Optical method and arrangement for measuring residual stresses, in particular in coated objects

A device for determining residual stresses of an object, the device comprising:

• a laser exposure system comprising:
• at least a first laser;
• and
• an optical scanning device to apply laser light to a surface of the object and to generate a pattern of holes or a pattern of locally heated points in the object, wherein the optical scanning device comprises:
• an optical deflection and/or modulation arrangement to controllably modulate the laser light;
• or
• a focusing arrangement to controllably focus the laser light;
• and
• an optical measuring system that determines a deformation of the surface of the object, wherein the optical scanning device is further programmed and adapted to:
• adapt a shape of the pattern of holes or of the pattern of locally heated points to at least one of a topography of the surface of the object, one or more residual stresses in the object, or a gradient of the one or more residual stresses in the object;
• or
• adapt a position of the pattern of holes or of the locally heated points to at least one of a topography of the surface of the object, the determined one or more residual stresses, or a gradient of the one or more residual stresses in the object.

A method for determining residual stresses of an object comprising:

• applying, by a laser exposure system, laser light to a surface of the object;
• creating a pattern of holes or a pattern of locally heated points in the object;
• after applying the laser light to the object, using an optical deformation measurement to determine one or more surface deformations;
• determining, based on the one or more surface deformations, one or more residual stresses in the object;
• and
• adapting a position of the pattern of holes or of the locally heated points to at least one of a topography of the surface of the object, the determined one or more residual stresses, or a gradient of the one or more residual stresses in the object.