Measurement apparatus and method of operating measurement apparatus

1. A measurement apparatus comprising:

an observation optical system including a first pupil and a second pupil, the first pupil being capable of transmitting first light of a first wavelength band, and the second pupil being capable of transmitting second light of a second wavelength band different from the first wavelength band;

an imaging device disposed at a position at which light transmitted through the observation optical system is incident and including a plurality of first pixels and a plurality of second pixels, the plurality of first pixels configured to generate first pixel signals based on third light of a third wavelength band transmitted through a first optical filter that is capable of transmitting the third light, the plurality of second pixels configured to generate second pixel signals based on fourth light of a fourth wavelength band transmitted through a second optical filter that is capable of transmitting the fourth light, and the fourth wavelength band being different from the third wavelength band;

a light source configured to output illumination light including only fifth light of a fifth wavelength band and sixth light of a sixth wavelength band not overlapping the fifth wavelength band; and

a controller comprising hardware, the controller being configured to:

acquire a first image based on the first pixel signals and a second image based on the second pixel signals from a captured image based on the first pixel signals and the second pixel signals; and

measure a phase difference between the first image and the second image,

wherein the observation optical system comprises a monocular optical system and includes a pupil filter, and

the pupil filter includes:

a transparent flat plate;

a thin film, in which a first opening portion and a second opening portion are formed, disposed on a surface of the flat plate;

the first pupil comprising a third optical filter disposed at the first opening portion and configured to transmit the first light; and

the second pupil comprising a fourth optical filter disposed at the second opening portion and configured to transmit the second light,

at least a part of the first wavelength band and at least a part of the third wavelength band overlap each other,

at least a part of the first wavelength band and at least a part of the fifth wavelength band overlap each other,

at least a part of the fifth wavelength band and at least a part of the third wavelength band overlap each other,

the first wavelength band and the sixth wavelength band do not overlap each other,

at least a part of the second wavelength band and at least a part of the fourth wavelength band overlap each other,

at least a part of the second wavelength band and at least a part of the sixth wavelength band overlap each other,

at least a part of the sixth wavelength band and at least a part of the fourth wavelength band overlap each other, and

the second wavelength band and the fifth wavelength band do not overlap each other.

2. The measurement apparatus according to claim 1 , wherein:

the controller is further configured to set a state of the light source to one of a first state and a second state,

the light source is configured to output first illumination light including only the fifth light and the sixth light when the first state is set in the light source,

the light source is configured to output second illumination light including only one of the fifth light and the sixth light when the second state is set in the light source, and

only one of the first image and the second image is output to a display when the second state is set in the light source.

3. The measurement apparatus according to claim 1 , wherein the controller is further configured to control light intensities of the fifth light and the sixth light on the basis of a degree of difference in brightness between the first image and the second image.

4. The measurement apparatus according to claim 1 ,

wherein the light source includes:

one or more first light emitting devices configured to generate the fifth light; and

one or more second light emitting devices configured to generate the sixth light.

5. The measurement apparatus according to claim 4 , further comprising:

an illumination optical system configured to emit the illumination light supplied from the light source to a subject,

wherein the light source further includes an optical mixing unit configured to mix the fifth light supplied from the first light emitting device and the sixth light supplied from the second light emitting device and output the illumination light including the fifth light and the sixth light that are mixed.

6. The measurement apparatus according to claim 5 , further comprising:

an insertion part to be inserted into the subject,

wherein the illumination optical system includes a light guide configured to transfer the illumination light supplied from the optical mixing unit to a tip end of the insertion part.

7. The measurement apparatus according to claim 1 , further comprising:

an illumination optical system configured to emit the illumination light supplied from the light source to a subject,

wherein the illumination optical system includes an optical mixing unit configured to mix the fifth light supplied from the light source and the sixth light supplied from the light source.

8. The measurement apparatus according to claim 7 , further comprising:

an insertion part to be inserted into the subject,

wherein the illumination optical system further includes a light guide configured to transfer the illumination light supplied from the optical mixing unit to a tip end of the insertion part.