Abstract

We will describe a lensless imaging system which utilizes the advantages of electronic processing to produce high quality images. The principle behind the lensless imaging system is based on the mutual coherence function. When spatially broad, spectrally coherent light is used in an interferometer, interference will only occur at those point in the hologram plane where the object and reference beam’s coherence functions match. If the object is placed the prober distance from the hologram plane, a point to point mapping of the object to the hologram can be made. Thus the object is “imaged” to the hologram plane. The use of electronic holography affords many advantages over more conventional methods, including the ability to accumulate images both coherently and incoherently resulting in an increased signal-to-noise ratio. The limited spatial resolution of a CCD camera causes a degradation in image resolution when a spatial carrier is used to record the hologram. This problem can be overcome by introducing a temporal carrier. By changing the phase of the reference beam, object information can be extracted from the varying intensity patterns on the hologram plane. This technology will be applicable to areas ranging from metrology to imaging through inhomogeneities.

© 1993 Optical Society of America