Image pickup apparatus, measuring apparatus, and article manufacturing method

An image pickup apparatus comprising:

• an image sensor;
• and
• an optical system includes a dispersion element and a diffractive element,
• wherein the dispersion element is configured to divide light from an area extending in a first direction of an object into a plurality of lights in a section orthogonal to the first direction,
• wherein the diffractive element is configured to condense the plurality of lights on an imaging surface of the image sensor,
• wherein a base surface of a diffractive surface of the diffractive element is asymmetric in the first direction, and
• wherein the following inequalities are satisfied:
• 0.90≤α21/α32≤1.10
• 1×10-12≤|α21|≤1×10-6
• where λ1, λ2, and λ3 are wavelengths of first light, second light, and third light among the plurality of lights, respectively, satisfying the following inequality, z1, z2, and z3 are condensed positions of the first, second, and third lights on the imaging surface in the section, respectively, and α21 and α32 are defined as follows:
• λ1<λ2<λ3
• α21=(z2−z1)/(1/λ2−1/λ1)
• α32=(z3−z2)/(1/λ3−1/λ2).