Image obtaining unit and image obtaining method

1. An image obtaining apparatus, comprising:

an image sensor configured to form an image;

an optical system configured to:

apply excitation light from a light source to at least a partial area of a biological sample, the part including a fluorescent label, and

cause the image sensor to form a fluorescent image of the partial area;

a movement control unit configured to

move a focal position of the optical system to an optical axis direction of the optical system and a direction perpendicular to the optical axis;

a generation unit configured to:

continuously expose the image sensor during the movement of the focal position of the optical system, and

generate an image of the partial area; and

a calculation unit configured to

analyze spatial frequency of the generated image, and

calculate positional information in the optical axis direction of the fluorescent label by using at least results of the analysis,

obtain moving images by moving the generated image by one or more pixels set in advance in one or more directions,

obtain a correlation between the generated image and each of the obtained moving images, and

determine one of the one or more directions of one of the obtained moving images having lowest correlation.

2. The image obtaining apparatus according to claim 1 , wherein the calculation unit is configured to:

analyze the spatial frequency of the generated image in at least one direction of the one or more directions, wherein the at least one direction is different from two directions set in advance, the two directions being perpendicular to each other,

determine one of the directions, which has highest spatial frequency, and

calculate the positional information based on the determined one of the directions.

3. The image obtaining apparatus according to claim 2 , wherein the calculation unit is configured to

store information of the obtained correlation and the positional information in advance, and

calculate the positional information from the determined one of the directions based on the obtained information of the obtained correlation.

4. An image obtaining method, comprising:

generating excitation light causing a fluorescent label of a biological sample to emit light;

applying the generated excitation light to at least a partial area of the biological sample, the part including the fluorescent label, and causing an image sensor to form a fluorescent image of the partial area by an optical system;

moving a focal position of the optical system to an optical axis direction of the optical system and a direction perpendicular to the optical axis;

continuously exposing the image sensor during the movement of the focal position of the optical system, and generating an image of the partial area;

analyzing spatial frequency of the generated image, and calculating positional information in the optical axis direction of the fluorescent label by using at least results of the analysis;

obtaining moving images by moving the generated image by one or more pixels set in advance in one or more directions;

obtaining a correlation between the generated image and each of the obtained moving images, and

determining one of the one or more directions of the obtained moving images having lowest correlation.

5. An image obtaining method, comprising:

generating excitation light causing a fluorescent label of a biological sample to emit light;

applying the generated excitation light to at least a partial area of the biological sample, the part including the fluorescent label, and causing an image sensor to form a fluorescent image of the partial area by an optical system;

moving a focal position of the optical system to an optical axis direction of the optical system and a direction perpendicular to the optical axis;

continuously exposing the image sensor during the movement of the focal position of the optical system, and generating plurality of images of the partial area;

analyzing spatial frequency of each of the generated plurality of images to determine maximum spatial frequency,

comparing the determined maximum spatial frequency of each of the generated plurality of images with each other, and

selecting an image having the maximum spatial frequency from the generated plurality of images.

6. The image obtaining method according to claim 5 , further comprising

analyzing an image of locus of a fluorescent marker in the selected image having the maximum spatial frequency to determine distribution information of the fluorescent marker.

7. The image obtaining method according to claim 6 , wherein

the fluorescent marker is a bright spot of a predetermined color labeled on the biological sample.

8. The image obtaining method according to claim 7 , further comprising

detecting the shape and number of fluorescent markers based on the color of each of the fluorescent markers.