Abstract

An inverse densitometric circuit is described which employs the technique of voltage-transfer curve translation to provide a direct linear measure to photographic-energy profiles. An antilog D scale (reciprocal-transmittance scale) linear to ±0.05 antilog D units over a basic antilog D range of 12 is obtained. Neutral-density filters are used to compound the basic sensitivity increment and obtain a total light-level range in excess of 1 to 103. An optical system is described which provides an instrument resolving power of 500 lines/mm.

© 1961 Optical Society of America

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References

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  1. P. Hariharan and M. S. Bhalla, Rev. Sci. Instr. 27, 3 (1956).
    [Crossref]
  2. R. W. Engstrom, J. Opt. Soc. Am. 37, 420 (1947).
    [Crossref]
  3. M. Banning, J. Opt. Soc. Am. 37, 686 (1947).
    [Crossref]
  4. K. Frei and Hs. H. Gunthard, J. Opt. Soc. Am. 51, 83 (1961).
    [Crossref] [PubMed]

1961 (1)

1956 (1)

P. Hariharan and M. S. Bhalla, Rev. Sci. Instr. 27, 3 (1956).
[Crossref]

1947 (2)

Banning, M.

Bhalla, M. S.

P. Hariharan and M. S. Bhalla, Rev. Sci. Instr. 27, 3 (1956).
[Crossref]

Engstrom, R. W.

Frei, K.

Gunthard, Hs. H.

Hariharan, P.

P. Hariharan and M. S. Bhalla, Rev. Sci. Instr. 27, 3 (1956).
[Crossref]

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Figures (5)

Fig. 1
Fig. 1

Machine-calculated behavior of the reciprocal response function for a predominantly parabolic voltage transfer curve.

Fig. 2
Fig. 2

Diagram of the dual detecting-recording circuit. Wire-wound resistances and matched precision components were used when practicable.

Fig. 3
Fig. 3

Diagram of optical system.

Fig. 4
Fig. 4

Empirical plot of instrumental reciprocal response function using calibrated photographic transmission step tablet.

Fig. 5
Fig. 5

Calibration curve of circuit.

Equations (12)

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v s = a + b F d + c F d 2 + d F d 3 + .
f ( v s v r ) = a + b F d + c F d 2 + d F d 3 + v r .
f d ( v s v r ) = v s + v a v r + v a = ( v a - v c ) + b F d + c F d 2 + d F d 3 + v r + v a ,
0 ( v s + v a ) ( v r + v a )
f d ( v s v r ) = δ + b F d + c F d 2 β ,
0 ( v s + v a ) ( v r + v a ) δ = ( v a - v c ) ;             β = ( v r + v a ) .
f s ( v r v s ) = [ f d ( v s v r ) ] - 1 = β x 2 δ x 2 + b x + c ,
( v r + v a ) ( v s + v a ) v m ;             1 x x m ;
f s ( v r v s ) = 2 β c 2 - δ b x 3 - 3 δ c x 2 ( δ x 2 + b x + c ) 3
b x 3 + 3 c x 2 - c 2 δ = 0
δ x 2 + b x + c = 0.
f s ( v r / v s ) F s + γ