Correction method, correction apparatus, and inspection apparatus

A correction apparatus comprising:

• an illumination optical system configured to illuminate an object to be inspected by using critical illumination by illumination light generated by a light source;
• a detection optical system configured to concentrate light from the object to be inspected illuminated by the illumination light and acquire image data of the object to be inspected by detecting the concentrated light by a first detector;
• a monitor unit configured to acquire image data of a brightness distribution of the illumination light detected by irradiating a second detector with critical illumination by using part of the illumination light;
• and
• a processing unit configured to correct the image data of the object to be inspected based on the image data of the brightness distribution;
• wherein a magnification of the image data of the brightness distribution acquired by the monitor unit is lower than a magnification of the image data of the object to be inspected acquired by the detection optical system;
• wherein the processing unit interpolates data between each pixel included in the image data of the brightness distribution and thereby conforms a resolution of the image data of the brightness distribution to a resolution of the image data of the object to be inspected.