Speckle Interferometry Made Simple and Cheap

Unifying Concepts in Teaching Optical Methods

“…Experiments to demonstrate simple subtraction electronic speckle interferometry are simple and inexpensive to set up and run. 4 As these ideas are developed, the limitation of interferometries in determining absolute path length changes will be obvious. Phase stepping can be introduced as a method to obtain absolute path length changes; it can be introduced as an extension of the compensation techniques studied with photoelasticity.…”

3D digital image correlation methods for full-field vibration measurement

“…Common ways to obtain vibration measurements include using a wide array of accelerometers and the properties of a monochromatic light source such as a laser. The latter method includes numerous techniques including a scanning laser vibrometer, digital speckle shearography, (DSI), electronic speckle pattern interferometry (ESPI), and holographic interferometry [6][7][8][9]. Full-field measurement of vibrating structures is typically conducted by either attaching an array of numerous sensors to the structure or by performing roving accelerometer (or modal hammer) measurements.…”