{"id":1142,"date":"2011-03-11T16:54:02","date_gmt":"2011-03-11T16:54:02","guid":{"rendered":"http:\/\/labrigger.com\/blog\/?p=1142"},"modified":"2011-03-11T16:54:02","modified_gmt":"2011-03-11T16:54:02","slug":"laser-pointers-and-quantum-mechanics","status":"publish","type":"post","link":"http:\/\/labrigger.com\/blog\/2011\/03\/11\/laser-pointers-and-quantum-mechanics\/","title":{"rendered":"Laser pointers and quantum mechanics"},"content":{"rendered":"<p align=\"center\"><a href=\"http:\/\/arxiv.org\/abs\/1008.1452\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/glpmca1_sm.png\" alt=\"\" title=\"A diagram for a typical green laser pointer. Note that it is a diode-pumped solid state laser. The IR lines are typically included in the output beam. Click for source.\" width=\"600\" height=\"529\" class=\"aligncenter size-full wp-image-1145\" srcset=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/glpmca1_sm.png 600w, http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/glpmca1_sm-300x264.png 300w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/a><\/p>\n<p>Laser pointers are handy sources for coherent light. The green and blue varieties are actually diode-pumped solid state lasers, all in a hand-held package. The IR wavelengths used for pumping are typically left in the beam, so your green laser pointer is actually a fairly bright IR laser with some green thrown in.<\/p>\n<p>This was discussed in a NIST technical note (<a href=\"http:\/\/arxiv.org\/abs\/1008.1452\">arXiv<\/a>). Here&#8217;s the spectrum for a green laser pointer they measured. Note that it&#8217;s way hotter in the IR than in green.<\/p>\n<p align=\"center\"><a href=\"http:\/\/arxiv.org\/abs\/1008.1452\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/green-laser-pointer-spectrum.png\" alt=\"\" title=\"Figure is from http:\/\/arxiv.org\/abs\/1008.1452 Click for source.\" width=\"503\" height=\"476\" class=\"aligncenter size-full wp-image-1144\" srcset=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/green-laser-pointer-spectrum.png 503w, http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/green-laser-pointer-spectrum-300x283.png 300w\" sizes=\"auto, (max-width: 503px) 100vw, 503px\" \/><\/a><\/p>\n<p>Besides imaging and aligning optics (and, apparently, pointing), they&#8217;re useful for demonstrating different physical properties of light. <\/p>\n<p>I rather enjoyed <a href=\"http:\/\/occamstypewriter.org\/rpg\/2011\/03\/01\/on-the-hairy-nature-of-light\/\">rpg&#8217;s post<\/a> on using a laser pointer to investigate the wave nature of light. Key quote:<em> &#8220;So the wavelength of my laser is about 500 nm. Seeing as it\u2019s rated as 532 nm and I\u2019m a biologist, I\u2019d call that a result.&#8221;<\/em> The basic idea is to replicate <a href=\"http:\/\/en.wikipedia.org\/wiki\/Double-slit_experiment\">Young&#8217;s classic double-slit experiment<\/a> using a laser pointer as the coherent source.<\/p>\n<p>It reminded me of this old <a href=\"http:\/\/www.scientificamerican.com\/article.cfm?id=slide-show-do-it-yourself-diy-quantum-eraser\">Scientific American article<\/a> about how you can make your own <a href=\"http:\/\/en.wikipedia.org\/wiki\/Quantum_eraser_experiment\">Quantum Eraser<\/a>. <\/p>\n<p align=\"center\"><a href=\"http:\/\/www.scientificamerican.com\/article.cfm?id=slide-show-do-it-yourself-diy-quantum-eraser\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/qe1.png\" alt=\"\" title=\"A DIY quantum eraser. From Scientific American. Click for source.\" width=\"496\" height=\"208\" class=\"aligncenter size-full wp-image-1146\" srcset=\"http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/qe1.png 496w, http:\/\/labrigger.com\/blog\/wp-content\/uploads\/2011\/03\/qe1-300x125.png 300w\" sizes=\"auto, (max-width: 496px) 100vw, 496px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p align=\"center\"><a href=\"http:\/\/arxiv.org\/abs\/1008.1452\"><\/a><\/p>\n<p>Laser pointers are handy&#8230;<\/p>\n<div class=\"read-more\"><a href=\"http:\/\/labrigger.com\/blog\/2011\/03\/11\/laser-pointers-and-quantum-mechanics\/\">Read More<\/a><\/div><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[13,32,20],"class_list":["post-1142","post","type-post","status-publish","format-standard","hentry","category-hardware","tag-gadgets","tag-laser","tag-references"],"_links":{"self":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/1142","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/comments?post=1142"}],"version-history":[{"count":5,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/1142\/revisions"}],"predecessor-version":[{"id":1150,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/1142\/revisions\/1150"}],"wp:attachment":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/media?parent=1142"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/categories?post=1142"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/tags?post=1142"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}