Optical system for measuring optical characteristics and device for measuring optical characteristics

An optical system for measuring optical characteristics for measuring reflected light from a measurement target, the optical system for measuring optical characteristics comprising:

• a first optical system and a second optical system that measure a common measurement target,
• the first optical system including, in order from an object side:
• a first lens group having positive power;
• a second lens group having positive power;
• and
• a first imaging element,
• the first optical system having an illumination light source,
• the first optical system being a relay optical system that forms an intermediate image between the first lens group and the second lens group,
• the first imaging element being arranged conjugate with object side infinity, and
• the second optical system including, in order from the object side,
• the first lens group shared by the first optical system;
• an aperture stop;
• a third lens group having positive power;
• and
• a second imaging element,
• the second imaging element being arranged at a position conjugate with the measurement target, wherein
• when a distance in an optical axis direction from an image side paraxial focal point of the first lens group to the aperture stop is represented by Δp and a focal distance of the first lens group is represented by f1, following conditional expression (1) is satisfied
• −1.0<Δp/f1<3.0 (1),
• the first optical system and the second optical system share the first lens group,
• the optical system for measuring optical characteristics further includes an optical element that deflects an optical axis to an image side of the first lens group, and the optical axis is branched into two directions by the optical element,
• the first optical system is arranged in a first direction of the two directions, and
• the second optical system is arranged in a second direction of the two directions.