Abstract: Methods for measuring strains in biological and other samples include illuminating a specimen with substantially collimated laser flux. An electro-acoustic transducer is activated to generate acoustic waves in the specimen, including a surface wave component such as a Rayleigh wave. A series of laser speckle patterns produced by a laser flux scattered or reflected by the specimen is recorded and speckle pattern shifts are calculated based on the recorded speckle patterns. Phase shifts produced by acoustic wave propagation in the specimen are used to identify specimen regions associated with irregularities such as inclusions, cracks, or tissue abnormalities. In some examples, specimens are stretched or otherwise stressed by one or more light fluxes, and specimen elongation is estimated based on a series of associated speckle patterns.

Abstract: 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.