JPH11153754A - Illuminating optical system and axicon prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desired zonal luminous flux by a simple and inexpensive constitution. SOLUTION: This device is provided with one axicon prism 6 a converting a collimated laser beam into a diffused luminous flux having a conical wave front, a reflection member 8 reflecting the diffused luminous flux which has the conical wave front and is converted by the prism 6 and light beam separating means 2 and 4 separating the zonal luminous flux that is in parallel with an optical axis and is obtained by being reflected by the reflection member 8 and being transmitted through the prism 6 again from the collimated laser light beam.

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 using a laser beam, and more particularly to an annular illumination optical system, an optical drawing apparatus, and the like which are most suitable for use in a confocal laser scanning microscope (CLSM). The present invention relates to an illumination optical system and an axicon prism used in a repair device.

[0002]

2. Description of the Related Art Conventionally, a confocal laser scanning microscope has better resolution / contrast and resolution in the height direction of a sample as compared with an ordinary microscope. Widely used for observation and measurement.

In such a confocal type laser scanning microscope, an illumination optical system for increasing the depth of focus while increasing the resolution by forming the illumination light in a ring shape is disclosed in, for example, Japanese Patent Application Laid-Open No. H8 (1996). No. -15156.

FIG. 6 is a schematic diagram showing a configuration example of an illumination optical system for forming such annular light. In this illumination optical system, each axicon prism 6, 6 having the same refractive index and the same apex angle is used.
′ Are arranged facing each other with their optical axes aligned.

The light incident on the axicon prism 6 is refracted at an angle determined by the refractive index and the apex angle of the axicon prism 6 with respect to the optical axis, and has an annular shape perpendicular to the optical axis. The conical light having a sectional intensity is converted into a diffused light having a surface and emitted.

On the other hand, the light emitted from the axicon prism 6 'is also refracted at an angle determined by the refractive index and the apex angle of the axicon prism 6'. And the same apex angle, the light emitted from the axicon prism 6 'becomes an annular light flux parallel to the optical axis.

Therefore, when the annular light formed by such an illumination optical system is applied to, for example, a confocal laser scanning microscope, the resolution is improved and the depth of focus is increased as compared with a normal microscope. Increase. When such ring light is applied to an optical drawing apparatus or a repair apparatus,
In addition, a pattern having a high aspect ratio can be formed on the sample.

[0008]

However, in the above-described illumination optical system, two axicon prisms 6, 6 'are required to obtain a light flux having a ring shape and being parallel to the optical axis.
And the axicon prisms 6, 6 'need to have the same refractive index and the same apex angle.

In this case, two axicon prisms 6,
In order for 6 ′ to have the same refractive index, there is no problem if the same optical material is used. However, to have the same apex angle, high processing accuracy is required, and as a result, the manufacturing cost is increased.

Further, two axicon prisms 6, 6
Since it is necessary to arrange the 'coaxially, the assembly and adjustment are troublesome, and as a result, the cost is increased. Therefore, an object of the present invention is to provide an illumination optical system and an axicon prism that can obtain a desired annular light beam with a simple and inexpensive configuration.

[0011]

To achieve the above object, according to the illumination optical system of the first aspect of the present invention, a collimated laser beam is converted into a diffused beam having a conical wavefront. Axicon prisms, a conical shape converted by the axicon prism, a reflecting member that reflects a diffused light beam having a surface, and an annular shape obtained by being reflected by the reflecting member and passing through the axicon prism again. And a light beam separating means for separating the light beam parallel to the optical axis from the collimated laser light.

Therefore, with such an illumination optical system,
The collimated laser beam is incident on the axicon prism, and the light beam incident on the axicon prism is a diffused light beam having a conical wavefront, reflected by the reflecting member, and again incident on the axicon rhythm.

In this case, the luminous flux transmitted through the axicon prism is reflected by the reflecting member and is incident again on the axicon prism, as described above, because the light beam transmitted through the two opposing axicon prisms arranged opposite to each other. Is equivalent to Moreover, in order for the emitted annular light flux to be parallel to the optical axis, the two axicon prisms must have the same refractive index and the same apex angle. However, when the reflecting member is disposed as in the above-described configuration, the incident light beam can be transmitted twice by one axicon prism, so that the axicon prism has a conventional apex angle no matter how many times. The transmission is the same as when two axicon prisms having the same refractive index and the same apex angle are used.

The orbicular luminous flux transmitted through the axicon prism and returned in the incident direction is separated by the light beam separating means.
It is separated from the collimated laser light (incident light beam).
As a result, only one axicon prism is required, and the processing accuracy of the apex angle is not necessarily required. As a result, the manufacturing cost is reduced.

Further, in order to make the optical axis of the incident light beam coincide with the optical axis of the outgoing light beam, only one axicon prism needs to be positioned, and assembly and adjustment can be easily performed, resulting in a reduction in cost.

Thus, a desired annular light beam can be obtained with a simple and inexpensive configuration. According to the illumination optical system of the second aspect of the present invention, it is particularly preferable that the interval between the axicon prism and the reflection member is configured to be variable in the optical axis direction.

With this configuration, it is easy to arbitrarily change the diameter of the annular light beam. According to the illumination optical system of the third aspect of the present invention, a reflection surface is formed on the bottom surface of the axicon prism, and the collimated laser light is converted into a diffused light beam having a conical surface, and reflected by the reflection surface. The axicon prism converts the light beam parallel to the optical axis into an annular shape obtained by transmitting through the axicon prism again, and the light beam parallel to the optical axis in the annular shape with respect to the collimated laser light. Light separating means for separating light.

In such an illumination optical system, the collimated laser light enters the axicon prism, is reflected by the reflection surface on the bottom of the axicon prism, and is transmitted again through the axicon rhythm and emitted. The light beam emitted from this axicon rhythm becomes a light beam having a ring shape parallel to the optical axis, and this light beam is separated from the collimated laser light by the light beam separating means.

According to the illumination optical system of the fourth aspect of the present invention, when a laser emitting linearly polarized light is used as the light source, the light beam separating means for separating the annular light beam from the collimated laser light is particularly required. , Polarizing beam splitter and 1 /
It is preferable to use a 4λ plate.

Here, the polarization beam splitter transmits the polarization of the P-direction component of the incident light and reflects the polarization of the S-direction component, so that the polarization direction of the linearly polarized light emitted from the laser is changed by the polarization beam splitter. When arranged so as to be parallel to the P direction of the reflection surface, all the linearly polarized light emitted from the laser passes through the polarization beam splitter.

Then, the linearly polarized light transmitted through the polarizing beam splitter is incident on a ４λ plate.
When the optical axis of the 4λ plate is arranged so as to face a predetermined direction,
Light transmitted through the λλ plate becomes circularly polarized light. The circularly polarized light enters the axicon prism as described above, is reflected by the reflection member, passes through the axicon prism again, becomes annular light, and is again guided to the ４λ plate.

The circularly polarized light that has re-entered the ４λ plate is converted into linearly polarized light whose polarization direction is rotated by 90 degrees with respect to the incident light, so that light of the S-direction component is incident on the polarization beam splitter. Is reflected.

As described above, the polarization beam splitter and the 1/4
By combining the λ plate, the incident light from the laser and
Since the annular light formed when the light is transmitted through the axicon prism twice can be separated, even if the inner diameter of the annular light is smaller than the outer diameter of the incident light, the annular light is It can be separated from incident light.

According to the illumination optical system of the fifth aspect of the present invention, the light beam separating means transmits the collimated laser beam to the axicon prism and converts the annular light beam converted by the axicon prism into a beam. It is preferable to use a perforated mirror that separates the collimated laser light.

With such an illumination optical system, the collimated laser light enters the axicon prism through the hole of the perforated mirror, is reflected by the reflecting member, and is converted into a ring-shaped light beam to form the hole. Returning to the empty mirror, the annular mirror separates the annular light beam from the collimated laser light.

According to the axicon prism of the sixth aspect of the present invention, the reflection surface is formed on the bottom surface of the axicon prism. With such an axicon prism, the collimated laser light enters the axicon prism, is reflected by the reflection surface on the bottom surface of the axicon prism, passes through the axicon rhythm again, and exits. The light beam emitted from the axicon rhythm becomes a diffuse light beam having a conical wavefront, and becomes a light beam parallel to the optical axis in an annular shape.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIGS. 1A and 1B are conceptual diagrams showing a configuration example of an illumination optical system according to the present embodiment. The same elements as those in FIG. ing.

That is, as shown in FIGS. 1 (a) and 1 (b), the illumination optical system of the present embodiment includes a polarizing beam splitter 2 and a quarter-wave plate (hereinafter, referred to as a quarter-λ plate) 4. Of light separating means, one axicon prism 6, and a mirror 8 as a reflecting member. The axicon prism 6 has a conical surface (conical surface) and a flat surface (bottom surface) opposite to the conical surface.

A laser light source (not shown) that emits linearly polarized light and the polarization beam splitter 2 are arranged such that the polarization direction of the linearly polarized light and the P direction on the opposite surface of the polarization beam splitter 2 are parallel.

Further, the λλ plate 4 is arranged such that the direction of the optical axis thereof is linearly polarized light in the P direction transmitted through the polarizing beam splitter 2 to be circularly polarized light. The linearly polarized light emitted from the laser light source passes through the polarization beam splitter 2, becomes circularly polarized light by the ４λ plate 4, enters the axicon prism 6, passes through the axicon prism 6, and then passes through the mirror 8. The light is reflected, and again the axicon prisms 6, 1
The light passes through the / 4λ plate 4 and becomes linearly polarized light having only the S-direction component with respect to the polarization beam splitter 2, and is reflected by the polarization beam splitter 2.

The axicon prism 6 has a function of converting the circularly polarized light emitted from the ４λ plate 4 into a diffused light beam having a conical wavefront. The mirror 8 has a function of reflecting the diffused light beam having a conical surface converted by the axicon prism 6 and causing the light to enter the axicon prism 6 again.

The light beam reflected by the mirror 8 passes through the axicon prism 6 again, so that the light beam is in the above-mentioned annular shape and is parallel to the optical axis. on the other hand,
In the present embodiment, as shown in FIG. 1B, the distance between the axicon prism 6 and the mirror 8 is configured to be variable in the optical axis direction.

Next, the operation of the illumination optical system according to the first embodiment configured as described above will be described. Fig. 1 (a)
, A collimated light beam emitted from a laser light source (not shown) passes through the polarizing beam splitter 2 and
The light is converted into circularly polarized light by the / 4λ plate 4 and is incident on the axicon prism 6.

The light beam incident on the axicon prism 6 is
The light becomes a diffused light beam having a conical wavefront, is reflected by the mirror 8, and is incident on the axicon rhythm 6 again. In this case, the light beam transmitted through the axicon prism 6 is reflected by the mirror 8
Is reflected by the axicon prism 6 and is incident again on the axicon prism 6, as shown by the broken line in FIG. Of light.

When the zonal light beam transmitted through the axicon prism 6 passes through the １ ／ λ plate 4 again, its polarization direction is rotated by 90 degrees with respect to the incident light, so that it is reflected by the polarization beam splitter 2. Then, the light is separated from a collimated light beam (incident light beam) emitted from a laser light source (not shown).

Further, in this case, the axicon prism 6
Is transmitted twice, so that the light flux is always parallel to the optical axis regardless of the apex angle of the axicon prism 6. Therefore, if the optical axis of the axicon prism 6 matches the optical axis of the incident collimated light, The optical axis of the annular light flux also coincides with the optical axis of the incident collimated light.

Further, as shown in FIG. 1B, by changing the distance between the axicon prism 6 and the mirror 8, the diameter of the annular light beam can be changed arbitrarily. As described above, the illumination optical system according to the first embodiment includes one axicon prism 6 that converts the collimated laser light into a diffused light beam having a conical wavefront;
A mirror 8 for reflecting a diffused light beam having a conical wavefront converted by the axicon prism 6, and an annular shape parallel to the optical axis which is reflected by the mirror 8 and transmitted through the axicon prism 6 again. The light beam is composed of a collimated laser beam and a polarizing beam splitter 2 for separating the collimated laser beam and a light beam separating means including a λλ plate 4.

Accordingly, only one axicon prism 6 is required, and the processing accuracy of the apex angle is not necessarily required.
As a result, manufacturing costs are reduced. Further, in order to make the optical axis of the incident light beam coincide with the optical axis of the outgoing light beam, only one axicon prism 6 and mirror 8 need to be positioned, and assembling and adjustment can be performed easily. As a result, the cost is reduced.

As a result, a desired annular light beam can be obtained with a simple and inexpensive configuration. Further, since the distance between the axicon prism 6 and the mirror 8 is configured to be variable in the optical axis direction, it is easy to arbitrarily change the diameter of the annular light flux.

Further, the polarization beam splitters 2 and 1/4
Since the annular light beam is separated from the collimated laser light by the λ plate 4, even if the inner diameter of the annular light beam is smaller than the incident light, the annular light beam can be separated from the incident light. Becomes possible.

(Second Embodiment) FIG. 2 is a conceptual diagram showing an example of the configuration of an illumination optical system according to a second embodiment.
The same elements as those in FIG. 1 are denoted by the same reference numerals.

That is, as shown in FIG. 2, the illumination optical system according to the present embodiment has a perforated mirror 1 serving as a light beam separating means.
0, one axicon prism 6 and a mirror 8 as a reflection member.

The perforated mirror 10 has a function of separating a light beam, which is parallel to the optical axis and has a ring shape described later, from a light beam emitted from a collimated laser light source (not shown).

The axicon prism 6 has a perforated mirror 1
It has a function of converting a light beam passing through 0 into a diffuse light beam having a conical wavefront. The mirror 8 has a function of reflecting the diffused light beam having a conical wavefront converted by the axicon prism 6 and causing the light beam to enter the axicon prism 6 again.

In the same manner as described above, the light beam reflected by the mirror 8 is transmitted through the axicon prism 6 again, so that it becomes a light beam in the above-mentioned annular shape parallel to the optical axis.

Here, the inner diameter of the perforated mirror 10 is formed to be larger than the diameter of the incident light beam and smaller than the inner diameter of the annular light beam. Next, the operation of the illumination optical system according to the second embodiment configured as described above will be described.

In FIG. 2, a collimated light beam emitted from a laser light source (not shown) passes through a perforated mirror 10 and is incident on an axicon prism 6. The light beam incident on the axicon prism 6 becomes a diffuse light beam having a conical wavefront, is reflected by the mirror 8, and is again incident on the axicon rhythm 6.

In this case, the light beam transmitted through the axicon prism 6 is reflected by the mirror 8 and
Again. Since this is equivalent to transmitting the same two axicon prisms arranged opposite to each other as described above, the light flux becomes a ring-shaped light flux.

The orbicular light beam transmitted through the axicon prism 6 is reflected by the perforated mirror 10 and separated from the collimated light beam (incident light beam) emitted from a laser light source (not shown).

Further, in this case, the axicon prism 6
Is transmitted twice, so that the light flux is always parallel to the optical axis regardless of the apex angle of the axicon prism 6. Therefore, if the optical axis of the axicon prism 6 matches the optical axis of the incident collimated light, The optical axis of the annular light flux also coincides with the optical axis of the incident collimated light.

Also, by changing the distance between the axicon prism 6 and the mirror 8 as described above, the diameter of the orbicular light beam can be changed arbitrarily. As described above, the illumination optical system according to the second embodiment includes one axicon prism 6 for converting the collimated laser beam into a diffused light beam having a conical wavefront, and the axicon prism 6 for conversion. A mirror 8 for reflecting the diffused light beam having the conical wavefront, and an orbicular light beam parallel to the optical axis, which is reflected by the mirror 8 and transmitted again through the axicon prism 6, is collimated. And a perforated mirror 10 for separating the laser beam from the laser beam.

Therefore, only one axicon prism 6 is required, and the machining accuracy of the apex angle is not necessarily required.
As a result, manufacturing costs are reduced. Further, in order to make the optical axis of the incident light beam coincide with the optical axis of the outgoing light beam, only one axicon prism 6 and mirror 8 need to be positioned, and assembling and adjustment can be performed easily. As a result, the cost is reduced.

As a result, a desired annular light beam can be obtained with a simple and inexpensive configuration. Further, since the distance between the axicon prism 6 and the mirror 8 is configured to be variable in the optical axis direction, it is easy to arbitrarily change the diameter of the annular light flux.

The axicon prism 6 may be arranged so that the conical surface faces the mirror 8. (Third Embodiment) FIG. 3 is a conceptual diagram showing a configuration example of an illumination optical system according to a third embodiment. The same elements as those in FIG. I do.

This illumination optical system comprises a light beam splitting means comprising a polarizing beam splitter 2 and a 1 / 4.lambda. Plate 4, and an axicon prism 11 having a reflecting surface, for example, a mirror coating 12 on its bottom surface. Have been.

Among them, the axicon prism 11 is disposed with the apex angle directed toward the ４λ plate 4 side, receives the circularly polarized light emitted from the ４λ plate 4 and receives the mirror coating 1 on the bottom surface.
2 and has a function of converting the emitted circularly polarized light into a diffused light beam having a conical wavefront.

Next, the operation of the illumination optical system according to the third embodiment configured as described above will be described. The collimated light beam emitted from the laser light source passes through the polarization beam splitter 2, is converted into circularly polarized light by the λλ plate 4, and is incident on the axicon prism 11.

The axicon prism 11 converts the incident circularly polarized light into a mirror coating 12 formed on its bottom surface.
And converts the circularly polarized light into a diffused light beam having a conical wavefront and emits it.

As described above, the light beam transmitted through the inside of the axicon prism 11 is reflected by the mirror coating 12,
Transmission through the axicon prism 11 again is as shown in FIG.
As indicated by the broken line, the light beam is equivalent to passing through the same two axicon prisms arranged opposite to each other, so that the light beam has a ring-like shape.

The zonal luminous flux transmitted through the axicon prism 11 is reflected by the polarization beam splitter 2 because the polarization direction of the luminous flux is rotated by 90 degrees with respect to the incident light when the luminous flux is transmitted again through the ４λ plate 4. Then, it is separated from a collimated light beam (incident light beam) emitted from a laser light source (not shown).

Further, in this case, the axicon prism 6
Is transmitted twice, so that the light flux is always parallel to the optical axis regardless of the apex angle of the axicon prism 11. Therefore, if the optical axis of the axicon prism 11 matches the optical axis of the incident collimated light, The optical axis of the annular light flux also coincides with the optical axis of the incident collimated light.

As described above, in the illumination optical system of the third embodiment, the mirror coating 12 is applied to the bottom of the axicon prism, and the collimated laser light is converted into a diffused light having a conical wavefront. Axicon prism 11 and a polarized beam that separates, from collimated laser light, a luminous flux that is reflected by the mirror coating 12 and that is parallel to the optical axis and that is obtained by passing through the axicon prism 11 again. The beam splitter comprises a splitter 2 and a ４λ plate and a beam splitting means with four beam splitting means.

Therefore, similarly to the first embodiment,
Only one axicon prism 11 is required, and the processing accuracy of the apex angle is not always necessary, and as a result, the manufacturing cost is reduced. Further, in order to make the optical axis of the incident light beam coincide with the optical axis of the outgoing light beam, it is only necessary to position one axicon prism 11, and assembly and adjustment can be easily performed, resulting in a reduction in cost.

Thus, it is possible to obtain a desired annular light beam with a simple and inexpensive configuration. Further, the annular beam is separated from the collimated laser beam by the polarization beam splitter 2 and the λλ plate 4, so even if the inner diameter of the annular beam is smaller than the incident light, It is possible to separate the belt-like light beam from the incident light.

(Fourth Embodiment) FIG. 3 is a conceptual diagram showing a configuration example of an illumination optical system according to a fourth embodiment.
The same elements as those in FIG. 1 are denoted by the same reference numerals, and a detailed description thereof will be omitted.

On the optical axis of the laser beam, a perforated mirror 13 is provided.
Is arranged. The perforated mirror 13 is reflected by the mirror coating 12 of the axicon prism 11,
It has a function as a light beam separating means for separating a light flux having an annular shape and being parallel to the optical axis, which is obtained by transmitting the light again through the axicon prism 11, to the collimated laser light.

Next, the operation of the illumination optical system according to the fourth embodiment configured as described above will be described. The collimated light beam emitted from the laser light source passes through the hole of the perforated mirror 13 and enters the axicon prism 11.

The axicon prism 11 reflects the incident light beam on the mirror coating 12 formed on the bottom surface thereof, and converts the light beam into a diffused light beam having a conical wavefront and emits the light beam.

The light beam transmitted through the inside of the axicon prism 11 is reflected by the mirror coating 12 and transmitted through the axicon prism 11 again, so that the light beam is transmitted through two identical axicon prisms arranged opposite to each other. This is equivalent to a ring-shaped light flux.

The annular luminous flux emitted from the axicon prism 11 is reflected by the mirror portion of the perforated mirror 13 and separated from the collimated laser light. In this case, since the light passes through the axicon prism 11 twice,
Since the light flux is always parallel to the optical axis regardless of the apex angle of the axicon prism 11, if the optical axis of the axicon prism 11 matches the optical axis of the incident collimated light, the optical axis of the annular light flux Also coincides with the optical axis of the incident collimated light.

As described above, in the illumination optical system of the fourth embodiment, the mirror coating 12 is applied to the bottom of the axicon prism, and the collimated laser light is converted into a diffused light having a conical wavefront. An axicon prism 11 and a perforated mirror 13 for separating a light flux parallel to the optical axis in an annular shape obtained by the axicon prism 11 are separated from collimated laser light. Therefore, it goes without saying that the illumination optical system according to the fourth embodiment has the same effects as those of the third embodiment.

[0072]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment to which the present invention is applied will be described in detail with reference to the drawings. FIG. 5 shows that the illumination optical system according to the present invention has a confocal laser scanning microscope (C
FIG. 3 is a configuration diagram illustrating an embodiment when applied to LSM).

In this embodiment, the case where the above-described perforated mirror 10 is used as the light beam separating means of the illumination optical system will be described, and the same elements as those in FIG. 2 are denoted by the same reference numerals.

In FIG. 5, a collimated light beam emitted from a laser light source (not shown) passes through a perforated mirror 10 and is incident on an axicon prism 6. The light beam incident on the axicon prism 6 becomes a diffuse light beam having a conical wavefront, is reflected by the mirror 8, and is again incident on the axicon rhythm 6.

The orbicular light beam transmitted through the axicon prism 6 is reflected by the perforated mirror 10 and separated from the collimated light beam (incident light beam) emitted from a laser light source (not shown).

In this case, the inner diameter of the perforated mirror 10 is larger than the diameter of the incident light beam and smaller than the inner diameter of the annular light beam. For this reason, the orbicular luminous flux reflected by the perforated mirror 10 is changed by the beam reducer 15 without changing the degree of orbicularity (ratio between the inner and outer diameters of the orbicular luminous flux) and only the outer diameter of the objective lens 28 is changed. The light is converted into a predetermined diameter so as to fill the pupil, passes through the beam splitter 14, and enters the first optical deflector 16 (hereinafter, simply referred to as the optical deflector 16).

The optical deflector 16 is arranged at a position conjugate with the pupil 30 of the objective lens 28. Therefore,
When the light deflector 16 is not deflecting, the orbicular luminous flux travels along the optical axis.

When the light deflector 16 is deflecting, that is, when scanning an annular light beam, the light deflector 16 is provided at the position of the pupil 30. Coincides with the off-axis chief ray.

Next, these annular light fluxes pass through the respective pupil transmission lenses 18 and 20 and enter a second optical deflector 22 (hereinafter simply referred to as an optical deflector 22) disposed at the pupil position. Is done.

It is assumed that the optical deflector 22 is configured to perform scanning in the X direction and the optical deflector 16 is configured to perform scanning in the Y direction among the two-dimensional scanning. The light beam two-dimensionally scanned by the light deflector 16 and the light deflector 22 is
The light enters the pupil 30 of the objective lens 28 by the pupil projection lens 24 and the imaging lens 26.

Then, the annular luminous flux generates a point light which is limited by being diffracted onto the sample 32 by the objective lens 28. Further, the light deflector 16 and the light deflector 22 are
By performing the XY two-dimensional scanning, the point light is changed to the sample 3.
2 is scanned two-dimensionally.

The light beam reflected from the sample 32 passes through the objective lens 28 and its pupil 30, and further passes through the image forming lens 26.
Is imaged once. This imaging surface is a surface on which an image is observed with a normal optical microscope. Further, the light beam returns to the light deflector 22 by the pupil projection lens 24.

As described above, the reflected beam returns to the beam splitter 14 through the exactly same path as when it entered the sample 32, and is taken out by the beam splitter 14. In this case, the reflected beam passes through the pupil 30 of the objective lens 28.
Since the light beam returns after passing through the optical deflectors 16 and 22 arranged at positions conjugate with the above, the detection beam does not move even when scanning is performed off-axis.

Then, the detection beam is narrowed down to a point by the condenser lens 34, a pinhole 36 is provided at the position narrowed down to a point, and a detector 38 behind the pinhole 36 detects the detection beam. An image with a higher resolution and a longer focal depth can be obtained than with a scanning microscope (CLSM).

Here, if the apex angle of the axicon prism 6 varies due to the processing accuracy, the diameter of the orbicular luminous flux changes. Even in such a case, the distance between the axicon prism 6 and the mirror 8 is changed. Is variable, the outer diameter of the annular luminous flux can be easily adjusted to the pupil diameter of the objective lens 28.

Further, in such a microscope system,
In general, a plurality of objective lenses are arranged on a revolver and can be switched. Similarly, by changing the distance between the axicon prism 6 and the mirror 8, the outer diameter of the orbicular light beam is adjusted to the pupil of each objective lens. Can be adjusted to the diameter.

The present invention is not limited to the first to fourth embodiments, but may be modified as follows. In the above-described embodiment, the case where the illumination optical system according to the second embodiment is applied to a confocal laser scanning microscope has been described. However, the present invention is not limited to this, and the first, third, and fourth embodiments are not limited thereto.
The illumination optical system described in the embodiment may be applied to a confocal laser scanning microscope.

In the above embodiment, the hole of the perforated mirror 10 is made larger than the incident light and smaller than the inner diameter of the annular light beam so that the incident light is transmitted and the annular light beam is reflected. However, a mirror larger than the incident light and smaller than the inner diameter of the annular light flux may reflect the incident light and transmit the annular light flux.

[0089]

As described above, according to the illumination optical system of the present invention, only one axicon prism is required, and the processing accuracy of the apex angle is not necessarily required, and as a result, the manufacturing cost is reduced. . In addition, in order to make the optical axis of the incident light beam coincide with the optical axis of the outgoing light beam, only one axicon prism needs to be positioned, and assembly and adjustment can be easily performed.
As a result, costs are reduced.

As a result, a desired annular light beam can be obtained with a simple and inexpensive configuration. According to the illumination optical system of the present invention, the distance between the axicon prism and the reflecting member is configured to be variable in the optical axis direction, so that it is easy to arbitrarily change the diameter of the annular light flux. Become.

According to the axicon prism of the present invention, since the reflection surface is formed on the bottom surface of the axicon prism,
An annular light beam can be obtained with one axicon prism.

Further, according to the illumination optical system of the present invention, the light beam separating means for separating the annular light beam from the collimated laser light is constituted by the polarizing beam splitter and the λλ plate, so that the annular optical beam is temporarily provided. Even when the inner diameter of the light beam is smaller than the incident light, the annular light beam can be separated from the incident light.

Further, according to the illumination optical system of the present invention, the light beam separating means for separating the annular light beam from the collimated laser light is constituted by a perforated mirror, if the inner diameter of the annular light beam is smaller than the incident light. However, the annular light beam can be separated from the incident light.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a first embodiment of an illumination optical system according to the present invention.

FIG. 2 is a conceptual diagram showing a second embodiment of the illumination optical system according to the present invention.

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

FIG. 4 is a conceptual diagram showing a fourth embodiment of the illumination optical system according to the present invention.

FIG. 5 is a configuration diagram showing an embodiment when the illumination optical system according to the present invention is applied to a confocal laser scanning microscope (CLSM).

FIG. 6 is a schematic diagram illustrating a configuration example of a conventional illumination optical system for forming annular light.

[Explanation of symbols]

 2: polarizing beam splitter, 4: 1/4 λ plate, 6: axicon prism, 8: mirror, 10: perforated mirror, 11: axicon prism, 12: mirror coating, 13: perforated mirror, 15: beam reducer , 14: beam splitter, 16, 22: optical deflector, 18, 20: pupil transmission lens, 24: pupil projection lens, 26: imaging lens, 28: objective lens, 30: pupil position of objective lens, 32: sample , 34: condenser lens, 36: pinhole, 38: detector.

Claims (6)

[Claims] 1. An axicon prism for converting a collimated laser beam into a diffused light beam having a conical wavefront, and a reflection reflecting the diffused light beam having a conical wavefront converted by the axicon prism. A member, a light beam separating means for separating a light flux parallel to the optical axis in an annular shape obtained by transmitting through the axicon prism again, which is reflected by the reflecting member, from the collimated laser light; An illumination optical system comprising: 2. The illumination optical system according to claim 1, wherein a distance between the axicon prism and the reflection member is variable in an optical axis direction. 3. A reflecting surface is formed on the bottom surface of the axicon prism, and the collimated laser light is converted into a diffused light beam having a conical wavefront, reflected by the reflecting surface, and transmitted through the axicon prism again. An axicon prism for converting into a light flux parallel to the optical axis in an annular shape obtained by performing the above, a light beam separating means for separating the light flux parallel to the optical axis in the annular shape from the collimated laser light, An illumination optical system comprising: 4. The illumination optical system according to claim 1, wherein said light beam splitting means comprises a polarizing beam splitter and a quarter-wave plate. 5. The light beam separating means transmits the collimated laser light through the axicon prism and converts the orbicular light beam converted by the axicon prism into the collimated laser light. 4. The illumination optical system according to claim 1, wherein the illumination optical system is constituted by a perforated mirror which separates the illumination optical system from the illumination light. 6. An axicon prism, wherein the bottom surface of the axicon prism is a reflection surface.