this illumination optical system, the diffractive optical element for deflecting the light beam from the light source to the object side is arranged closer to the horizontal than 45 degrees, so that the optical system The space occupied can be reduced in the height direction. As a result, when this illumination optical system is used for a microscope, the height of the stage can be reduced.

In the illumination optical system, the diffractive optical element may be arranged so as to convert an incident light beam from the light source into a light beam diameter larger than the incident light beam and emit the converted light beam, or a circular beam from the light source. Arranged to emit the light beam as an elliptical light beam larger than the circular light beam, or
It is preferable to dispose the elliptical light beam from the light source so as to emit the elliptical light beam as a light beam whose diameter in the minor axis direction is enlarged. According to this illumination optical system, the light beam from the light source to the diffractive optical element can be narrowed, and the space occupied by the illumination light beam can be reduced. Also, the illumination optical system can be configured so that the light flux from the light source is converted to a large thickness by the diffractive optical element and the NA required for illumination is satisfied.

In the illumination optical system, a second diffractive optical element separate from the diffractive optical element is provided, and the diffractive optical element and the second diffractive optical element as a whole cancel out dispersion due to a diffraction effect. It is preferable to arrange them in such a manner. Alternatively, when an even number of the diffractive optical elements are provided, and the diffractive optical elements are paired with two identical elements, and one of the diffractive optical elements forming the pair has an incident angle of φ1 and an exit angle of φ2, the pair The other diffractive optical element forming
It is preferable that the diffractive optical elements forming the pair are arranged in parallel with each other so that the exit angle becomes φ1. According to this illumination optical system, dispersion due to the diffraction effect can be canceled out, so that flare and color unevenness of illumination light can be suppressed.

In the illumination optical system, it is preferable that the diffractive optical element is a transmissive diffractive optical element or a reflective diffractive optical element. Further, the optical device of the present invention,
An illumination optical system disposed between the light source and the object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an imaging optical system for imaging a light beam from the objective lens. Preferably, the illumination optical system includes a diffractive optical element, and the diffractive optical element has a pattern for deflecting a light beam from the light source toward the object. Accordingly, if the optical device is, for example, a microscope, the stage position can be arranged lower than the conventional one. Therefore, the burden on the observer can be reduced even when the observer has few movements and observes for a long time or handles a large number of samples.

Further, another optical apparatus according to the present invention comprises: an illumination optical system disposed between a light source and an object; and a condensing objective lens disposed on the same side of the object as the illumination optical system. And an imaging optical system for imaging a light beam from the objective lens, wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element transmits a light beam from the light source to the object side. It is preferable to have a pattern that deflects the light to the right. As a result, if the optical device is, for example, a microscope, the distance between the objective lens and the imaging optical system can be made shorter than that of the conventional device, and the vignetting due to the frame of the imaging optical system is reduced, and the peripheral light amount of the observed image Shortage can be reduced. Also, if the peripheral light amount is the same, more intermediate lens barrels can be mounted, and the system is excellent in systemicity.

Further, another optical apparatus according to the present invention comprises an illumination optical system disposed between a light source and an object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an objective lens. An optical system for imaging a light beam from the light source, wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element biases the light beam from the light source with respect to the object. It is preferable to have a pattern to illuminate. Accordingly, if the optical device is, for example, a microscope, even if the stage position is kept low, oblique illumination is possible, and a three-dimensional image can be observed.

Further, another optical device according to the present invention comprises an illumination optical system disposed between a light source and an object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an objective lens. And an imaging optical system that forms an image of a light beam from the object, wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element is at an angle that does not directly enter the objective lens with respect to the object. It is preferable to have a pattern for deflecting light. Thus, if the optical device is, for example, a microscope, dark field illumination can be performed without using a complicated mirror group, and the stage position of the microscope can be lowered.

In the above optical device, a second diffractive optical element is provided separately from the diffractive optical element, and the diffractive optical element and the second diffractive optical element have respective diffraction surfaces parallel to each other. It may be arranged in such a manner.

In the above optical device, a second diffractive optical element is provided separately from the diffractive optical element, and each of the diffractive optical elements and the second diffractive optical element has a mirror image relation. It may be arranged in such a manner.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A feature of the present invention is that a holographic optical element (HOL) is used instead of a mirror arranged in an optical path for guiding light from a light source to a sample.
E) is used. Here, the hologram element will be described. The hologram element is one of the diffractive optical elements utilizing the diffraction effect of light, and has a periodic structure which is a pattern for diffracting light, for example, a grating pattern. Examples of the pattern include a pattern in which a grating is formed on the surface of the device by irregularities, and a pattern in which a silver salt film or a polymer material is exposed to light to change the refractive index to form a grating inside the device.

FIG. 10 shows a phenomenon that light incident on the hologram element is diffracted by a pattern. The light 41 incident on the hologram element is diffracted by a grating 43 formed on the hologram element to become an emission light 42. At this time, an exit angle θ ′ diffracted by the grating 43 and emitted is an incident angle θ, a wavelength λ, and a grating interval d.
The relationship is represented by the following equation (1).

D (n · sin θ−n ′ · sin θ ′) = mλ (1) n and n ′ represent the refractive index of the medium at the wavelength λ, and m is an integer and represents the order of the diffracted light. FIG. 10 shows the diffraction by the transmission type hologram element as an example. In the case of the reflection type, the relation of the expression (1) is satisfied by considering that n = n ′ and θ ′> 90 °.

In the hologram element, the angle θ 'of the diffracted light to be emitted can be changed by changing the interval d of the grating. Therefore, unlike a normal reflection mirror in which the angle at which light is deflected depends only on the inclination of the element, the polarization direction of the light can be set freely independently of the inclination of the element. Hereinafter, an illumination optical system and an optical device of the present invention using a hologram element will be described using examples.

(First Embodiment) A first embodiment of the illumination optical system according to the present invention.
An embodiment is shown in FIG. Here, the illumination optical system of this embodiment is a transmission illumination optical system that irradiates illumination light from below the sample. The same components as those in FIG. 11 are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, one hologram element is provided as a diffractive optical element.
Are used in place of the mirror 4 shown in FIG. The light emitted from the light source 12 is collected by a lens (not shown) and emitted as a parallel or substantially parallel light flux 5. In this embodiment, since the hologram element 9 is disposed below the condenser 3, the light beam 5 from the light source 12 is diffracted by the hologram element 9, which is a diffractive optical element, and is deflected toward the sample 1. Here, the pattern provided on the hologram element 9 is a pattern that deflects the light beam 5 by 90 ° into the light beam 10 when the hologram element 9 is arranged at a predetermined angle. When the deflected light beam 10 illuminates the sample 1 on the stage 2 via the condenser 3, the objective lens 7
The pattern satisfies the required NA and Teruno.

Comparing FIG. 1 of the present embodiment with FIG. 11 of the conventional example, it can be seen that the hologram element 9 of the present embodiment is arranged at an angle closer to the horizontal than the mirror 4 of the conventional example. . Here, the normal direction of the surface on which the stage 2 holds the specimen 1 (this surface is a horizontal surface) is defined as the Z axis,
Assuming that the angle between the normal to the surface of the hologram element 9 and the Z axis is α, the hologram elements are arranged so as to satisfy the following equation.

0 ° <α <45 ° (2) As described above, the hologram element 9 is an element that changes (deflects) the traveling direction of light using diffraction, and the deflection direction can be set freely. it can. Therefore, even when the light beam 5 from the light source 12 is deflected by 90 ° toward the sample 1, the light beam 5 can be arranged at an angle closer to the horizontal than the mirror. That is, the ratio of the hologram element 9 spatially occupied in the height direction is smaller than that in the case where the light is deflected by the mirror 4 shown in FIG. Can be configured. If the light emitting tube 6 is used for a microscope, for example, the position of the stage 2 can be lowered. As a result, the sample 1 can be easily replaced, and the fatigue of the observer can be reduced.

(Embodiment 2) FIG. 2 shows a second embodiment of the present invention. This embodiment is also a transmission-type illumination optical system, and includes a first hologram element 9 and a second hologram element 11. Here, since the first hologram element 9 is arranged in the same manner as in the first embodiment, detailed description will be omitted, and the second hologram element will be described.

In this embodiment, the first hologram element 9 and the second hologram element 11 are arranged such that their diffraction surfaces face each other. The light emitted from the light source 12 is
The light is condensed by the collector lens 13 and emitted as a parallel or substantially parallel light flux 14. The light beam 14 emitted from the collector lens 13 is diffracted by the second hologram element 11. Here, although the angle between the normal to the surface of the second hologram element 11 and the optical axis of the light beam 14 is smaller than 45 degrees, the light beam is diffracted by a predetermined pattern provided on the second hologram element 11 and 14 is deflected 90 °.
Therefore, the space occupied by the second hologram element 11 can be reduced in the height direction as compared with the case where the light is deflected by the mirror.

Although the cross section of the light beam 14 incident on the second hologram element 11 from the light source 12 is circular, the light beam 5 deflected by the second hologram element 11
It has been converted to an elliptical shape with a short axis in the height direction. Therefore, the space in the light emitting tube 6 through which the light beam passes can be reduced in the height direction.

The light beam 5 diffracted and emitted by the second hologram element 11 is deflected toward the sample 1 by the first hologram element 9. In the first hologram element 9, the angle formed by the normal of the surface of the hologram element and the incident light beam 5 is larger than 45 °, which is opposite to that of the second hologram element 11, Angle α is the condition (2)
Means that you are satisfied. Therefore, the light beam 5 converted into the elliptical light beam by the second hologram element 11 is expanded in the short axis direction by the first hologram element 9, and has a light beam diameter sufficient to illuminate the sample 1 through the condenser 3. Further, the space occupied by the first hologram element 9 can be reduced in the height direction as compared with the case where the light is deflected by a mirror. As described above, by using the hologram element for the illumination optical system, the space occupied by the optical system and the light beam in the light projecting tube 6 can be reduced. Therefore, when such a light emitting tube 6 is used for a microscope, the position of the stage 2 can be configured low.

When the first hologram element 9 and the second hologram element 11 are constituted by the same element, and the incident angle of the second hologram element 11 is φ1 and the exit angle is φ2,
The incidence angle of the second hologram element 9 is φ2 and the emission angle is φ1
It is configured so that In this way, by configuring the respective diffraction surfaces to be mirror images, it is possible to return the light beam emitted by the first hologram element 9 to a circular light beam before being incident on the first hologram element 11. it can. As a result, illumination satisfying the NA and the illumination field required by the objective lens 7 can be performed without waste.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
Shown in This embodiment is also a transmissive illumination optical system like the second embodiment, and includes the first hologram element 9 and the second hologram element 11, but the arrangement is slightly different from that of the second embodiment. Is different.

The light emitted from the light source 12 is collected by the collector lens 13 and emitted as a parallel light flux 14. The light beam 14 emitted from the collector lens 13 is diffracted by a predetermined pattern provided on the second hologram element 11. Here, the second hologram element 11
The pattern provided at the angle at which the light flux is reflected when the mirrors are arranged in the same manner (hereinafter, referred to as a specular reflection angle)
The pattern is such that it is diffracted at an angle larger than that. Therefore, the second hologram element 11 can be arranged at an angle closer to the horizontal than the mirror, and in this state, the light beam can be deflected in a desired direction.

The light beam diffracted and emitted by the second hologram element 11 is reflected by the mirror 15. The mirror 15 is arranged so that its reflection surface is substantially parallel to the second hologram element 11, and converts the incident light beam into the first hologram element 11.
Is reflected toward the hologram element 9. The light beam 5 reflected by the mirror 15 enters the second hologram element 9, where it is diffracted and deflected to the sample 1 side.

In the second embodiment, the first hologram 9
The light beam 5 incident on the first hologram element 9 in this embodiment is an inclined light beam, whereas the light beam 5 incident on the stage 2 or the surface of the worktable is horizontal. This is because, in this embodiment, the second hologram element 11
This is because the light beam is once deflected upward (toward the stage 2) and then reflected downward (toward the workbench 70) by the mirror 15. In such a configuration, the angle between the normal to the surface of the first hologram element 9 and the optical axis 60 of the objective lens is larger than the angle between the normal to the surface of the first hologram element 9 and the light beam 5. small. For this reason, the space occupied by the optical system can be reduced in the height direction as in the first embodiment, as compared with the case of using a mirror.

In this embodiment, the same element is used for the second hologram element 11 and the first hologram element 9, and both hologram elements are arranged in parallel with each other. And
In this embodiment, the light beam is reflected using the mirror 15 in order to arrange the illumination optical system compactly in the light projecting tube 6. At this time, the mirror image of the second hologram element 11 by the mirror 15 is the first image. Are in parallel with the hologram element 9 of FIG. The hologram elements 9 and 11 are arranged in this manner for the following reasons. From equation (1), it can be seen that even when the lattice spacing d and the incident angle θ are constant, the exit angle θ ′ varies depending on the wavelength, and that the shorter the wavelength, the closer θ ′ to θ. This effect is called dispersion. Therefore, when white light is incident on the hologram element, the exit angle of the diffracted light varies depending on the wavelength, and as it is, there is a possibility that unevenness (color unevenness) will occur in illumination on the sample.

When the two hologram elements 9 and 11 are arranged so that their diffraction surfaces are parallel as shown in FIG. 3, the relationship between the incident light and the exit light with respect to the first hologram element 9 is as follows. This is equivalent to a state where the incident light and the emitted light are interchanged in the element 11. On the other hand, FIG.
It is clear that the equation (1) is satisfied even if the incident light 41 and the emitted light 42 are exchanged at 0. Therefore, in the case of the configuration as in the present embodiment, even if the light beam 5 is emitted from the second hologram element 11 at a different angle depending on the wavelength, the light beam having a different angle depending on the wavelength is diffracted by the second hologram element 9. At the same time. Therefore, in the configuration of the present embodiment, the illumination optical system without dispersion can be configured to be more compact than before.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment of the present invention.
Shown in This embodiment is an epi-illumination optical system that irradiates illumination light from above the sample. In this embodiment, the first hologram element 17 and the second hologram element 19 are arranged such that their diffraction surfaces are parallel to each other. Light emitted from the light source 12 is collected by the collector lens 13 and emitted as a parallel light flux 14. The light beam 14 emitted from the collector lens 13 is diffracted by the second hologram element 19. Although the angle between the normal to the surface of the second hologram element 19 and the optical axis of the light beam 14 is smaller than 45 degrees, the light beam 14 is diffracted by a predetermined pattern provided on the second hologram element 19. Is deflected by 90 °. Therefore, the space occupied by the second hologram element 19 can be reduced in the height direction as compared with the case where the light is deflected by a mirror.

Although the cross section of the light beam 14 incident on the second hologram element 19 from the light source 12 is circular, the light beam 5 deflected by the second hologram element 19 is
It has been converted to an elliptical shape with a short axis in the height direction. Therefore, the space in the light emitting tube 22 through which the light beam passes can be reduced in the height direction.

The light beam 5 diffracted and emitted by the second hologram element 19 is deflected toward the sample 1 by the first hologram element 17. First hologram element 17
Is opposite to the second hologram element 19, the angle between the normal to the surface of the hologram element and the incident light beam 5 is larger than 45 °. This means that (2) is satisfied. for that reason,
The light beam 5 converted into an elliptical light beam by the second hologram element 19 is expanded in the short axis direction by the first hologram element 17 and has a light beam diameter sufficient to illuminate the sample 1 through the objective lens 7. The illumination light reflected by the specimen 1 is condensed by the objective lens 7, transmitted through the first hologram element 17, formed into an image by the imaging optical system 20, and observed by an observation optical system (not shown).

In this embodiment, as compared with the configuration shown in FIG.
Of the hologram element 17 can be reduced in the height direction. As described above, by using the hologram element for the illumination optical system, the space occupied by the optical system and the light beam in the light projecting tube 22 can be reduced, and the light projecting tube 22 can be made smaller (thinner). Thereby, the objective lens 7
And the distance between the optical system and the imaging optical system 20 can be made shorter than before.

The effect obtained by reducing the distance between the objective lens 7 and the imaging optical system 20 will be described with reference to FIG. FIG. 6 shows the state of the off-axis light beam 29 and the on-axis light beam 30. As shown in FIG. 6, the ray height of the off-axis light flux 29 emitted from the objective lens 7 increases as the distance from the objective lens 7 increases. Therefore, the longer the distance between the objective lens 7 and the imaging optical system 20 becomes, the longer the imaging optical system 2 becomes.
The diameter of 0 must be increased. However, since the size of the imaging optical system 20 is limited, vignetting occurs in the off-axis light flux 29, which causes a decrease in the amount of light around the image to be observed. Therefore, the objective lens 7 and the imaging optical system 2
In the configuration of the present embodiment that can shorten the interval with 0, the light amount does not decrease around the image to be observed.
Moreover, the same hologram element 17 and the second hologram element 19 are used as the same hologram element 19 and the diffraction planes are arranged in parallel with each other, whereby the dispersion due to diffraction can be canceled.

(Fifth Embodiment) FIG. 7 shows a fifth embodiment of the present invention.
Shown in This embodiment is also an epi-illumination illumination optical system that emits illumination light from above the sample. In this embodiment, two light emitting tubes 2
2, 59 are provided. Light emitted from the light source 12 of the first light projecting tube 22 is collected by the collector lens 13 and emitted as a parallel light flux 14. The light beam 14 emitted from the collector lens 13 is the fourth hologram element 2
8. After being deflected by 90 ° by the third hologram element 27 and the second hologram element 26, the light is deflected by 90 ° toward the sample 1 by the first hologram element 17.

Here, since the angle between the normal to the surface of the fourth hologram element 28 and the optical axis of the light beam 14 is smaller than 45 degrees, they are arranged at an angle closer to the horizontal than in the case where a mirror is used. Will be. However, the light beam 14 is diffracted and deflected by 90 ° according to a predetermined pattern. Similarly, the first to third hologram elements 17, 26, and 27 are also arranged at an angle closer to the horizontal as compared with the case where a mirror is used, but since a predetermined pattern is provided, the incident light beam is deflected by 90 °. can do. As a result, the first light emitting tube 22 can be reduced in the height direction.

Further, in the present embodiment, the first hologram element 17 and the fourth hologram element 28 are arranged so that their diffraction surfaces are parallel to each other with the same element. Similarly, the third hologram element 27 is the same element and is arranged at a position such that the diffraction surfaces are parallel to each other. With such a configuration, the first light emitting tube 22
Is an optical system in which dispersion due to diffraction is offset as a whole.

As described above, since the thickness of the first light emitting tube 22 can be made thinner, another second light emitting tube 59 is provided on the first light emitting tube 22. be able to. In this case, the fifth hologram element 56 and the sixth hologram element 57 are also used for the second projection tube 59,
The arrangement is the same as in the fourth embodiment. Therefore, the light source 52
The light beam emitted from the hologram element is converted into a parallel light beam 55 by the collector lens 53, and is deflected by 90 ° by the sixth hologram element 57. The light beam 54 deflected by 90 ° by the sixth hologram element 57 enters the fifth hologram element 56 and is deflected by 90 ° toward the objective lens 7.

The fifth hologram element 56 and the sixth hologram element 57 arranged in the second light projecting tube 59 are also arranged at an angle closer to the horizontal than in the case where a mirror is used. Therefore, the thickness of the second light emitting tube 59 can be reduced as compared with the related art. Therefore, even if the first light projecting tube 22 and the second light projecting tube 59 are arranged between the objective lens 7 and the image forming optical system 20, the objective lens 7 and the imaging There is no large gap. Therefore, even in the configuration of the present embodiment, the light amount does not decrease around the image to be observed. Also, a very compact configuration can be realized while arranging two light emitting tubes.

(Sixth Embodiment) FIG. 8 shows a sixth embodiment of the present invention.
Shown in The illumination optical system of this embodiment is a transmission type oblique illumination optical system, and has almost the same configuration as that of the third embodiment shown in FIG. However, in the third embodiment, the capacitor 3 is used.
In that the hologram element 23 is used.

The light beam 10 deflected by the first hologram element 9 enters the third hologram element 23.
Here, the third hologram element 23 does not condense the entire light beam 10 toward the sample 1 like the condenser 3 but diffracts light so as to perform oblique illumination that irradiates the sample 1 from an oblique direction. I do. More specifically, a pattern is provided in the third hologram element 23 so that substantially parallel light beams in a ring shape cross at a predetermined angle on the sample 1 and are emitted as substantially parallel light beams. I have. In order to obtain a ring-shaped light beam, a light-blocking member that blocks the center of the light beam may be arranged in any of the light beams 14, 5, and 10, or a light-blocking region may be provided in the third hologram element 23. . In this case, if a light-blocking region is provided in the third hologram element 23, it is only necessary to separate the third hologram element 23 from the optical path when switching from oblique illumination to another illumination. preferable. Alternatively, it is also a preferable configuration to arrange a light shielding member in the vicinity of the third hologram element 23.

In this embodiment, the third hologram element 23
Thus, oblique illumination becomes possible, so that even if the sample is nearly transparent and is difficult to be distinguished by bright-field observation, the sample is shaded and an image with a three-dimensional effect can be obtained. Since the thickness of the third hologram element 23 is smaller than that of the capacitor 3,
The illumination optical system can be made more compact.

(Seventh Embodiment) FIG. 9 shows a seventh embodiment of the present invention.
Shown in The illumination optical system of this embodiment is a transmission type dark field illumination optical system. This embodiment also uses a hologram element 24 instead of the capacitor 3 as in the sixth embodiment. However, the hologram element 24 of the present embodiment is different from the hologram element 23 of the sixth embodiment in that the hologram element 24 has a pattern for diffracting a light beam at an even larger angle. In the sixth embodiment, the light beam diffracted by the hologram element 23 directly enters the objective lens 7, whereas in the present embodiment, the light beam diffracted by the third hologram element 24 does not directly enter the objective lens 7. Deflected to an angle. Therefore, the illumination optical system of the present embodiment is a dark-field illumination optical system that illuminates the specimen 1 in a dark-field.

In this embodiment, since the hologram element 24 is used as an optical element for performing dark-field illumination, a complicated dark-field illumination mirror 8 as shown in FIG. 13 is not required. Therefore, the illumination optical system can be made compact, and the position of the stage 2 can be lowered. Further, in the conventional example shown in FIG.
The size of the dark-field illumination mirror 8 must be as small as possible in order to keep the space up to this point small. As a result, the diameter of the light beam 10 shown in FIG.
As can be seen by comparing the diameters of 0, only a part of the light beam 10 emitted from the light source 12 can be used in the conventional dark-field illumination. On the other hand, when the hologram element 24 is used, the light beam 10 can be used almost completely. Therefore, brighter illumination can be performed as compared with the related art.

Although the hologram element in the first to seventh embodiments is a reflection type element, it may be constituted by using a transmission type element. Further, the hologram element can have a lens effect by continuously changing the grid interval d of the hologram element. Therefore, the condenser 3 and the collector lens 13 in the above embodiment can be constituted by a hologram element. Further, the lens effects of the condenser 3 and the collector lens 13 may be provided to, for example, the hologram elements 9 and 11 in FIG. Since the hologram element has substantially no thickness, the configuration described above can make the illumination system more compact.

In addition to the above, the present invention has the following features. 1. An illumination optical system including a diffraction optical element disposed between a light source and an object, wherein the diffraction optical element has a diffraction pattern for deflecting a light beam from the light source toward the object.

2. When the normal direction of the surface of the stage that holds the object is the Z axis, and the angle between the normal of the surface of the diffractive optical element and the Z axis is α, the diffractive optical element satisfies the following equation. It is characterized by being arranged so that
1． 2. The illumination optical system according to 1.

0 ° <α <45 ° The diffractive optical element is arranged so as to convert an incident light beam from the light source into a light beam diameter larger than the incident light beam and emit the light beam. 2. The illumination optical system according to 1.

4. The diffractive optical element is arranged so as to emit a circular light beam from the light source as an elliptical light beam larger than the circular light beam. 2. The illumination optical system according to 1.

5. The diffractive optical element is arranged so as to emit an elliptical light beam from the light source as a light beam whose diameter in the minor axis direction of the elliptical light beam is enlarged. 2. The illumination optical system according to 1.

6. A second diffractive optical element separate from the diffractive optical element, wherein the diffractive optical element and the second diffractive optical element are arranged so as to cancel dispersion due to a diffraction effect as a whole. Do 1. To 5.
The illumination optical system according to any one of the above.

7. The illumination optical system includes an even number of the diffractive optical elements, and the diffractive optical element includes a pair of two identical elements, and the incident angle of one diffractive optical element forming the pair is φ.
1. When the exit angle is φ2, the other diffractive optical element forming the pair is disposed so that the incident angle is φ2 and the exit angle is φ1, and the diffractive optical elements forming the pair are disposed parallel to each other. 1. To 5. The illumination optical system according to any one of the above.

8. The diffractive optical element is a transmission type diffractive optical element. From 8. The illumination optical system according to any one of the above. 9. The diffractive optical element is a reflection type diffractive optical element. From 8. The illumination optical system according to any one of the above.

10. An illumination optical system disposed between the light source and the object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an imaging optical system for imaging a light beam from the objective lens. An optical device comprising: an illumination optical system including a diffraction optical element, wherein the diffraction optical element has a diffraction pattern for deflecting a light beam from the light source toward the object.

11. An illumination optical system disposed between the light source and the object, an objective lens for condensing light which is disposed on the same side of the object as the illumination optical system, and an imaging optical system for imaging a light beam from the objective lens Wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element has a diffraction pattern for deflecting a light beam from the light source toward the object. .

12. An illumination optical system disposed between the light source and the object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an imaging optical system for imaging a light beam from the objective lens. An optical device, wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element has a diffraction pattern for obliquely illuminating a light beam from the light source on the object.

13. An illumination optical system disposed between the light source and the object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an imaging optical system for imaging a light beam from the objective lens. Wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element has a diffraction pattern that deflects light at an angle that does not directly enter the objective lens with respect to the object. apparatus.

14. A second diffractive optical element separate from the diffractive optical element, wherein the diffractive optical element and the second diffractive optical element are arranged such that respective diffraction surfaces are parallel to each other. Do 1. 2. The illumination optical system according to 1.

15. A second diffractive optical element separate from the diffractive optical element, wherein the diffractive optical element and the second diffractive optical element are arranged such that respective diffraction surfaces have a mirror image relationship. Do 1. 2. The illumination optical system according to 1.

[0076]

As described above, according to the present invention, by using a diffractive optical element for the illumination optical system, the illumination optical system can be made more compact than before. as a result,
The burden on the user can be reduced. In addition, by making the illumination optical system compact, it becomes possible to configure a plurality of optical systems in a smaller space than before, without impairing optical performance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a transmission-type illumination optical system according to a first embodiment of the present invention.

FIG. 2 is a view showing a transmission-type illumination optical system according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a transmission type illumination optical system according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating an epi-illumination type illumination optical system according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing an epi-illumination type illumination optical system using a conventional mirror.

FIG. 6 is a diagram illustrating a state of a light beam due to a difference in an interval between an objective lens and an imaging lens.

FIG. 7 is a diagram showing an epi-illumination type illumination optical system according to a fifth embodiment of the present invention.

FIG. 8 is a view showing a transmission type oblique illumination optical system according to a sixth embodiment of the present invention.

FIG. 9 is a view showing a transmission-type dark-field illumination optical system according to a seventh embodiment of the present invention.

FIG. 10 is a diagram illustrating the operation of the hologram element used in the present invention.

FIG. 11 is a diagram showing an illumination optical system used in a conventional microscope.

FIG. 12 is a diagram showing another illumination optical system used in a conventional microscope.

FIG. 13 is a diagram showing a dark-field illumination optical system used in a conventional microscope.

FIG. 14 is a diagram showing a distal end optical system used in a conventional endoscope.

[Explanation of symbols]

Reference Signs List 1 specimen 2 stage 3 condenser 4, 15, 21 mirror 5, 10, 14, 16, 45, 54, 55 luminous flux 6, 22, 59 floodlight tube 7, 33 objective lens 8, 8a, 8b dark-field illumination mirror 9 , 11, 17, 19, 23, 24, 26, 27, 2
8, 56, 57 Hologram element 12, 52 Light source 13, 53 Collector lens 20 Imaging lens 29 Off-axis light beam 30 On-axis light beam 31 Concave lens 32 Convex lens group 34 Image guide fiber 35 Off-axis hologram optical element 36 Prism 41 Incident light 42 Emission light 43 Lattice 60 Optical axis of objective lens 70 Workbench

Claims (3)

[Claims] 1. An illumination optical system including a diffractive optical element disposed between a light source and an object, wherein the diffractive optical element has a pattern for deflecting a light beam from the light source toward the object. Illumination optics. 2. The method according to claim 1, wherein a direction normal to a surface of the stage holding the object is defined as a Z-axis, and a normal to a surface of the diffractive optical element and the Z-axis.
2. The illumination optical system according to claim 1, wherein, when an angle between the axis and the axis is α, the diffractive optical elements are arranged so as to satisfy the following expression. 0 ° <α <45 ° 3. An illumination optical system disposed between a light source and an object, an objective lens disposed on the opposite side of the illumination optical system with respect to the object, and an image of a light beam from the objective lens. An optical device comprising an imaging optical system, wherein the illumination optical system includes a diffractive optical element, and the diffractive optical element has a pattern for deflecting a light beam from the light source toward the object. Optical device.