Method for measuring thermo-elastic deformations of objects, including providing: • an interferometric metrology instrument configured to carry out optical measurements; and • a thermal chamber, whose internal temperature is controllable and which is fitted with an inspection window closed by a medium that is transparent to light emitted by the interferometric metrology instrument; wherein said interferometric metrology instrument is arranged outside the thermal chamber in front of the inspection window, thereby being operable to carry out optical measurements through said inspection window; the method further including: • arranging an object to be tested inside the thermal chamber; • operating the thermal chamber to expose the object to one or more predefined test temperatures; • operating the interferometric metrology instrument to carry out, through the inspection window, optical measurements of the object exposed to the predefined test temperature or temperatures; • correcting the optical measurements to compensate for propagation through the medium of the light emitted by the interferometric metrology instrument; and • detecting and measuring thermo-elastic deformations of the object based on the corrected optical measurements; the method being characterized by a preliminary calibration step including: • carrying out, by means of the interferometric metrology instrument, calibration measurements of the object, or of a calibration reference template, arranged inside the thermal chamber, wherein the calibration measurements comprise - at least a first calibration measurement of the object, or of the calibration reference template, carried out by the interferometric metrology instrument through the inspection window closed by the medium, and - at least a second calibration measurement of the object, or of the calibration reference template, carried out by the interferometric metrology instrument through the inspection window without the medium; and • determining, based on the calibration measurements, refraction and phase shift compensation laws related to propagation through the medium of the light emitted by the interferometric metrology instrument; wherein the optical measurements are corrected based on the refraction and phase shift compensation laws. • an interferometric metrology instrument configured to carry out optical measurements; and • a thermal chamber, whose internal temperature is controllable and which is fitted with an inspection window closed by a medium that is transparent to light emitted by the interferometric metrology instrument; • arranging an object to be tested inside the thermal chamber; • operating the thermal chamber to expose the object to one or more predefined test temperatures; • operating the interferometric metrology instrument to carry out, through the inspection window, optical measurements of the object exposed to the predefined test temperature or temperatures; • correcting the optical measurements to compensate for propagation through the medium of the light emitted by the interferometric metrology instrument; and • detecting and measuring thermo-elastic deformations of the object based on the corrected optical measurements; • carrying out, by means of the interferometric metrology instrument, calibration measurements of the object, or of a calibration reference template, arranged inside the thermal chamber, wherein the calibration measurements comprise - at least a first calibration measurement of the object, or of the calibration reference template, carried out by the interferometric metrology instrument through the inspection window closed by the medium, and - at least a second calibration measurement of the object, or of the calibration reference template, carried out by the interferometric metrology instrument through the inspection window without the medium; and - at least a first calibration measurement of the object, or of the calibration reference template, carried out by the interferometric metrology instrument through the inspection window closed by the medium, and - at least a second calibration measurement of the object, or of the calibration reference template, carried out by the interferometric metrology instrument through the inspection window without the medium; and • determining, based on the calibration measurements, refraction and phase shift compensation laws related to propagation through the medium of the light emitted by the interferometric metrology instrument;