Types of holograms may be classified as Fraunhofer, side-bank Fresnel, 
Fourier-Transform, and Fresnel. 
To date, holograms have be* n formed utilizing a number of techniques 
and processes including the use of very intense coherent quasi-monochromatic 
beams of light; incoherent quasi-monochromatic radiation; quasi-monochro 
matic partially coherent radiation; optical spatial filtering; X-band radiation 
(constructed with visible radiati on); and laser beams having more than one 
spectral component. 
The impacts of the laser and holography technologies on that of photo- 
grammetry and allied disciplines are potentially great. Since the applications 
of lasers and holography are expanding so rapidly, it is impossible to do justice 
to many of them in this paper. One possible use would be to make a contour map 
of some object through the use of light at two slightly different frequencies. The 
resulting hologram would contain a series of fringes that represent contours of 
constant distance from the recording plane. Another possible use would be the 
preparation of thick-emulsion holograms in full color through the utilization of 
coherent light in the three primary colors; reconstruction of the image would 
be accomplished by illuminating the hologram with the same three primary colors 
(in other words, a color image is formed from a black-and-white emulsion). It 
is to be noted that lasers generate radiant energy in areas of the spectrum other 
than the red and infrared. 
Other areas of application include microscopy (two-step holographic 
processing), optical data processing, computing, data storage and holographic 
interferometry. It should be noted, however, that holograms of moving objects 
cannot be formed as stationary interference fringes cannot b_ obtained under 
such conditions. 
DIGITAL EQUIPMENT ALLIED WITH PhOTOGRAMMETRIC EQUIPMENT. 
The photogrammetric community first felt the impact of data processing 
equipment more than twenty years ago. F rom those early days of digital lens 
computations to the present we have seen an ever increasing emphasis on the 
use of such equipment in photogrammetric mapping operations. The future 
should see an even greater emphasis on their use as well as an emphasis on 
efficient application programming of these computer-aided operations. Included 
in this category are operations pertaining to projection and scale transformations, 
line vectorizing, compaction, correlation, ortho-correction, symbol and line 
generation, curve smoothing, and digital photogrammetric data adjustment-- 
just to name a few. 
A number of current major problems come to mind regarding the use of 
digital equipment in connection with photogrammetric operations. Apparently, 
it is still difficult to determine when to use general-purpose equipment with its 
improving economics and flexibility; when to use special-purpose equipment 
performing one or two major operations in the total photogrammetric mapping 
process; when to use small computers off-line or on-line in connection with 
large general-purpose computers; and when to use small computers in a