VARIATION OF DENSITY WITH NUMERICAL APERTURE

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A000200010040-5
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 17
• Document Creation Date: December 28, 2016
• Document Release Date: March 22, 2001
• Sequence Number: 40
• Publication Date: July 31, 1964
• Content Type: MEMO

roved For Release.2001/04/02 : CIA-RDP78BO4747A000200010040-5
31 July 1964
HH: bb: 3 62
(997-112)
MEMORANDUM
STATINTL
STATINTL To:
From
Subject: Variation of Density with Numerical Aperture
CC:
INTRODUC TION
aperture. The prime reason for density difference with numerical aperture is
the scattering of light by the grainy emulsione
uar numerical aperture when the density was known for a different numerical
STATINTL
This memorandum presents the results of a study to determine the
dependence of photographic density of various films on parameters such as numer-
ical aperture, film gamma, development time, granularity and exposure. Ex-
plicitely the objective was to provide the rules for predicting density, for a partic-
This memo contains three sections. The first describes the experi-
The sample films included in the scanning were chosen on the basis of availability.
angle of the cone pf light collected from each point on the sample b the dqetect L
y de ector
of the sample, and the numerical aperture of the detector is the sine of the half-
the source is the sine of the half-angle of the cone of light illuminating each point
of numerical apertures of the source and detector. The numerical aperture of
wedge (on the sample film) with a microdegsitomet r using several combinations
The general procedure for obtaining den-city values is to scan a etep
EXPERIMENTAL ?ROCEDURE
recommendations for a procedure for density value prediction..'
presents the results in terms of Callier's c~ factor, and the third contains
mental procedure for measuring density values of various samples, the second
N I
These films provide a large range in granularity
Which is a parameter strongly related to scattering. The sampleswere produced
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 Approved For Release 2001/04/02 : dfA-RDP78B04747A000200010040-5
STATINTL
STATINTL
STATINTL
STATINTL
STATINTL
by-iiagiriga_ step wedge onto the samples With an enlarger. A reduction
in image size was provided such that all densities in the wedge could be mea-
sured from a single scan by the _Model 4 microdonsitometer. In addition
to the size reduction, the image was slightly defocused to assure that density
fluctuation in the steps of the_ wedge were not reproduced on the sample.
The amount of defocus was assumed sufficient when edge blurring was in evi-
dence to the eye since the fluctuations were not visible even when in focus. The
defocus was not enough to smear the steps together however. The processing
of the sample films conformed to normal practice.* Table (1) lists the samples
generated along with their nominal granularity values and processing. In one
case the processing was varied by including development time, both
long and short compared to tLe normal 5 minutes. These are marked by * in
Table (1).
Film Type
Developer Development Time
0.085 D-19 3 min.
0.020 DK-50 5
0.014 D-19 5