Displacement amount measuring device, displacement amount measuring method, and recording medium

A non-transitory recording medium that stores a program for causing a computer to execute processing, the processing comprising:

• by using a device including an image capturing element that captures an image of a surface of a specimen and optical path length converting material being disposed between the specimen and the image capturing element in such a way as to cover a part of a field of view of the image capturing element,
• calculating a first displacement amount in the surface of the specimen obtained in a field of view of the image capturing element that is not covered by the optical path length converting material and a second displacement amount in the surface of the specimen obtained in a field of view of the image capturing element covered by the optical path length converting material, by using the image captured by the image capturing element;
• and
• calculating a distance from the specimen to the image capturing element and an out-of-plane displacement of the specimen based on the first displacement amount and the second displacement amount.