Adjustment device and operation method of adjustment device

An operation method of an adjustment device, the adjustment device including:

• a mask holding portion configured to hold a mask of an imaging device and adjust a position and an angle of the mask relative to an imaging element, the mask including a transmissive region including a plurality of fresnel zone plates (FZPs) and a plurality of light-shielding regions and being configured to modulate incident light into modulated light by causing the incident light to pass through the mask, the imaging element being configured to capture a modulated image including the modulated light passing through the mask, the imaging device including the mask, the imaging element, and a reconstruction unit configured to reconstruct an image corresponding to the incident light on a basis of the modulated image;
• and a point light source configured to emit white light as the incident light,
• the operation method comprising controlling the mask holding portion to adjust the mask to establish a predetermined positional relationship between the mask and the imaging element on a basis of a color of light corresponding to a wavelength of an image captured by the imaging element when the white light passes through the mask as the incident light.