R. Gonsalves and P. Considine, "Spot Shaping and Incoherent Optical Smoothing for Raster Scanned Imagery," Opt. Eng. 15, 64–67 (1976).

W. J. Dallas, "Digital Computation of Image Complex Amplitude from Image- and Diffraction-Intensity: An Alternative to Holography," Optik 41, 45–59 (1975).

A. J. Drenth *et al.*, "The Problem of Phase Retrieval in Light and Electron Microscopy of Strong Objects," Opt. Acta 22, 615–628 (1975).

B. J. Hoenders, "On The solution of the Phase Retrievel Problem," J. Math. Phys. 16, 1719–1725 (1975).

V. P. Schiske, "Ein- und Mehrdeutigkeit der Phasenbestimmung aud Bild und Beugeunsfigur," Optik 40, 261–275 (1974).

R. W. Gerchberg and W. O. Saxton, "A Practical Algorithm for the Determination of Phase from Image and Diffraction Plane Pictures," Optik 35, 237–246 (1972).

R. W. Gerchberg and W. O. Saxton, "Phase Determination from Image and Diffraction Plane Pictures in the Electron Microscope," Optik. 34, 275–283 (1971).

D. Dialetis, "Some Theorems Concerning the Phase Problem of Coherence Theory," J. Math. Phys. 8, 1641–1649 (1967).

H. M. Nussenzveig, "Phase Problem in Coherent Theory," J. Math. Phys. 8, 561–572 (1967).

C. L. Mehta, E. Wolfe, and A. P. Balachadran, "Some Theorems on the Unimodular-Complex Degree of Optical Coherence," J. Math. Phys. 7, 133–138 (1966).

E. L. O'Neill and A. Walther, "The Question of Phase in Image Formation," Opt. Acta 10, 33–40 (1963).

A. Walther, "The Question of Phase Retrieval in Optics,"Opt. Acta 10, 41–49 (1963).

E. Wolf, "Is a Complete Determination of the Energy Spectrum of Light Possible from Measurements of the Degree of Coherence?", Proc. Phys. Soc. Lond. 80, 1269–1272 (1962).

D. A. Huffman, "The Generation of Impulse-Equivalent Pulse Trains," I. R. E. Trans IT 8, S10–S16 (1962).

T. T. Taylor and J. R. Whinnery, "Applications of Potential Theory to the Design of Linear Arrays," J. Appl. Phys. 22, 19–29 (1951).

C. L. Mehta, E. Wolfe, and A. P. Balachadran, "Some Theorems on the Unimodular-Complex Degree of Optical Coherence," J. Math. Phys. 7, 133–138 (1966).

R. Gonsalves and P. Considine, "Spot Shaping and Incoherent Optical Smoothing for Raster Scanned Imagery," Opt. Eng. 15, 64–67 (1976).

W. J. Dallas, "Digital Computation of Image Complex Amplitude from Image- and Diffraction-Intensity: An Alternative to Holography," Optik 41, 45–59 (1975).

D. Dialetis, "Some Theorems Concerning the Phase Problem of Coherence Theory," J. Math. Phys. 8, 1641–1649 (1967).

A. J. Drenth *et al.*, "The Problem of Phase Retrieval in Light and Electron Microscopy of Strong Objects," Opt. Acta 22, 615–628 (1975).

R. W. Gerchberg and W. O. Saxton, "A Practical Algorithm for the Determination of Phase from Image and Diffraction Plane Pictures," Optik 35, 237–246 (1972).

R. W. Gerchberg and W. O. Saxton, "Phase Determination from Image and Diffraction Plane Pictures in the Electron Microscope," Optik. 34, 275–283 (1971).

R. Gonsalves and P. Considine, "Spot Shaping and Incoherent Optical Smoothing for Raster Scanned Imagery," Opt. Eng. 15, 64–67 (1976).

R. Gonsalves *et al.*, "On Optical Holographic Filters," Proc. SPIE 45, 293–297 (1974).

B. J. Hoenders, "On The solution of the Phase Retrievel Problem," J. Math. Phys. 16, 1719–1725 (1975).

D. A. Huffman, "The Generation of Impulse-Equivalent Pulse Trains," I. R. E. Trans IT 8, S10–S16 (1962).

S. L. S. Jacoby *et al.*, Iterative Methods for Nonlinear Optimization Problems (Prentice-Hall, Englewood Cliffs, N. J., 1972).

C. L. Mehta, E. Wolfe, and A. P. Balachadran, "Some Theorems on the Unimodular-Complex Degree of Optical Coherence," J. Math. Phys. 7, 133–138 (1966).

D. L. Misell, "An Examination of an Iterative Method for the Solution of the Phase Problem in Optics and Electron Optics," J. Phys. D 6, 2200–2225 (1973).

H. M. Nussenzveig, "Phase Problem in Coherent Theory," J. Math. Phys. 8, 561–572 (1967).

E. L. O'Neill and A. Walther, "The Question of Phase in Image Formation," Opt. Acta 10, 33–40 (1963).

R. W. Gerchberg and W. O. Saxton, "A Practical Algorithm for the Determination of Phase from Image and Diffraction Plane Pictures," Optik 35, 237–246 (1972).

R. W. Gerchberg and W. O. Saxton, "Phase Determination from Image and Diffraction Plane Pictures in the Electron Microscope," Optik. 34, 275–283 (1971).

V. P. Schiske, "Ein- und Mehrdeutigkeit der Phasenbestimmung aud Bild und Beugeunsfigur," Optik 40, 261–275 (1974).

T. T. Taylor and J. R. Whinnery, "Applications of Potential Theory to the Design of Linear Arrays," J. Appl. Phys. 22, 19–29 (1951).

H. B. Voelcker, "Toward a Unified Theory of Modulation Part I: Phase-Envelope Relationships," Proc. IEEE 54, 340–353. (1966).

E. L. O'Neill and A. Walther, "The Question of Phase in Image Formation," Opt. Acta 10, 33–40 (1963).

A. Walther, "The Question of Phase Retrieval in Optics,"Opt. Acta 10, 41–49 (1963).

T. T. Taylor and J. R. Whinnery, "Applications of Potential Theory to the Design of Linear Arrays," J. Appl. Phys. 22, 19–29 (1951).

E. Wolf, "Is a Complete Determination of the Energy Spectrum of Light Possible from Measurements of the Degree of Coherence?", Proc. Phys. Soc. Lond. 80, 1269–1272 (1962).

C. L. Mehta, E. Wolfe, and A. P. Balachadran, "Some Theorems on the Unimodular-Complex Degree of Optical Coherence," J. Math. Phys. 7, 133–138 (1966).

D. A. Huffman, "The Generation of Impulse-Equivalent Pulse Trains," I. R. E. Trans IT 8, S10–S16 (1962).

T. T. Taylor and J. R. Whinnery, "Applications of Potential Theory to the Design of Linear Arrays," J. Appl. Phys. 22, 19–29 (1951).

B. J. Hoenders, "On The solution of the Phase Retrievel Problem," J. Math. Phys. 16, 1719–1725 (1975).

C. L. Mehta, E. Wolfe, and A. P. Balachadran, "Some Theorems on the Unimodular-Complex Degree of Optical Coherence," J. Math. Phys. 7, 133–138 (1966).

D. Dialetis, "Some Theorems Concerning the Phase Problem of Coherence Theory," J. Math. Phys. 8, 1641–1649 (1967).

H. M. Nussenzveig, "Phase Problem in Coherent Theory," J. Math. Phys. 8, 561–572 (1967).

D. L. Misell, "An Examination of an Iterative Method for the Solution of the Phase Problem in Optics and Electron Optics," J. Phys. D 6, 2200–2225 (1973).

A. J. Drenth *et al.*, "The Problem of Phase Retrieval in Light and Electron Microscopy of Strong Objects," Opt. Acta 22, 615–628 (1975).

E. L. O'Neill and A. Walther, "The Question of Phase in Image Formation," Opt. Acta 10, 33–40 (1963).

A. Walther, "The Question of Phase Retrieval in Optics,"Opt. Acta 10, 41–49 (1963).

R. Gonsalves and P. Considine, "Spot Shaping and Incoherent Optical Smoothing for Raster Scanned Imagery," Opt. Eng. 15, 64–67 (1976).

R. W. Gerchberg and W. O. Saxton, "A Practical Algorithm for the Determination of Phase from Image and Diffraction Plane Pictures," Optik 35, 237–246 (1972).

V. P. Schiske, "Ein- und Mehrdeutigkeit der Phasenbestimmung aud Bild und Beugeunsfigur," Optik 40, 261–275 (1974).

W. J. Dallas, "Digital Computation of Image Complex Amplitude from Image- and Diffraction-Intensity: An Alternative to Holography," Optik 41, 45–59 (1975).

R. W. Gerchberg and W. O. Saxton, "Phase Determination from Image and Diffraction Plane Pictures in the Electron Microscope," Optik. 34, 275–283 (1971).

E. Wolf, "Is a Complete Determination of the Energy Spectrum of Light Possible from Measurements of the Degree of Coherence?", Proc. Phys. Soc. Lond. 80, 1269–1272 (1962).

R. Gonsalves *et al.*, "On Optical Holographic Filters," Proc. SPIE 45, 293–297 (1974).

H. B. Voelcker, "Toward a Unified Theory of Modulation Part I: Phase-Envelope Relationships," Proc. IEEE 54, 340–353. (1966).

S. L. S. Jacoby *et al.*, Iterative Methods for Nonlinear Optimization Problems (Prentice-Hall, Englewood Cliffs, N. J., 1972).

Our earlier discussion centered on extraction of *β*(*x*) in the spatial domain. But we find it more intuitive to present examples where one determines *θ* (γ) in the frequency domain.