{"id":314,"date":"2015-08-25T14:35:00","date_gmt":"2015-08-25T14:35:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/video-equipment\/uncategorized\/video-disc-technologylight-path\/"},"modified":"2015-08-25T14:35:00","modified_gmt":"2015-08-25T14:35:00","slug":"video-disc-technologylight-path","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/video-equipment\/video-disc-technologylight-path\/","title":{"rendered":"VIDEO DISC TECHNOLOGY:LIGHT PATH."},"content":{"rendered":"<div class=\"nggix6a0dbae11f75f\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '61e5902552e2353963d8d2f1bd1f4a8f',\n\t\t'format' : 'iframe',\n\t\t'height' : 250,\n\t\t'width' : 300,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/61e5902552e2353963d8d2f1bd1f4a8f\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.nggix6a0dbae11f75f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.nggix6a0dbae11f75f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.nggix6a0dbae11f75f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.nggix6a0dbae11f75f {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.nggix6a0dbae11f75f {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<h3 align=\"justify\">LIGHT PATH<\/h3>\n<p align=\"justify\">The Laservision disc does not have a turntable as such \u2013 it is clamped at its centre and scanned from below. Fig. 20.2 shows the light path of one type of pick-up which is suitable for both CD-audio and Laser- vision (CLD) players. The laser diode emits a narrow beam of infra- red light whose wavelength is 780 nm. The \ufb01rst component encountered by the light beam is a grating, a glass plate with horizontal lines etched into it. Here the light beam is split into three by a process of diffraction: a bright central one and two secondary beams of lesser intensity. The three closely spaced beams are now  <\/p>\n<p align=\"justify\"><a href=\"http:\/\/lh3.googleusercontent.com\/-ryokRp2Pf0U\/Vdx9H7FNRpI\/AAAAAAAB1jY\/jFVkRnz9Uns\/s1600-h\/DIGITAL-CAMCORDERS-AND-VCRS-02412.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-right-width: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px\" title=\"DIGITAL CAMCORDERS AND VCRS-0241\" border=\"0\" alt=\"DIGITAL CAMCORDERS AND VCRS-0241\" src=\"http:\/\/lh3.googleusercontent.com\/-OBew2lnV5g0\/Vdx9QFmyaQI\/AAAAAAAB1jw\/sxD2GohKm-w\/DIGITAL-CAMCORDERS-AND-VCRS-0241_thu.jpg?imgmax=800\" width=\"244\" height=\"238\" \/><\/a>  <\/p><div class=\"bpzlp6a0dbae11f875\" ><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-0778475562755157\"\n     crossorigin=\"anonymous\"><\/script>\n<!-- 300x600 television-and-video -->\n<ins class=\"adsbygoogle\"\n     style=\"display:inline-block;width:300px;height:600px\"\n     data-ad-client=\"ca-pub-0778475562755157\"\n     data-ad-slot=\"6549443290\"><\/ins>\n<script>\n     (adsbygoogle = window.adsbygoogle || []).push({});\n<\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.bpzlp6a0dbae11f875 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.bpzlp6a0dbae11f875 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.bpzlp6a0dbae11f875 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.bpzlp6a0dbae11f875 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.bpzlp6a0dbae11f875 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"imbmp6a0dbae11f7f8\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '0c1eb4c533eaedb7b996f49a5a4983a9',\n\t\t'format' : 'iframe',\n\t\t'height' : 300,\n\t\t'width' : 160,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/0c1eb4c533eaedb7b996f49a5a4983a9\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.imbmp6a0dbae11f7f8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.imbmp6a0dbae11f7f8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.imbmp6a0dbae11f7f8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.imbmp6a0dbae11f7f8 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.imbmp6a0dbae11f7f8 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\">turned through 90\u00b0 in a half-mirror, which has the characteristic of re\ufb02ecting half the light presented to it and admitting half of it, the latter property being used for the re\ufb02ected beam as we shall see. Next on the light path comes a collimator lens whose job is to capture the diverging light beams and set them on a parallel path towards the re\ufb02ective mirror which turns the beams through 90\u00b0 to direct them to the objective lens. This precision component focuses the three light beams to sharp pin-points of light on the surface of the video disc. The diameter of the focused central spot is less than 1 micron, which is comparable with the wavelength (0.78 micron) of the lightwaves themselves. The outer light spots are used for tracking purposes, and the central one to read out the information on the disc surface.  <\/p>\n<p align=\"justify\">After re\ufb02ection at the disc the light (now modulated) follows the same path in the reverse direction as far as the half-mirror, through which it passes \u2013 with some loss \u2013 to a concave lens. Here its coma distortion is corrected, and it is focused onto the surface of the OEIC (Optical Electronics Integrated Circuit), incorporating a matrix of photodiodes whose outputs provide not only the video and audio signals, but also positional feedback to maintain correct beam focus and tracking during initialisation and play. The operation of the beam focusing servo will now be examined.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>LIGHT PATH The Laservision disc does not have a turntable as such \u2013 it is clamped at its centre and scanned from below. Fig. 20.2 shows the light path of one type of pick-up which is suitable for both CD-audio and Laser- vision (CLD) players. The laser diode emits a narrow beam of infra- red [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/video-equipment\/video-disc-technologylight-path\/\" class=\"more-link\" >Continue reading&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"aioseo_notices":[],"views":601,"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/314"}],"collection":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/comments?post=314"}],"version-history":[{"count":0,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/posts\/314\/revisions"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/media?parent=314"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/categories?post=314"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/video-equipment\/wp-json\/wp\/v2\/tags?post=314"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}