Isentropic compression of thermonuclear fuel pellets in laser fusion systems requires a laser pulse with a faster-than-exponential rise in intensity. One method of producing such pulses, known as pulse-stacking, consists of generating a sequence of pulses with appropriate amplitudes and recombining them with appropriate time delays to form an approximation to the required pulse shape. Numerous active and passive pulse-stacking systems have been proposed, although adequate documentation on these is almost entirely lacking. In this report we analyze the performance characteristics of several of the better-documented systems: the Thomas-KMS fusion pulse-stacker,1 the Pockels cell pulse-stacker of Harney,2 and the Emmett-LLL pulse-stacker.3 These systems are typical of the best suggestions to date and are shown schematically in Figs. 1(a)-(c).
{"title":"Analysis of the fusion-effectiveness of active and passive pulse-stackers","authors":"R. Harney, J. Schipper","doi":"10.1364/cleos.1976.thd3","DOIUrl":"https://doi.org/10.1364/cleos.1976.thd3","url":null,"abstract":"Isentropic compression of thermonuclear fuel pellets in laser fusion systems requires a laser pulse with a faster-than-exponential rise in intensity. One method of producing such pulses, known as pulse-stacking, consists of generating a sequence of pulses with appropriate amplitudes and recombining them with appropriate time delays to form an approximation to the required pulse shape. Numerous active and passive pulse-stacking systems have been proposed, although adequate documentation on these is almost entirely lacking. In this report we analyze the performance characteristics of several of the better-documented systems: the Thomas-KMS fusion pulse-stacker,1 the Pockels cell pulse-stacker of Harney,2 and the Emmett-LLL pulse-stacker.3 These systems are typical of the best suggestions to date and are shown schematically in Figs. 1(a)-(c).","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125449415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laser amplifiers designed for use in laser fusion systems must necessarily meet stringent gain uniformity requirements in order to avoid impairing the laser beam apodization. Since the intensity profile of the laser beam directly affects the illumination uniformity (and hence the implosion symmetries) of laser fusion targets, it is essential that the individual laser amplifiers in each amplifier chain have high gain and highly uniform gain distributions. For large aperture glass laser rod amplifiers, this is difficult to achieve since the pumping radiation from the flashlamps must pass through the outer portions of the laser rod before the axis can be pumped.
{"title":"Design techniques and measured performance for a uniformly pumped 4-cm diam rod amplifier","authors":"G. Linford, S. Yarema","doi":"10.1364/cleos.1976.tha4","DOIUrl":"https://doi.org/10.1364/cleos.1976.tha4","url":null,"abstract":"Laser amplifiers designed for use in laser fusion systems must necessarily meet stringent gain uniformity requirements in order to avoid impairing the laser beam apodization. Since the intensity profile of the laser beam directly affects the illumination uniformity (and hence the implosion symmetries) of laser fusion targets, it is essential that the individual laser amplifiers in each amplifier chain have high gain and highly uniform gain distributions. For large aperture glass laser rod amplifiers, this is difficult to achieve since the pumping radiation from the flashlamps must pass through the outer portions of the laser rod before the axis can be pumped.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"167 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126583085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The SHIVA high energy laser facility now under construction at Lawrence Livermore Laboratory is a 20-arm, 1.06-µm Nd-glass laser system that can focus 20-30 TW of power nearly uniformly on a 300-1500-µm diam deuterium-tritium laser fusion pellet. The facility will be in operation in 1977 and should produce significant thermonuclear burn (fusion energy output = 1 % light energy input).
{"title":"Focusing lenses for the 20-beam fusion laser: SHIVA","authors":"W. O'Neal","doi":"10.1364/cleos.1976.tha9","DOIUrl":"https://doi.org/10.1364/cleos.1976.tha9","url":null,"abstract":"The SHIVA high energy laser facility now under construction at Lawrence Livermore Laboratory is a 20-arm, 1.06-µm Nd-glass laser system that can focus 20-30 TW of power nearly uniformly on a 300-1500-µm diam deuterium-tritium laser fusion pellet. The facility will be in operation in 1977 and should produce significant thermonuclear burn (fusion energy output = 1 % light energy input).","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131063252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Measurements at Los Alamos Scientific Laboratories have shown1 that, when a high energy (larger than 5G) nanosecond pulse at 10.6 μm is focused into a target, 5% of the incident energy is back-scattered into the laser source. (The measurements were performed at grazing incidence.) As the reflected pulse propagates back into the amplifier chain, its intensity will increase because of (1) the residual gain of the amplifiers and (2) the converging (for the direction of the reflected pulse) optic of the chain. The latter mechanism alone is sufficient to lead to destruction of components in the optical chain since the ratio of the oscillator to the amplifier diameter is about 10−1.
{"title":"Isolation of high-power multiline CO2 laser amplifier chains from the target reflection","authors":"J. Diels, M. Bass","doi":"10.1364/cleos.1976.wg4","DOIUrl":"https://doi.org/10.1364/cleos.1976.wg4","url":null,"abstract":"Measurements at Los Alamos Scientific Laboratories have shown1 that, when a high energy (larger than 5G) nanosecond pulse at 10.6 μm is focused into a target, 5% of the incident energy is back-scattered into the laser source. (The measurements were performed at grazing incidence.) As the reflected pulse propagates back into the amplifier chain, its intensity will increase because of (1) the residual gain of the amplifiers and (2) the converging (for the direction of the reflected pulse) optic of the chain. The latter mechanism alone is sufficient to lead to destruction of components in the optical chain since the ratio of the oscillator to the amplifier diameter is about 10−1.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130050940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Single particle optical counters, which operate on the principle of light scattering, are useful for in situ aerosol size analysis. Several commercial counters were calibrated using ideal and nonideal aerosols. Ideal aerosols with a spherical, smooth surface were generated either by nebulizing PSL suspensions or by feeding solutions of DOP or Cargille index-of-refraction liquids into a vibrating orifice generator. Nonideal, light-absorbing particles of irregular shape were generated by the same vibrating orifice or by a fluidized bed.
{"title":"Aerosol sizing by optical means","authors":"K. Willeke, Benjamin Y. H. Liu, K. T. Whitby","doi":"10.1364/cleos.1976.tuf1","DOIUrl":"https://doi.org/10.1364/cleos.1976.tuf1","url":null,"abstract":"Single particle optical counters, which operate on the principle of light scattering, are useful for in situ aerosol size analysis. Several commercial counters were calibrated using ideal and nonideal aerosols. Ideal aerosols with a spherical, smooth surface were generated either by nebulizing PSL suspensions or by feeding solutions of DOP or Cargille index-of-refraction liquids into a vibrating orifice generator. Nonideal, light-absorbing particles of irregular shape were generated by the same vibrating orifice or by a fluidized bed.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117298285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gabor has described1 the dark-field method as a means of improving the reconstructed image by eliminating the disturbance caused by the ghost image when the object is in the Fresnel region. The reconstructed image was filtered by placing an apodized dark spot at the real image of the pinhole of the reconstruction source, thus removing the rays of light undiffracted by the object.
{"title":"Holographic recording of magnified dark-field images","authors":"M. L. Gassend, Kim I. Davis, W. Boerner","doi":"10.1364/cleos.1976.wc4","DOIUrl":"https://doi.org/10.1364/cleos.1976.wc4","url":null,"abstract":"Gabor has described1 the dark-field method as a means of improving the reconstructed image by eliminating the disturbance caused by the ghost image when the object is in the Fresnel region. The reconstructed image was filtered by placing an apodized dark spot at the real image of the pinhole of the reconstruction source, thus removing the rays of light undiffracted by the object.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128296971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Wisner, A. Angelbeck, B. A. Woody, A. Greiner, R. Freeman, H. C. Reynolds
Adaptive optical techniques have been employed to track target glint returns using two-axis steering and focus correction. Measurements were made on laboratory apparatus, operating at 10.6 µm. The apparatus consists of a low power CO2 laser, a 300-Hz bandwidth wavefront manipulator, focusing optics to form a far-field beam pattern, a moving glint (a small polished sphere), and an on-axis receiver that views target return. Adaptive control is implemented by tagging each correction mode with a high-frequency low-amplitude dither which is a small fraction of the available mode range. Classical hill-climbing servos are used to maximize glint return by nulling the dither component of each correction at a zero slope point corresponding to maximum target power.
{"title":"Glint tracking using adaptive optical techniques","authors":"G. Wisner, A. Angelbeck, B. A. Woody, A. Greiner, R. Freeman, H. C. Reynolds","doi":"10.1364/cleos.1976.thf6","DOIUrl":"https://doi.org/10.1364/cleos.1976.thf6","url":null,"abstract":"Adaptive optical techniques have been employed to track target glint returns using two-axis steering and focus correction. Measurements were made on laboratory apparatus, operating at 10.6 µm. The apparatus consists of a low power CO2 laser, a 300-Hz bandwidth wavefront manipulator, focusing optics to form a far-field beam pattern, a moving glint (a small polished sphere), and an on-axis receiver that views target return. Adaptive control is implemented by tagging each correction mode with a high-frequency low-amplitude dither which is a small fraction of the available mode range. Classical hill-climbing servos are used to maximize glint return by nulling the dither component of each correction at a zero slope point corresponding to maximum target power.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126240742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Intensity-dependent changes in the refractive index of optical materials associated with the propagation of intense laser beams cause self-focusing and beam breakup and a resultant loss of focusable energy. For long amplifier chains, such as used in Nd-glass fusion lasers, beam degradation originates in many transmissive elements. These include the lasing medium, lenses, windows, polarizer substrates, Faraday rotators, and nonlinear crystals. The beam degradation is proportional to n2/n(n − 1) for lenses, to n2/n for laser rods, windows, and rotators oriented normal to the beam, and to n2/n2 for laser disks at Brewster’s angle, where n and n2 are, respectively, the linear and nonlinear refractive indices. In all cases low n2 values are desirable. Accurate data on n2 is required for optimum staging of components in high-power laser systems.
{"title":"Time-resolved interferometric technique and measurements of the nonlinear refractive index of laser materials","authors":"D. Milam, M. Weber","doi":"10.1364/cleos.1976.tha6","DOIUrl":"https://doi.org/10.1364/cleos.1976.tha6","url":null,"abstract":"Intensity-dependent changes in the refractive index of optical materials associated with the propagation of intense laser beams cause self-focusing and beam breakup and a resultant loss of focusable energy. For long amplifier chains, such as used in Nd-glass fusion lasers, beam degradation originates in many transmissive elements. These include the lasing medium, lenses, windows, polarizer substrates, Faraday rotators, and nonlinear crystals. The beam degradation is proportional to n2/n(n − 1) for lenses, to n2/n for laser rods, windows, and rotators oriented normal to the beam, and to n2/n2 for laser disks at Brewster’s angle, where n and n2 are, respectively, the linear and nonlinear refractive indices. In all cases low n2 values are desirable. Accurate data on n2 is required for optimum staging of components in high-power laser systems.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122487112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Previously we have reported on the LiNbO3 angle tuned parametric oscillator and its potential for computer control and operation as a coherent spectrometer.1 In this paper we report the operation of the parametric oscillator under full interactive computer control. The present system allows the user to choose the starting wavelength, scan range, scan rate, and resolution. The computer controls the stepper motors that rotate the LiNbO3 crystal and line narrowing grating. The user can also designate a data file for recording the spectral data on disk for later display on an x-y recorder. With the present system we have generated a coherent anti-Stokes spectrum2 of H2 gas at gas pressures from 1 atm to below 10 Torr. The absolute wavelength resettability of the parametric tuner determined from the spectrum was ±0.2 cm−1 at a resolution of 2 cm−1. Additional line narrowing with an etalon led to line-widths of less than 0.2 cm−1.
{"title":"Computer controlled infrared parametric oscillator source","authors":"S. Brosnan, R. Fleming, R. Herbst, R. Byer","doi":"10.1364/cleos.1976.wc11","DOIUrl":"https://doi.org/10.1364/cleos.1976.wc11","url":null,"abstract":"Previously we have reported on the LiNbO3 angle tuned parametric oscillator and its potential for computer control and operation as a coherent spectrometer.1 In this paper we report the operation of the parametric oscillator under full interactive computer control. The present system allows the user to choose the starting wavelength, scan range, scan rate, and resolution. The computer controls the stepper motors that rotate the LiNbO3 crystal and line narrowing grating. The user can also designate a data file for recording the spectral data on disk for later display on an x-y recorder. With the present system we have generated a coherent anti-Stokes spectrum2 of H2 gas at gas pressures from 1 atm to below 10 Torr. The absolute wavelength resettability of the parametric tuner determined from the spectrum was ±0.2 cm−1 at a resolution of 2 cm−1. Additional line narrowing with an etalon led to line-widths of less than 0.2 cm−1.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"151 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133806934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One method of laser isotope separation requires a far FIR, nearly monochromatic source of radiation having an energy per pulse on the order of tens of microjoules. An attractive method of producing this required energy is difference frequency generation using a CO and a CO2 laser as sources.1,2 The difference frequency generation could occur in a nonlinear material such as CdGeAs2 or AgGaSe2. The engineering development of the lasers and the results obtained from second harmonic generation as well as difference frequency generation experiments are described. The major emphasis in the development of the CO laser was the increase in the peak power. However, the major emphasis in the development of the CO2 laser was the attainment of consistently good spatial and temporal mode quality.
{"title":"Far infrared difference frequency generation","authors":"N. Barnes, R. Nickle, P. Mace","doi":"10.1364/cleos.1976.thd8","DOIUrl":"https://doi.org/10.1364/cleos.1976.thd8","url":null,"abstract":"One method of laser isotope separation requires a far FIR, nearly monochromatic source of radiation having an energy per pulse on the order of tens of microjoules. An attractive method of producing this required energy is difference frequency generation using a CO and a CO2 laser as sources.1,2 The difference frequency generation could occur in a nonlinear material such as CdGeAs2 or AgGaSe2. The engineering development of the lasers and the results obtained from second harmonic generation as well as difference frequency generation experiments are described. The major emphasis in the development of the CO laser was the increase in the peak power. However, the major emphasis in the development of the CO2 laser was the attainment of consistently good spatial and temporal mode quality.","PeriodicalId":301658,"journal":{"name":"Conference on Laser and Electrooptical Systems","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116535634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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