Observation device and observation method

An observation apparatus comprising:

• a light source configured to output light;
• an irradiation optical system including a mirror in which an orientation of a reflection surface is changeable, and configured to irradiate an observation object with the light from each of a plurality of light irradiation directions according to the orientation of the reflection surface of the mirror;
• an imager configured to image an interference intensity image at a reference position generated by interference between the light irradiating the observation object along each of the plurality of light irradiation directions and passed through the observation object and reference light;
• an imaging optical system including an objective lens and an imaging lens, and configured to set an image plane position having a conjugate relationship with respect to an imaging plane of the imager as the reference position for the observation object;
• and
• at least one processor configured to perform processes of:
• an interference intensity image acquisition unit configured to acquire, for each of the plurality of light irradiation directions, the interference intensity image at the reference position from the imager;
• a first complex amplitude image generation unit configured to generate a complex amplitude image at the reference position based on the interference intensity image at the reference position for each of the plurality of light irradiation directions;
• and
• a two-dimensional phase image generation unit configured to generate a two-dimensional phase image based on the complex amplitude image of each of the plurality of light irradiation directions, wherein
• the two-dimensional phase image generation unit is configured to:
• generate a complex differential interference image of each of the plurality of light irradiation directions based on the complex amplitude image of each of the plurality of light irradiation directions, and
• generate the two-dimensional phase image based on a summation of the complex differential interference images of the plurality of light irradiation directions.