Optical EngineeringElectronic speckle pattern shearing interferometer using holographic gratings
|Format||Member Price||Non-Member Price|
|GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free.||Check Access|
We propose two methods to perform shearing in electronic speckle pattern shearing interferometry (ESPSI). These new methods of shearing make the setup compact and easy to align. The first system we propose consists of two parts: (1) the object is imaged onto an intermediate ground glass and (2) the image on the ground glass is in turn imaged onto the photosensor of a CCD camera. A holographic grating placed in front of the ground glass screen is used to shear the two images and to introduce phase stepping. The separation between the grating and the ground glass plate is used to control shearing. In the second method, two identical holographic gratings separated by a distance introduce shearing and the distance between two gratings can be used to control the size of shearing. Phase shifts to be employed for phase measurements are introduced by displacing the grating.