Imaging device, substrate observation apparatus, substrate processing apparatus, and imaging method

An imaging device for imaging a peripheral edge part of a substrate being rotated, comprising:

• an imager configured to periodically perform imaging;
• an optical guider configured to guide light emitted from the peripheral edge part to the imager so as to form a first figure of the peripheral edge part viewed from a first direction and a second figure of the peripheral edge part viewed from a second direction different from the first direction in an imaging field of view of the imager;
• and
• an arithmetic processor configured to perform image processing on each of a first image including the first figure and a second image including the second figure, the first image and the second image being captured by the imager,
• wherein the imager cyclically switches a plurality of imaging conditions for each imaging, the imaging conditions including a first condition corresponding to imaging of the first figure and a second condition corresponding to imaging of the second figure, and
• the arithmetic processor acquires the first image from an image captured by the imager under the first condition and acquires the second image from an image captured by the imager under the second condition.