Microscope and microscope image acquisition method

1. A microscope comprising:

a detection optical system that detects fluorescence emitted from a specimen to acquire a fluorescence image;

a light-sheet illumination optical system that causes planar excitation light to be incident along a direction intersecting an optical axis of the detection optical system; and

an image processing section that processes the fluorescence image acquired by the detection optical system,

wherein:

the light-sheet illumination optical system moves a focal position of the excitation light along an incidence direction thereof,

the image processing section combines a plurality of fluorescence images that are acquired by the detection optical system, each of the plurality of fluorescence images being acquired with the excitation light being made incident on a different focal position by the light-sheet illumination optical system, to generate a composite image, and

the image processing section, in combining the plurality of the fluorescence images, compares luminance values or contrast values of corresponding pixels in the fluorescence images and selects a pixel having a maximum luminance value or a maximum contrast value.

2. The microscope according to claim 1 , wherein the light-sheet illumination optical system can set a movement start position, a number of movement steps, and a displacement of each movement step for the focal position of the excitation light.

3. The microscope according to claim 2 , wherein the light-sheet illumination optical system can switch a wavelength of the excitation light and can set the movement start position and the displacement for each wavelength of the excitation light.

4. The microscope according to claim 1 , wherein the light-sheet illumination optical system can cause the excitation light to be incident alternately from two or more different directions from outside the specimen.

5. The microscope according to claim 4 , wherein the light-sheet illumination optical system can cause the excitation light to be incident from opposite sides with respect to the optical axis of the detection optical system.

6. The microscope according to claim 1 , further comprising a control section that, when a magnification of the detection optical system is raised, controls the light-sheet illumination optical system so as to reduce a radiation width of the excitation light to be made incident on the specimen by the light-sheet illumination optical system.

7. The microscope according to claim 6 , wherein the light-sheet illumination optical system includes:

an excitation-light-forming optical system that forms the planar excitation light, the planar excitation light having a predetermined width; and

a scanning section that scans the planar excitation light formed by the excitation-light-forming optical system in a width direction of the planar excitation light, and

wherein the control section controls a swivel angle of the scanning section.

8. The microscope according to claim 4 , wherein the light-sheet illumination optical system includes:

an illumination-direction switching section that alternately switches the incidence direction between two or more different directions from outside the specimen to sequentially cause the excitation light to be incident along a plane intersecting the optical axis of the detection optical system,

wherein the image processing section combines the plurality of fluorescence images that are acquired by the detection optical system, each of the plurality of fluorescence images being acquired with the excitation light being made incident along one of the two or more different directions, and

wherein the light-sheet illumination optical system switches the incidence direction of the excitation light in such an order that the excitation light is made incident starting from a same direction as a last direction that the excitation light was made incident in a most recent combining processing by the image processing section.

9. The microscope according to claim 4 , further comprising:

an illumination-direction switching section that alternately switches the incidence direction between two or more different directions from outside the specimen to sequentially cause the planar excitation light to be incident along a plane intersecting the optical axis of the detection optical system;

a movement mechanism that moves the specimen in an optical-axis direction of the detection optical system; and

a control section that controls the illumination-direction switching section and the movement mechanism,

wherein the image processing section combines the plurality of fluorescence images that are acquired by the detection optical system, each of the plurality of fluorescence images being acquired with the excitation light being made incident along one of the two or more different directions, and

wherein when fluorescence images based on the planar excitation light that is made incident along each of the two or more different directions are acquired for one position in the optical-axis direction, the control section controls the movement mechanism so as to move the specimen to a different position in the optical-axis direction and controls the illumination-direction switching section so as to switch the incidence direction of the excitation light in such an order that the excitation light is made incident starting from a same direction as a last direction that the excitation light was made incident before movement of the specimen by the movement mechanism.