The interaction of CO<sub>2</sub>laser radiation with various solid targets

Dyer, P. E.; Ramsden, S.A.; Sayers, J. A.; Skipper, Mark

doi:10.1088/0022-3727/9/3/003

Cited by 30 publications

(3 citation statements)

References 16 publications

(14 reference statements)

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“…The reflectivity is qualitatively compatible with numerical predictions of strong optical resonance absorption plus inverse bremsstrahlung in inhomogeneous plasmas. 18 In common with other experiments using gain-switched transverse-excitation atmosphere lasers, 15 the absolute reflectivity was found to be insensitive to target material and incident radiation intensity (within the range 3x lO^-lO 13 are noteworthy: (i) Radiation is scattered into preferred angles (Fig. 3); (ii) its intensity is strongly modulated 2 * 6 [ Fig.…”

supporting

confidence: 60%

Reflection and Scattering from CO2-Laser-Generated Plasmas

1976

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The intensity of 10.6-^m radiation scattered from carbon plasmas has been measured as a function of incidence and collection angles (with angular resolution ^1 0 3°), and of laser mode structure. Over an incident intensity range lO^-lO 13 W cm" 2 , total reflectivity was typically ^>8%. At certain angles, reflectivity often showed 100% temporal modulation. The relevance of these results to critical-surface and stimulated-scattering phenomena is discussed.The reflection and scattering of radiation from laser-produced plasmas is a topic of active experimental and theoretical interest. Extensive measurements on a wide variety of targets have been reported, for example, at wavelengths of X = 0.694/ 1.06, 2 " 7 and 10.6 juim. 8 " 15 In most of these experiments the focusing arrangements were such that the target simultaneously encountered a wide range of angles of incidence (0). This Letter describes measurements made with angular resolution higher than those in previous work, 5 * 12 and discusses the exceptionally strong time variation of reflectivity which has been observed with use of multimode lasers and the absence of detectable modulation when a laser is operated on a single transverse axial mode.As shown in Fig. 1, a 75-J, 50-ns pulse from a plane-polarized multimode C0 2 laser of cross section 5 cmx 10 cm was focused by a 7.8-cmdiam (//4.4), 22-cm-focal-length, KC1 lens onto a solid-graphite target. Radiation backscattered into the focusing lens, and the incident radiation, were sampled by a 16% NaCl beam splitter and imaged onto photon-drag detectors PD2 and PDl. Radiation sidescattered into the remaining ~2.07r ster was collected by a spherical copper mirror and focused into a photon-drag detector PD3 lon, Back scattered photon drag PD2 cated behind the target. Variations of absorption with 6 were investigated by placing annular apertures at the laser output window (thus restricting the uncertainty in 101 to 0.65°-1.3°) while the backscattered and sidescattered signals were measured into the collection angles of the lens and mirror, respectively. Similarly, the distribution of radiation scattered into angles cp±Acp was measured (with the full //4.4 cone of radiation incident) by placing a series of annular apertures before the PD2 imaging lens, giving a resolution Acp = 0.4°-0.8°

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confidence: 60%

Reflection and Scattering from CO2-Laser-Generated Plasmas

1976

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“…Finally, the energy balance results are in reasonable agreement with previously published work, which has however been mainly confined to measurements of backscatter through focusing optics. Reflectivities of between 3-10 % have been variously reported for carbon (Donaldson et a1 1976, Hall andNegm 1976) and polyethylene (Dyer et al 1976, Stenz et al 1977, Dick and Pepin 1975, Baldis and Neufeld 1975 targets using 40-60 ns CO2 laser pulses at irradiances of 1011-1012 W cm-2. The comparable value in these experiments of 2 % fits an apparent trend of increasing backscatter with decreasing f number.…”

Section: Optical Measurements and Discussion Of Resultsmentioning

confidence: 92%

The heating of polyethylene pellets with kilojoule, microsecond duration, CO₂laser pulses

Walker¹,

Stamatakis²,

Spalding

1978

J. Phys. D: Appl. Phys.

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The energy absorption of 1-1.6 kJ gain-switched CO2 laser pulses focused by an approximately f/22 mirror to a spot of innermost diameter 300 mu m (FWHM) on 0.5 and 1 mm suspended cubes of polyethylene has been measured to be 75+or-13%. For plane targets the absorption was also encouragingly high, 71+or-10%. The relative insensitivity of refraction and other losses to pellet size (vis-a-vis previous short-pulse Nd laser experiments) are fully consistent with the ruby laser shadowgram and interferogram observations made towards the end of the 1.5 mu s CO2 pulse, which reveal dense cold material expanding almost randomly at velocities of approximately 0.5 mm mu s-1.

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“…When, in the mid-1970s, Doug James moved to a post in Canada, Dr. Peter Dyer took over the group. The TEA CO 2 laser work continued to evolve [122] , and investigations of the newly emerging discharge-excited excimer lasers commenced. The nanosecond UV excimer lasers were found to be excellent tools for micromachining various materials by ablation.…”

Section: University Of Hullmentioning

confidence: 99%

A history of high-power laser research and development in the United Kingdom

Danson

White

Barr

et al. 2021

High Pow Laser Sci Eng

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The first demonstration of laser action in ruby was made in 1960 by T. H. Maiman of Hughes Research Laboratories, USA. Many laboratories worldwide began the search for lasers using different materials, operating at different wavelengths. In the UK, academia, industry and the central laboratories took up the challenge from the earliest days to develop these systems for a broad range of applications. This historical review looks at the contribution the UK has made to the advancement of the technology, the development of systems and components and their exploitation over the last 60 years.

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The interaction of CO₂laser radiation with various solid targets

Cited by 30 publications

References 16 publications

Reflection and Scattering from CO2-Laser-Generated Plasmas

Reflection and Scattering from CO2-Laser-Generated Plasmas

The heating of polyethylene pellets with kilojoule, microsecond duration, CO₂laser pulses

A history of high-power laser research and development in the United Kingdom

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The interaction of CO2laser radiation with various solid targets

Cited by 30 publications

References 16 publications

Reflection and Scattering from CO2-Laser-Generated Plasmas

Reflection and Scattering from CO2-Laser-Generated Plasmas

The heating of polyethylene pellets with kilojoule, microsecond duration, CO2laser pulses

A history of high-power laser research and development in the United Kingdom

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Product

Resources

About

The interaction of CO₂laser radiation with various solid targets

The heating of polyethylene pellets with kilojoule, microsecond duration, CO₂laser pulses