Hopkins suggests specific short-cuts in testing in accor- 
dance with application. He also emphasizes the need for computer 
tie-in which directly acquires, reduces, and analyzes data. 
Without the computer, the old reliable eyeball method of examining 
an infinite point source will be quicker and more informative 
for the optical designer and the shop technician. 
The major importance of OTF testing is that the distri- 
bution of light in the images may be both calculated and measured, 
making quality comparison between predictions and results possible. 
The lenses, however, need to be tested in ways similar to the 
methods used in lens designs so that the designers can receive 
accurate information on the consequences of their assigned tolerances. 
The use of various short-cuts, with computers directly connected 
with the optical bench and evaluation by an agreed FOM will 
then make OTF testing feasible and optically informative. 
5.9.7 Itek Corporation 
5.9.7.1 Use of MIF/4,75 
Itek employs various image analysis techniques in both 
design and testing of optical systems. In specific computerized 
calculations of the lens, MTF permits the prediction of image 
quality for the most general cases of field angle, target orienta- 
tion, spectral response, and detector characterisitics. Computer 
programs are thus used to determine the performance of both photo- 
graphic and electro-optical systems at various stages from design 
to operational. 
In the design phase the lens MTF or lens modulation 
at particular spatial frequencies, are often specified as the 
design criteria. The complexity of the lens form and the degree 
of design optimization is thus driven by MIF requirements. In 
the design optimization, the monochromatic and polychromatic 
aberrations are balanced across the fíeld of view depending upon 
their effect on the MIF. 
In the static hardware phase the fabrication, assembly, 
and test specifications are also often specified as an allowable 
degradation of the nominal lens MIF. For these lenses, an error 
budget is generated based on a calculated change in MTF for each 
parameter in the lens to be toleranced. The more common practice 
is to correlate the MTF degradation to a wavefront error, since 
it is a more easily measured quantity, and generate a wavefront 
error budget. Verification that a lens system has achieved the 
specified MTF is accomplished by measuring the wavefront errors 
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