Focusing method, measuring method, principal point detecting method, focusing device, measuring device, and principal point detecting device

A focusing method comprising:

• a step of preparing a microscope including an illumination optical system and an observation optical system, the illumination optical system includes a condenser lens, the observation optical system includes an objective lens, in the step of preparing, a partial region of illumination light is shielded or darkened by an aperture, wherein the aperture is between the condenser lens and a light source;
• a step of mounting a sample having a surface shape that is curved, on the microscope, in the step of mounting, the sample and the observation optical system are opposed to each other in a state in which the surface shape of the sample is not deformed;
• and
• a predetermined processing step, the predetermined processing step comprising:
• a step of receiving light emitted from the observation optical system;
• a step of obtaining a quantity of light based on light from a predetermined region of the received light, the predetermined region is a partial region of the sample;
• a step of calculating a difference or a ratio between the quantity of light in the predetermined region and a quantity of light as a reference;
• a step of comparing a calculation result with a threshold;
• and
• a step of changing a distance between the sample and the observation optical system,
• when the calculation result is equal to or smaller than the threshold, the predetermined processing step is terminated,
• following conditional expression is satisfied:
• 0.6≤(R0×β)/Rob<0.995
• where
• R0 is a length from an optical axis of the illumination optical system to an outer edge of the partial region of illumination light;
• Rob is a radius of a pupil of the objective lens;
• and
• β is a value obtained by dividing a focal length of the objective lens by a focal length of the condenser lens.

A focusing method comprising:

• a step of preparing a microscope including an illumination optical system and an observation optical system, in the step of preparing, a partial region of illumination light is shielded or darkened by an aperture, wherein a first region is the partial region of illumination light, a second region is formed outside the first region with a region interposed therebetween to allow the illumination light to pass through, and shields or darkens part of the illumination light, an image of an outer edge of the first region is formed inside an outer edge of a pupil of the observation optical system, and an image of an inner edge of the second region is formed outside the outer edge of the pupil of the observation optical system, wherein the aperture is between a light source of the illumination light and a sample;
• a step of mounting a sample having a surface shape that is curved, on the microscope, in the step of mounting, the sample and the observation optical system are opposed to each other in a state in which the surface shape of the sample is not deformed;
• and
• a predetermined processing step, the predetermined processing step comprising:
• a step of receiving light emitted from the observation optical system,
• a step of obtaining a quantity of light based on light from a predetermined region of the received light, the predetermined region is a partial region of the sample,
• a step of calculating a difference or a ratio between the quantity of light in the predetermined region and a quantity of light as a reference,
• a step of comparing a calculation result with a threshold, and
• a step of changing a distance between the sample and the observation optical system,
• when the calculation result is equal to or smaller than the threshold, the predetermined processing step is terminated.

A focusing device comprising:

• an illumination optical system;
• an observation optical system;
• a holding member;
• a drive device;
• a light-receiving device;
• and
• a processing device, wherein
• the illumination optical system includes a light source, a condenser lens, and an aperture member,
• the observation optical system includes an objective lens and an imaging lens,
• the holding member is configured to hold a sample and is disposed between the illumination optical system and the observation optical system,
• the drive device changes a distance between the holding member and the observation optical system,
• the light-receiving device is disposed at a position where light emitted from the observation optical system is received,
• the processing device comprises
• a unit configured to obtain a quantity of light from a predetermined region of the received light,
• a unit configured to calculate a difference or a ratio between the quantity of light in the predetermined region and a quantity of light as a reference,
• a unit configured to compare a result of the calculation with a threshold, and
• a unit configured to control a change in the distance,
• the aperture member has a light-shielding part or a darkening part, and a transmission part,
• at least part of the transmission part is located outside the light-shielding part or the darkening part,
• the predetermined region is a partial region of the sample,
• when the calculation result is equal to or smaller than the threshold, processing in the processing device is terminated,
• the focusing device further comprises a unit configured to detect the predetermined region and a unit configured to store the predetermined region,
• the unit configured to detect includes
• a unit configured to record the distance and a quantity of light at the distance, for each of the regions,
• a unit configured to obtain a range in which the quantity of light changes monotonously, for each of the regions, and
• a unit configured to specify a region in which the range is longest among the regions.