Optical element assembly, optical apparatus, estimation method, and non-transitory storage medium storing estimation program

An optical apparatus comprising:

• an optical element assembly including:
• a wavelength selection portion comprising a plurality of wavelength selection regions, the wavelength selection portion being configured to emit wavelengths in a predetermined range, the wavelengths being different among the plurality of wavelength selection regions;
• and
• an imaging optical element comprising a plurality of different regions,
• the plurality of regions of the imaging optical element having focal lengths different from each other, and
• each of the regions of the imaging optical element optically faces corresponding one of the wavelength selection regions of the wavelength selection portion;
• an image sensor configured to capture light emitted from the optical element assembly,
• the image sensor including at least two different pixels, and
• each of the pixels having at least two color channels;
• and
• an image processor connected to the image sensor, the image processor including a processor configured to:
• acquire images of the at least two color channels by the image sensor,
• calculate a contrast of a common region of an object for each of the images of the at least two color channels, wherein the contrast is based on spatial gradients or the contrast is based on each of the images;
• and
• estimate, based on the contrast of the common region for each of the at least two color channels, a farness/nearness and/or a distance of the object with respect one of the imaging optical element and the image sensor.