A system and a method for measuring the focus state of an optical instrument are described. The system and the method provide for forming an image of the exit pupil of the objective of the optical instrument. Where the image of the exit pupil is formed, one or more optical elements are placed, deviating at least part of the rays coming from the exit pupil, so that rays coming from different non-overlapping portions of the pupil follow separate optical paths. The rays coming from the two portions of the pupil are then focused, in order to obtain two bidimensional images. A computer determines the mutual distance between these two bidimensional images as a mutual rigid lateral displacement between the two and, based on this distance, determines the corresponding defocus of the optical instrument.

An imaging device includes a multifocal main lens having different focal distances for a plurality of regions, an image sensor having a plurality of pixels configured of two-dimensionally arranged photoelectric converting elements, a multifocal lens array having a plurality of microlens groups at different focal distances disposed on an incident plane side of the image sensor, and an image obtaining device which obtains from the image sensor, a plurality of images for each of the focal distances obtained by combining the multifocal main lens and the plurality of microlens groups at different focal distances.

The present disclosure relates to a low-light autofocus technique. One example embodiment includes a method. The method includes receiving an indication of a low-light condition for a camera system. The method also includes determining an extended exposure time for a low-light autofocus procedure of the camera system. Further, the method includes capturing, by the camera system, an extended frame for the low-light autofocus procedure. The extended frame is captured by die camera system using the determined extended exposure time. In addition, the method includes determining, based on the captured extended frame, an in-focus lens setting for a lens of the camera system.

An image acquisition device includes: a stage on which a sample is placed; a drive unit; a first irradiation optical system; a second irradiation optical system; a beam splitter; a pupil dividing element; a first imaging lens; a first imaging element; an analysis unit; a control unit; a second imaging lens; and a second imaging element, a first irradiation light irradiation range captured by the first irradiation optical system includes a second imaging region captured by the second imaging element, the second imaging region is located behind a first imaging region in a scanning direction, and the control unit controls a focus position of an objective lens based on focus information before capturing the second imaging region by the second imaging element.

A system and a method for measuring the focus state of an optical instrument are described. The system and the method provide for forming an image of the exit pupil of the objective of the optical instrument. Where the image of the exit pupil is formed, one or more optical elements are placed, deviating at least part of the rays coming from the exit pupil, so that rays coming from different non-overlapping portions of the pupil follow separate optical paths. The rays coming from the two portions of the pupil are then focused, in order to obtain two bidimensional images. A computer determines the mutual distance between these two bidimensional images as a mutual rigid lateral displacement between the two and, based on this distance, determines the corresponding defocus of the optical instrument.

In the image capturing apparatus, the optical path difference producing member is disposed on the second optical path. Thereby, the amount of light for imaging an optical image which is focused at the front of an optical image made incident into the first imaging device (front focus) and an optical image which is focused at the rear thereof (rear focus) by the second imaging device can be suppressed to secure the amount of light on image pickup by the first imaging device. Further, in the image capturing apparatus, at least one of a position of the first imaging region and a position of the second imaging region on the imaging area is changed, thus making it possible to easily adjust an interval between the front focus and the rear focus. It is, thereby, possible to detect a focus position of the sample at high accuracy.

An imaging apparatus includes: a focus detection unit that detects a defocus amount using the pair of parallax image signals; a control unit that controls adjustment of a focus position based on the defocus amount; a first determination unit that determines whether a subject with a repetitive pattern is being imaged in a focus detection area; and a second determination unit that determines whether a degree of image blurring is equal to or more than a predetermined degree of blurring. When the first determination unit determines that a subject with a repetitive pattern is being imaged and the second determination unit determines that a degree of image blurring is equal to or more than the predetermined degree of blurring, the control unit moves a focus lens to acquire a new defocus amount.

An imaging apparatus includes: a focus detection unit that detects a defocus amount using the pair of parallax image signals; a control unit that controls adjustment of a focus position based on the defocus amount; a first determination unit that determines whether a subject with a repetitive pattern is being imaged in a focus detection area; and a second determination unit that determines whether a degree of image blurring is equal to or more than a predetermined degree of blurring. When the first determination unit determines that a subject with a repetitive pattern is being imaged and the second determination unit determines that a degree of image blurring is equal to or more than the predetermined degree of blurring, the control unit moves a focus lens to acquire a new defocus amount.

In the image capturing apparatus, the optical path difference producing member is disposed on the second optical path. Thereby, the amount of light on imaging an optical image which is focused at the front of an optical image made incident into the first imaging device (front focus) and an optical image which is focused at the rear thereof (rear focus) by the second imaging device can be suppressed to secure the amount of light on image pickup by the first imaging device. Further, in the image capturing apparatus, the first imaging region and the second imaging region on the imaging area of the second imaging device are positioned on the front side of the imaging area in a scanning direction of the sample with respect to the region into which an optical image is made incident which is conjugate to the first optical image made incident into the first imaging device. Thereby, it is possible to obtain in advance a deviation direction of a focus position of the objective lens by a simple constitution.

An auto-focus device, for eliminating an uncomfortable feeling when phase difference AF is switched to optical path length difference AF when an arbitrary area is set as a focusing target area, and a method for controlling operation of the same. A desired area is set as the focusing target area. Until a first threshold value position is reached, the focus lens is moved based on a phase difference AF evaluation value obtained from a phase difference AF sensor so as to bring the center portion of the imaging area into focus. Until a second threshold value position is reached, the focus lens is moved based on a phase difference AF evaluation value which is obtained from a signal of an area corresponding to the set focusing target area. When the focus lens reaches the second threshold value position, the focus lens is positioned at the focusing position.