Fiber Digital Holography And Its Applications

Fiber digital holography is a useful technology which applies fiber to digital holography. It makes all kinds of complicated optical apparatus dispensable, and makes the experimental set-up more concise and compact. This technology expands the application fields of digital holography. This paper proves the feasibility of applying fiber to digital holography. The main contents are:(1) The recording and numerical reconstruction of lensless Fourier hologram are analyzed by spherical wave theory. Light from a He-Ne laser is divided in two beams, each launches through different fibers. One fiber carries the object beam illumination and the other conveys the reference beam towards the detector of a CCD camera. The lensless Fourier holograms of transparent and opaque objects are thus obtained. The MATLAB program is used to reconstruct the image of objects and by several ways of digital image-processing such as band-pass filtering and V-filtering, the quality of reconstruction image is greatly improved. The unfocused hologram of lensless Fourier holography are also discussed, and a way to revise the reconstruction image of unfocused hologram is presented .(2) The reconstruction of image plane hologram is analyzed by plane wave theory. The image plane holograms of transparent and opaque objects are also obtained by using fibers. The clear images of objects are reconstructed by using frequency domain algorithm.(3) In experiment, different reconstruction images are obtained by using different fibers. Laser beam can be coupled to Y-fiber, plastic fiber and glass fiber which with big diameters (l-2mm) much easier than quasi monomode fiber whose diameter is only several microns. The former fibers can transmit much more beam illumination, but their light fields are not as even as the quasi monomode fiber's. Several other questions of fiber digital holography are also discussed briefly.(4) The fundamental principles of fiber digital holographic interferometry is presented. Based on this, the Poisson's ratio of material, the deformation of a metal plate and the temperature distributing arounding a electric iron are successfully measured. The lensless Fourier hologram of object by using selfoc lens is obtained, and the clear image is numerical reconstructed.