the hologram should be sampled at each pixel, as in the A-K, to reduce

or eliminate false images.

 Chapter III also describes the SBP required of the CGH to perform

 the optical correlation. The SBP drives the size, complexity and

 expense of the CGH. When used as a matched filter, the requirements

 are more stringent than when used for reconstruction holography.

 However, when the techniques presented at the end of the chapter are

 incorporated, the SBP requirements can be minimized.

 Chapter IV describes preprocessing techniques useful in optimizing

 the CGH matched filter. The high-frequency emphasis and phase-only

 filtering increase the discrimination against false targets but

 sensitize the filter to scale and rotation. The phase-only filter,

 although easy to implement, is not unique in its ability to improve

 signal-to-noise and efficiency. Rather, it is a form of high

 .frequency emphasis which may or may not be optimum. It does minimize

 the dynamic range but may not be the appropriate choice for a specific

 application. The rules describing the application of high frequency

 emphasis should be applied to each case. The exception is when an on-

 axis hologram is to be phase modulated so as to require the reference

 to contain no amplitude information.

 The phase-modulation process applied to the physical hologram

should not be confused with the phase-only filtering step which is

applied to the reference information. That is, a phase-modulated

hologram can utilize the normal reference information, frequency

emphasis or phase-only filtering. In general, the phase modulation

provides considerably higher efficiency with an accompanying loss of

signal-to-noise ratio due to the non-linearity. When using binary