Patent GB-1137291-A (GB)
Title: Apparatus for the development of a coherent monochromatic light beam
IPC: H01S3/00
Filed: 1966-01-04
Abstract: 1,137,291. Lasers. RINGSDORFF-WERKE G.m.b.H. 4 Jan., 1966 [23 June, 1965], No. 321/66. Heading H1C. A monochromatic coherent light beam is obtained by arranging a plurality of lasers to emit output pulses in sequence and positioning a rotating mirror in the paths of the output light pulses so as to reflect the pulses from at least one of the lasers. In the basic arrangement of Fig. 1 (not shown), and Fig. 2, a rotatably mounted support 1 driven by a wheel 2 has a smooth reflecting surface 4 forming a segment of a conical surface extending along a part of its periphery. One laser L1 is positioned in the same plane as the support so that its output beam can be reflected by the reflecting surface and a second laser L2 is positioned at right angles to the first laser so that its output beam can pass when the reflecting surface is not in a position to reflect the first laser's L1 light output. The lasers are pumped so that the pulses of the lasers are in an alternating pulsed relationship to each other and the reflecting surface is rotated to and fro so that the output beam, in line with the output from the second laser L2, occurs when the surface is in alignment with the laser L1 and when it is moved out of alignment with this laser to allow the light from the second laser L2 to pass. The output is in the form of separated pulses Fig. 10 (not shown). In the arrangement of Fig. 3 (not shown), reflecting surfaces are positioned at regular intervals around the periphery of the support 1 which in operation is rotated in one direction only so that the reflecting surfaces alternately block the path of the second laser L2 and reflect the pulses of the first laser L1 The pulse frequency of the output beam is thus increased, Fig. 11 (not shown). In the arrangement of Figs. 4, 5 (not shown), two lasers L3, L4 are arranged in parallel spaced planes facing each other and the output beam from each laser is directed on to a separate reflecting surface each supported by a rotated support. The reflecting surfaces are inclined such that they direct the laser output beams into a common output beam at right angles to the output beams from the lasers. The resultant output beam is a series of overlapping pulses, Fig. 12 (not shown). The number of lasers can be increased, Fig. 6 (not shown), and Fig. 7, wherein ten lasers are positioned in a helical path around a central axis Al 1-10 , only two L9, L10 being shown. The laser L10 sends its single output beam directly along axis Al 1-10  and the remaining lasers are arranged in parallel planes around this axis, each being provided with a reflection unit comprising a rotatable support 9 provided with a conical reflector 10. The rotation of the supports 9 is by respective gearings 11 and is synchronized to the frequency of the output pulses from the lasers and the output beam is in the form of a series of overlapping pulses. In Fig. 8 (not shown), a rotatable disc is provided having reflecting surfaces arranged at intervals along the periphery of the disc and inclined variably with respect to the main surface of the disc with angles α, #, γ. Three lasers L1, L2, L3 are provided which direct their output beams on to a common point on the reflecting surfaces and the arrangement is such that the light from laser L1 is reflected along a common output beam path when the portion inclined at angle α is opposite thereto, light from laser L2, is reflected when the portion inclined at # is opposite thereto and light from laser L3 when the portion inclined at γ is opposite thereto. The arrangement of Fig. 9 (not shown) employs two pairs of lasers L 1 <SP>1</SP>, L 1 <SP>11</SP> and L 2 <SP>1</SP>, L 2 1<SP>1</SP>, each pair being coaxial and arranged to each other so that their output beams travel along the same line but in opposite directions. Reflecting surfaces are arranged at the periphery of a rotatable disc positioned to intersect the outputs from the lasers, in a toothlike fashion and with opposed inclinations to each other. The speed of rotation of the disc is synchronized with the pulse frequency of the lasers so that two output beams are obtained one from each pair of lasers.