[ { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5qznw-5mm08", "eprint_id": 100195, "eprint_status": "archive", "datestamp": "2023-08-19 03:12:38", "lastmod": "2024-01-14 22:03:50", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "George-N-A", "name": { "family": "George", "given": "Nick" } } ] }, "title": "Radiation Patterns of the Noise Emission from a Gaseous Discharge", "ispublished": "unpub", "full_text_status": "public", "note": "This research was supported by the U. S. Air Force through the Air Force Office of Scientific Research of the Air Research and Development Command, under Contract No. AF18(600)-1113. \n\nThe author wishes to acknowledge the many helpful discussions with C. H. Papas throughout the course of this work. Valuable consultation was also given by G. J. Stanley on radiometer principles and practices during the design of the equipment for the experiments. \n\nThe author wishes to express his appreciation to G. F. Smith who encouraged this work. This research was supported in part by a fellowship grant from the Hughes Aircraft Company.\n\n
Submitted - TR000403.pdf
", "abstract": "Theoretical and experimental radiation patterns are given in spectral form for the thermal radiation from a cylindrical discharge column which is adjacent to a long thin slot in a metallic plane. A spatial distribution is predicted which exhibits interference minima and maxima when the length of the slot and the wavelength of the emission are the same order of magnitude. The analysis is based on Maxwell's equations and the Leontovich-Rytov distributed-source generalization of Nyquist's noise formula.\n\nFraunhofer pattern measurements are presented in which an argon source is used to excite slots of 7.3\u03c0 and 9.5\u03c0 radians in length. Data are also presented to show the effects of variations in the pressure and the d-c current of the discharge. The pattern measuring apparatus is a Dicke radiometer having the following characteristics: frequency 9200 mc/s, bandwidth to the detector 16 mc/s, modulation frequency 1000 c/s, and residual noise level 0.3 rms\u00b0K.\n\nAn interference phenomenon is predicted by the theory and demonstrated by an experiment, even though the source excitation is spatially distributed and essentially uncorrelated in time and in space. The patterns are not even approximately Lambertian, e.g., a thin slot of 9.5\u03c0 radians exhibits a pattern having nine relative maxima in 180\u00b0 with the maximum emission at 63\u00b0 from the normal.", "date": "2019-12-06", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20191204-174344884", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191204-174344884", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "AF18(600)-1113" }, { "agency": "Hughes Aircraft Company" } ] }, "other_numbering_system": { "items": [ { "id": "TN-59-1101", "name": "AFOSR" } ] }, "local_group": { "items": [ { "id": "Caltech-Antenna-Laboratory" } ] }, "doi": "10.7907/BEXE-6F44", "primary_object": { "basename": "TR000403.pdf", "url": "https://authors.library.caltech.edu/records/5qznw-5mm08/files/TR000403.pdf" }, "resource_type": "monograph", "pub_year": "2019", "author_list": "George, Nick" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/g9hn4-vdt86", "eprint_id": 99228, "eprint_status": "archive", "datestamp": "2023-08-19 03:18:01", "lastmod": "2024-01-14 21:59:39", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } } ] }, "title": "Spatial Distribution of Thermal Radiation at Microwave Frequencies", "ispublished": "unpub", "full_text_status": "public", "note": "Research supported by the U. S. Air Force Office of Scientific Research. \n\nThe author wishes to express his indebtedness to his advisor, Professor C. H. Papas, for his helpful suggestions, his stimulating criticisms, and his encouragement throughout all phases of this investigation. \n\nThe author wishes to acknowledge the following helpful discussions of specific topics. \n\nMr. G. D. Boyd, on gaseous discharge tubes Mr. H. H. Kuehl, on antenna theory Professor R. V. Langmuir, on experimental techniques Professor T. Lauritsen, on thermal radiation Professor H. C. Martel, on noise theory Dr. G. F. Smith, on experimental techniques Dr. G. J. Stanley, on radiometer design Mr. C. H. Wilcox, on noise theory. \n\nThanks are also extended to a colleague, H. Feiveson, who read the manuscript; Miss Benita von Klingspor, who prepared the figures; and Mrs. Ruth Stratton, who typed the text. The author is grateful for the generous financial support afforded him under the Howard Hughes Fellowship Program of the Hughes Aircraft Company.\n\nSubmitted - TR000399.pdf
", "abstract": "Theoretical and experimental radiation patterns are given in spectral form for the thermal radiation from thin slots or heated wires having dimensions of the order of the comparison wavelength. Maxwell's equations and noise theory form the basis of the analyses in which three independent methods are used to predict a spatial distribution which exhibits interference minima and maxima. In the first, the wave equation is solved for a noise-excited transmission line which is suddenly short- and open-circuited at alternate ends. By a study of the trapped noise currents, it is found that the radiation pattern has an interference structure which is smoothed as the loss is increased. Secondly, a formula is derived for the radiation pattern of a heated wire by a computation of its absorption in an isothermal enclosure and by an application of the principle of detailed balancing. Finally, the pattern of a long thin slot is computed directly using the Leontovich-Rytov distributed source generalization of Nyquist's noise formula.\n\nFraunhofer pattern measurements are taken for a thin slot excited by a gaseous discharge at 10,100 \u00b1 200\u00b0K. The pattern measuring apparatus is a Dicke radiometer having the following characteristics: frequency 9200 mc/s, bandwidth to the detector 16 mc/s, modulation frequency 1000 c/s, and residual noise level 0.3 rms\u00b0K.\n\nThe theory and the experiment demonstrate an interference phenomenon even though the source excitation is spatially extended and uncorrelated in time and space. The patterns are not even approximately Lambertian, e.g., a thin slot of 9.5\u03c0 radians length exhibits a pattern having nine relative maxima in 180\u00b0 with the maximum emission at 63\u00b0 from the normal.", "date": "2019-10-11", "date_type": "published", "publisher": "California Institute of Technology", "id_number": "CaltechAUTHORS:20191010-160710398", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191010-160710398", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)" }, { "agency": "Hughes Aircraft Company" } ] }, "other_numbering_system": { "items": [ { "id": "AD 217 179", "name": "ASTIA" } ] }, "local_group": { "items": [ { "id": "Caltech-Antenna-Laboratory" } ] }, "doi": "10.7907/RA1K-D737", "primary_object": { "basename": "TR000399.pdf", "url": "https://authors.library.caltech.edu/records/g9hn4-vdt86/files/TR000399.pdf" }, "resource_type": "monograph", "pub_year": "2019", "author_list": "George, Nicholas" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1rx1v-1hp31", "eprint_id": 106169, "eprint_status": "archive", "datestamp": "2023-08-22 00:51:39", "lastmod": "2023-10-20 23:09:52", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } }, { "id": "Jain-Atul", "name": { "family": "Jain", "given": "Atul" } }, { "id": "Melville-R-D-S-Jr", "name": { "family": "Melville", "given": "R. D. S., Jr." } } ] }, "title": "Experiments on the space and wavelength dependence of speckle", "ispublished": "pub", "full_text_status": "public", "keywords": "Speckle Pattern; Contrast Ratio; Pupil Diameter; Probe Motion; Opal Glass", "note": "\u00a9 1975 Springer Science and Business Media LLC. \n\nReceived 03 February 1975; Accepted 04 March 1975. \n\nResearch supported in part by the Air Force Office of Scientific Research.", "abstract": "A comprehensive series of speckle experiments is described for opal glass diffusers ranging in thickness from 10 to 500 \u03bcm. Wavelength decorrelation measurements are made using a cw dye laser source; and accurate square-law detection is provided by the use of an optic-fiber, photomultiplier combination rather than film. For this diffuser set intensity distribution functions, polarized and unpolarized, are plotted. Second-order correlation functions are presented for different apertures, relating diffuser motion and probe motion. Remote texture determination using contrast ratio and frequency decorrelation is illustrated.", "date": "1975-07", "date_type": "published", "publication": "Applied Physics", "volume": "7", "number": "3", "publisher": "Springer", "pagerange": "157-169", "id_number": "CaltechAUTHORS:20201020-104057925", "issn": "0340-3793", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201020-104057925", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)" } ] }, "doi": "10.1007/bf00936019", "resource_type": "article", "pub_year": "1975", "author_list": "George, Nicholas; Jain, Atul; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/49rwm-yn070", "eprint_id": 5911, "eprint_status": "archive", "datestamp": "2023-08-22 00:45:35", "lastmod": "2023-10-16 19:58:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Livanos-A-C", "name": { "family": "Livanos", "given": "Alexander C." } }, { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } } ] }, "title": "Edge diffraction of a convergent wave", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 Copyright 1975 Optical Society of America \n\nReceived 29 July 1974. \n\nThis research was supported by the Air Force Office of Scientific Research.", "abstract": "Closed-form solutions have been derived for the diffraction patterns at the focal plane of (1) a convergent wave of unit amplitude illuminating a segment of a circular aperture and (2) a convergent wave of Gaussian amplitude diffracted by an infinite edge. Photographs showing the main features of these edge transform patterns are presented together with computer-generated graphs.", "date": "1975-03", "date_type": "published", "publication": "Applied Optics", "volume": "14", "number": "3", "publisher": "Optical Society of America", "pagerange": "608-613", "id_number": "CaltechAUTHORS:LIVao75", "issn": "0003-6935", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:LIVao75", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "primary_object": { "basename": "LIVao75.pdf", "url": "https://authors.library.caltech.edu/records/49rwm-yn070/files/LIVao75.pdf" }, "resource_type": "article", "pub_year": "1975", "author_list": "Livanos, Alexander C. and George, Nicholas" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/rphpe-66t70", "eprint_id": 32802, "eprint_status": "archive", "datestamp": "2023-08-19 08:35:12", "lastmod": "2023-10-18 16:19:45", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "D'Orazio-R-J", "name": { "family": "D'Orazio", "given": "R. J." } }, { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } } ] }, "title": "Matched-Filter Detection of Mode-Locked Laser Signals", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1973 Optical Society of America. Received 24 April 1972; revised 26 March 1973. The authors would like to acknowledge that the research was supported in part by the Air Force Office of Scientific Research and to thank Bell Telephone Laboratories for their doctoral support fellowship\nduring the completion of this study.\n\nPublished - DORao73.pdf
", "abstract": "The passive Fabry-Perot cavity is shown to be a good practical approach to the match-filter optimization for the sensitive detection of mode-locked laser signals. Doppler measurements of relative motion over a wide range of velocities are possible simply by measuring the cavity length for a peak output.", "date": "1973-10", "date_type": "published", "publication": "Applied Optics", "volume": "12", "number": "10", "publisher": "Optical Society of America", "pagerange": "2367-2372", "id_number": "CaltechAUTHORS:20120731-073412293", "issn": "0003-6935", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120731-073412293", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)" }, { "agency": "Bell Telephone Laboratories" } ] }, "doi": "10.1364/AO.12.002367", "primary_object": { "basename": "DORao73.pdf", "url": "https://authors.library.caltech.edu/records/rphpe-66t70/files/DORao73.pdf" }, "resource_type": "article", "pub_year": "1973", "author_list": "D'Orazio, R. J. and George, Nicholas" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2x5z2-6qc59", "eprint_id": 32870, "eprint_status": "archive", "datestamp": "2023-08-19 08:28:08", "lastmod": "2023-10-18 16:27:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } }, { "id": "Jain-Atul", "name": { "family": "Jain", "given": "Atul" } } ] }, "title": "Speckle Reduction Using Multiple Tones of Illumination", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1973 Optical Society of America.\nReceived 25 September 1972.\nThis work was supported by the Air Force Office of\nScientific Research.\nWe acknowledge that J. H. Wayland's and R. J.\nBing's interest in making holograms of microcirculatory\nblood vessels first stimulated our interest in\nspeckle-free holographic microscopy; also we are\npleased to acknowledge helpful discussions with D.\nMacQuigg and R. B. MacAnally as well as the enthusiastic\nparticipation of Francois Bertiere in the\nfirst series of experiments with the laser sources.\n\nPublished - GEOao73.pdf
", "abstract": "The occurrence and smoothing of speckle are studied as a function of the line width for a highly collimated illuminating source. A general theory is presented for speckling in the image of a partially diffuse, phase type of object, which has a variable number of random scattering centers per resolution element. Then, an expression is derived for the wavelength spacing required to decouple the speckle patterns arising from two monochromatic tones in an imaging system, thereby establishing that it is feasible to smooth speckle using multicolor illumination. This theory is verified in a series of experiments using both laser illumination and band-limited light from a carbon arc. With highly collimated sources, we show that speckle appears laserlike for an imaged diffuser even up to line widths of 5 \u00c5. Then, smoothing of speckle is demonstrated in the imaging of a diffuser and for a section of an optic nerve when the illumination is provided by six narrow lines spread over 1500 \u00c5. Since with color-blind, panchromatic viewing the speckle smooths, a direct extension of this method to holographic microscopy, using a multitone laser, should permit one to record and reconstruct holograms of diffraction-limited resolution that are essentially speckle-free.", "date": "1973-06", "date_type": "published", "publication": "Applied Optics", "volume": "12", "number": "6", "publisher": "Optical Society of America", "pagerange": "1202-1212", "id_number": "CaltechAUTHORS:20120802-092625932", "issn": "0003-6935", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120802-092625932", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)" } ] }, "doi": "10.1364/AO.12.001202", "primary_object": { "basename": "GEOao73.pdf", "url": "https://authors.library.caltech.edu/records/2x5z2-6qc59/files/GEOao73.pdf" }, "resource_type": "article", "pub_year": "1973", "author_list": "George, Nicholas and Jain, Atul" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qwrm4-jz244", "eprint_id": 80275, "eprint_status": "archive", "datestamp": "2023-08-19 07:17:49", "lastmod": "2023-10-17 15:53:04", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Menzies-R-T", "name": { "family": "Menzies", "given": "R. T." } }, { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } }, { "id": "Bhaumik-M-L", "name": { "family": "Bhaumik", "given": "Mani L." } } ] }, "title": "Spectral coincidences between emission lines of the CO laser and absorption lines of nitrogen oxides", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1970 IEEE. \n\nManuscript received June 1970; revised August 18, 1970. \n\nThis work was supported in part by the Air Force Office of Scientific Research and the California Institute of Technology, Pasadena, Calif.\n\nPublished - 01076365.pdf
", "abstract": "Several spectral coincidences between carbon-monoxide laser emission lines and absorption lines of NO and N_2O_4 have been observed, and absorption measurements have been taken. These data are presented and discussed along with similar spectral coincidence observations made previously using the helium-neon and iodine lasers. Other coincidences between CO-laser lines and NO_2 absorption lines are predicted from a study of recently available high-resolution-spectroscopy literature. Due to the narrow line widths of gas-laser lines, the coincidences reported here can be applied to the selective sensing of these constituents in the atmosphere.", "date": "1970-12", "date_type": "published", "publication": "IEEE Journal of Quantum Electronics", "volume": "6", "number": "12", "publisher": "IEEE", "pagerange": "800-802", "id_number": "CaltechAUTHORS:20170810-172738493", "issn": "0018-9197", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-172738493", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)" }, { "agency": "Caltech" } ] }, "doi": "10.1109/JQE.1970.1076365", "primary_object": { "basename": "01076365.pdf", "url": "https://authors.library.caltech.edu/records/qwrm4-jz244/files/01076365.pdf" }, "resource_type": "article", "pub_year": "1970", "author_list": "Menzies, R. T.; George, Nicholas; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e6v7k-nzr10", "eprint_id": 80274, "eprint_status": "archive", "datestamp": "2023-08-19 07:01:24", "lastmod": "2023-10-17 15:53:01", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Menzies-R-T", "name": { "family": "Menzies", "given": "Robert T." } }, { "id": "Dienes-A", "name": { "family": "Dienes", "given": "Andrew" } }, { "id": "George-N-A", "name": { "family": "George", "given": "Nicholas" } } ] }, "title": "Axial magnetic field effects on a saturated He-Ne laser amplifier", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1970 IEEE. \n\nManuscript received June 30, 1969; revised September 8, 1969. \n\nThe work of R. T. Menzies and N. George was supported in part by the Electronics Division of the Air Force Office of Scientific Research. This paper is based in part on partial fulfillment of the by the Ph.D. degree, California Institute of Technology, Pasadena, Calif., by R. T. Menzies.\n\nPublished - 01076384.pdf
", "abstract": "The behavior of a He-Ne laser amplifier in the presence of an axial magnetic field has been studied experimentally by measuring Faraday rotation and gain for various values of input signal intensity. Two high-gain transitions in the 3.39-\u03bc region were used for study-a J = 1 to J = 2 transition and a J = 1 to J = 1 transition. Theoretical expressions have been developed, which included the nonlinear effects of saturation strength signals. Experimental results clearly show saturation of Faraday rotation; in addition, for the J = 1 to J = 1 transition, a Faraday rotation reversal and a traveling-wave magnetic field dip are seen. These results match the theoretical predictions and provide a method for measuring the upper (3_s_2) level quadrupole moment decay rate.", "date": "1970-02", "date_type": "published", "publication": "IEEE Journal of Quantum Electronics", "volume": "6", "number": "2", "publisher": "IEEE", "pagerange": "117-122", "id_number": "CaltechAUTHORS:20170810-171639972", "issn": "0018-9197", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170810-171639972", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/JQE.1970.1076384", "primary_object": { "basename": "01076384.pdf", "url": "https://authors.library.caltech.edu/records/e6v7k-nzr10/files/01076384.pdf" }, "resource_type": "article", "pub_year": "1970", "author_list": "Menzies, Robert T.; Dienes, Andrew; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/znz5g-xff27", "eprint_id": 80390, "eprint_status": "archive", "datestamp": "2023-08-19 06:26:45", "lastmod": "2023-10-17 15:58:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chang-M", "name": { "family": "Chang", "given": "M." } }, { "id": "George-N-A", "name": { "family": "George", "given": "N." } } ] }, "title": "Holographic gratings of arbitrary loss: Theory and experiment", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 1969 IEEE. \n\nThis work was supported by the Electronics Division of the Air Force Office of Scientific Research.\n\nPublished - 01082008.pdf
", "abstract": "Thick lossy dielectric gratings have been analyzed using a Raman-Nath formalism modified to incorporate losses. Four second order coupled-wave equations are retained for accurate computation of the zero; first-, and second-order diffracted beams for a multitude of practical cases. Significant differences are found in comparison to computations in which only two coupled waves are retained. The entire range of losses and thicknesses encountered for holograms in AgBr emulsions has been studied using this unified approach.", "date": "1969-06", "date_type": "published", "publication": "IEEE Journal of Quantum Electronics", "volume": "5", "number": "6", "publisher": "IEEE", "pagerange": "333", "id_number": "CaltechAUTHORS:20170814-162255339", "issn": "0018-9197", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170814-162255339", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)" } ] }, "doi": "10.1109/JQE.1969.1082008", "primary_object": { "basename": "01082008.pdf", "url": "https://authors.library.caltech.edu/records/znz5g-xff27/files/01082008.pdf" }, "resource_type": "article", "pub_year": "1969", "author_list": "Chang, M. and George, N." } ]