Observation device

1. An observation device comprising:

an illuminating optical system;

an objective optical system; and

a reflection member,

wherein the illuminating optical system emits illuminating light obliquely upward with respect to an optical axis of the objective optical system from below a sample,

the reflection member reflects, above the sample, the illuminating light emitted from the illuminating optical system,

the objective optical system obtains an image of transmitted light, which has been reflected by the reflection member, has passed through the sample, and has been incident on the sample obliquely with respect to the optical axis of the objective optical system, the objective optical system obtaining the image of the transmitted light below the sample and via a different path from the illuminating optical system,

the illuminating optical system includes:

a light source;

a mask that restricts light, which is emitted from the light source, to a particular emission region, the mask having one aperture at a center thereof, a center of a light beam of the illuminating light, which is projected onto a pupil plane of the objective optical system, from the mask being eccentric with respect to a center of the optical axis of the objective optical system; and

a collimating optical system that converts the light restricted by the mask into substantially parallel light, and

the illuminating optical system is arranged so that when the emission region is projected onto a pupil plane of the objective optical system, a projected image of the emission region partially overlaps a peripheral portion of the pupil.

2. The observation device according to claim 1 , wherein conditional formula (1) is satisfied:

0.05 ≤d/D≤ 0.4  (1)

where D is a pupil diameter of the objective optical system, and d is a light beam diameter when the emission region is projected onto the pupil plane.

3. The observation device according to claim 1 , wherein conditional formula (2) is satisfied:

0.1≤ ds /( NAo·Fi )≤0.8  (2)

where ds is a size of the emission region in a direction in which illuminating light emitted from the illuminating optical system is inclined, Fi is a focal length of the collimating optical system, and NAo is a numerical aperture on the sample side of the objective optical system.

4. The observation device according to claim 1 , wherein conditional formula (3) is satisfied:

NAo−ds·Fi/ 2 Fop 2 ≤θ≤NAo+ds·Fi/ 2 Fop 2   (3)

where ds is a size of the emission region in a direction in which illuminating light emitted from the illuminating optical system is inclined, Fi is a focal length of the collimating optical system, NAo is a numerical aperture on the sample side of the objective optical system, Fop is a focal length from on the sample side of the pupil of the objective optical system, and θ is an inclination angle of the illuminating light, which has been converted into substantially parallel light by the collimating optical system, with respect to an optical axis of the objective optical system and at a position of the sample.

5. The observation device according to claim 1 , wherein the emission region has a shape that constitutes a part of a ring.

6. The observation device according to claim 5 , wherein the mask includes a light attenuation portion in which transmittance decreases continuously or in a stepwise manner toward a radially inner side, the light attenuation portion being disposed inside the emission region.

7. The observation device according to claim 5 , wherein the mask includes a light attenuation portion in which transmittance increases continuously or in a stepwise manner toward a radially inner side, the light attenuation portion being disposed inside the emission region.

8. The observation device according to claim 1 , wherein the sample is contained in a container which comprises an optically transparent material and includes a top plate above the sample, the top plate reflecting at least a part of light to serve as the reflection member.

9. An observation device comprising:

an illuminating optical system that emits illuminating light obliquely upward from below a sample;

a reflection member that reflects, above the sample, the illuminating light emitted from the illuminating optical system; and

an objective optical system that images transmitted light, which has been reflected by the reflection member, and has passed through the sample, the objective optical system imaging the transmitted light below the sample and via a different path from the illuminating optical system,

wherein the illuminating optical system includes a light source, a mask that restricts light, which is emitted from the light source, to a particular emission region, and a collimating optical system that converts the light restricted by the mask into substantially parallel light,

the illuminating optical system is arranged so that when the emission region is projected onto a pupil plane of the objective optical system, a projected image of the emission region partially overlaps a peripheral portion of the pupil; and

conditional formula 0.05≤d/D≤0.4 is satisfied:

where D is a pupil diameter of the objective optical system, and d is a light beam diameter when the emission region is projected onto the pupil plane.

10. An observation device comprising:

an illuminating optical system that emits illuminating light obliquely upward from below a sample;

a reflection member that reflects, above the sample, the illuminating light emitted from the illuminating optical system; and

an objective optical system that images transmitted light, which has been reflected by the reflection member, and has passed through the sample, the objective optical system imaging the transmitted light below the sample and via a different path from the illuminating optical system,

wherein the illuminating optical system includes a light source, a mask that restricts light, which is emitted from the light source, to a particular emission region, and a collimating optical system that converts the light restricted by the mask into substantially parallel light,

the illuminating optical system is arranged so that when the emission region is projected onto a pupil plane of the objective optical system, a projected image of the emission region partially overlaps a peripheral portion of the pupil; and

conditional formula 0.1≤ds/(NAo·Fi)≤0.8 is satisfied:

where ds is a size of the emission region in a direction in which illuminating light emitted from the illuminating optical system is inclined, Fi is a focal length of the collimating optical system, and NAo is a numerical aperture on the sample side of the objective optical system.

11. An observation device comprising:

an illuminating optical system that emits illuminating light obliquely upward from below a sample;

a reflection member that reflects, above the sample, the illuminating light emitted from the illuminating optical system; and

an objective optical system that images transmitted light, which has been reflected by the reflection member, and has passed through the sample, the objective optical system imaging the transmitted light below the sample and via a different path from the illuminating optical system,

wherein the illuminating optical system includes a light source, a mask that restricts light, which is emitted from the light source, to a particular emission region, and a collimating optical system that converts the light restricted by the mask into substantially parallel light,

the illuminating optical system is arranged so that when the emission region is projected onto a pupil plane of the objective optical system, a projected image of the emission region partially overlaps a peripheral portion of the pupil; and

conditional formula NAo−ds·Fi/2Fop 2 ≤θ≤NAo+ds·Fi/2Fop 2 is satisfied:

where ds is a size of the emission region in a direction in which illuminating light emitted from the illuminating optical system is inclined, Fi is a focal length of the collimating optical system, NAo is a numerical aperture on the sample side of the objective optical system, Fop is a focal length from on the sample side of the pupil of the objective optical system, and θ is an inclination angle of the illuminating light, which has been converted into substantially parallel light by the collimating optical system, with respect to an optical axis of the objective optical system and at a position of the sample.

12. An observation device comprising:

an illuminating optical system that emits illuminating light obliquely upward from below a sample;

a reflection member that reflects, above the sample, the illuminating light emitted from the illuminating optical system; and

an objective optical system that images transmitted light, which has been reflected by the reflection member, and has passed through the sample, the objective optical system imaging the transmitted light below the sample and via a different path from the illuminating optical system,

wherein the illuminating optical system includes a light source, a mask that restricts light, which is emitted from the light source, to a particular emission region, and a collimating optical system that converts the light restricted by the mask into substantially parallel light,

the illuminating optical system is arranged so that when the emission region is projected onto a pupil plane of the objective optical system, a projected image of the emission region partially overlaps a peripheral portion of the pupil; and

the emission region has a shape that constitutes a part of a ring.

13. The observation device according to claim 12 , wherein the mask includes a light attenuation portion in which transmittance decreases continuously or in a stepwise manner toward a radially inner side, the light attenuation portion being disposed inside the emission region.

14. The observation device according to claim 12 , wherein the mask includes a light attenuation portion in which transmittance increases continuously or in a stepwise manner toward a radially inner side, the light attenuation portion being disposed inside the emission region.

15. An observation device comprising:

an illuminating optical system that emits illuminating light obliquely upward from below a sample;

a reflection member that reflects, above the sample, the illuminating light emitted from the illuminating optical system; and

an objective optical system that images transmitted light, which has been reflected by the reflection member, and has passed through the sample, the objective optical system imaging the transmitted light below the sample and via a different path from the illuminating optical system,

wherein the illuminating optical system includes a light source, a mask that restricts light, which is emitted from the light source, to a particular emission region, and a collimating optical system that converts the light restricted by the mask into substantially parallel light,

the illuminating optical system is arranged so that when the emission region is projected onto a pupil plane of the objective optical system, a projected image of the emission region partially overlaps a peripheral portion of the pupil; and

the sample is contained in a container which comprises an optically transparent material and includes a top plate above the sample, the top plate reflecting at least a part of light to serve as the reflection member.