We propose a new method for vibration measurement in non-rigid test environment with electronic speckle pattern
interferometry (ESPI). The ESPI is useful for non-contact, real-time analysis of vibration. This method needs rigid test
environment, however. When the interferometer and a vibration surface are on a non-rigid table or their environments
are separated, especially at manufacturing areas, high-amplitude, low-frequency noise fluctuation overwhelms a
vibration signal and the amplitude fringes disappear. We use electronic shutter function of a TV camera and reduce
exposure time of an image sensor. With the time reduction, we may extract an image from many input images, during
whose acquisition time noise fluctuation turns back and its magnitude is so small that the vibration signal goes to be
included in the image. We accumulate the images and increase the contrast of the amplitude fringe map.
We evaluated usefulness of this method with circular saw vibration. The interferometer and the saw are fixed on a rigid
board and the noise fluctuation is electronically superposed on the vibration signal with sine wave. This method is
successful for a fluctuation amplitude of 60μm.
A holographic imaging element (HIE) by use of a transmission-type holographic optical element is evaluated by a numerical simulator. To design HIE and evaluate its imaging characteristics, we fabricate a holographic imaging simulator between one-dimensional arbitrary spaces. In the simulator, two calculation methods that are free space propagation and diffraction at the holographic element are used. The propagated light between the input plane and a transmission-type HIE, or between the HIE and the observation plane is calculated by numerical Fresnel propagation. The diffracted light at the HIE is calculated by Kogelnik's coupled wave theory. By using the simulator, imaging characteristics of a pair of point sources and one- dimensional regions are evaluated.