Methods for measuring strains in circuit substrates such as circuit boards and semiconductor wafers include illuminating a specimen with a substantially collimated laser flux. A temperature change is produced in the specimen and a series of laser speckle patterns produced by a laser flux scattered or reflected by the specimen is recorded. Localized strains are detected based on speckle pattern shifts that are calculated using the recorded speckle patterns. Stains can be recorded as a function of temperature or rate of change of temperature, and strains at one or more circuit substrate locations can be detected.