{"id":76,"date":"2018-04-18T19:22:03","date_gmt":"2018-04-18T19:22:03","guid":{"rendered":"https:\/\/live-optics-wp.pantheonsite.io\/oscoutreach\/?p=76"},"modified":"2024-03-28T16:37:18","modified_gmt":"2024-03-28T16:37:18","slug":"peppers-ghost","status":"publish","type":"post","link":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/peppers-ghost\/","title":{"rendered":"Pepper&#8217;s Ghost"},"content":{"rendered":"\n<div class=\"wp-block-group\"><div class=\"wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Overview<\/strong>: Pepper&#8217;s Ghost was popularized in the 1800s and continues to be used today in the entertainment industry, amusement parks, and museums.&nbsp; Aside from being an optical illusion, the technique is also the basis for how teleprompters work.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u200b\u200b<strong>Supplies<\/strong>: Scissors, tape, transparent plastic (printable transparency sheets, CD cases, etc.)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Objectives<\/strong>: What is Pepper&#8217;s Ghost? How does light reflect off a surface? How do teleprompters work?<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Setup:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Print or trace the pattern below onto clear plastic (transparency sheet, CD cases, etc.).&nbsp; Note: the pattern is scaled for a cell-phone screen or tablet.<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"107\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Template-300x107.png\" alt=\"\" class=\"wp-image-121\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Template-300x107.png 300w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Template.png 640w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n<\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>Cut out along the lines, and tape four trapezoids together as shown in the picture below.<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"3024\" height=\"3024\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051.jpg\" alt=\"\" class=\"wp-image-305\" style=\"aspect-ratio:1;width:474px;height:auto\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051.jpg 3024w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051-150x150.jpg 150w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051-300x300.jpg 300w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051-768x768.jpg 768w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051-1024x1024.jpg 1024w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051-90x90.jpg 90w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/IMG_2051-75x75.jpg 75w\" sizes=\"auto, (max-width: 3024px) 100vw, 3024px\" \/><\/figure>\n<\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>Add the last piece of tape between the third and fourth trapezoid to form a pyramid.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>How to run the demo:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Go to this <a rel=\"noopener noreferrer\" href=\"https:\/\/www.youtube.com\/watch?v=CIszi2Kv_lk&amp;feature=youtu.be\" target=\"_blank\">link<\/a>&nbsp;or google &#8220;Pepper&#8217;s Pyramid Videos&#8221; to find a video that you like.&nbsp; The best videos will have a bright foreground and a black background.<\/li>\n\n\n\n<li>Place the center of the pyramid on the center of your screen, turn down the room lights, turn up the brightness on your screen, and play the video.<\/li>\n\n\n\n<li>When viewed edge-on, you will see a &#8220;floating&#8221; image! <\/li>\n<\/ul>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"169\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Jojo-300x169.jpg\" alt=\"\" class=\"wp-image-122\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Jojo-300x169.jpg 300w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Jojo-768x432.jpg 768w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Jojo-1024x576.jpg 1024w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Jojo.jpg 2000w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n<\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>What&#8217;s happening?<\/strong><\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"149\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Peppers-Ghost-Diagram-300x149.png\" alt=\"\" class=\"wp-image-196\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Peppers-Ghost-Diagram-300x149.png 300w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Peppers-Ghost-Diagram-768x381.png 768w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Peppers-Ghost-Diagram-420x210.png 420w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Peppers-Ghost-Diagram.png 884w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">When light from a bright object (produced by the phone or tablet screen) reaches the transparent material, a portion of the light will reflect.&nbsp; For typical plastic, glass, or acrylic, this will be about a 4% reflection.&nbsp; An observer looking at the side of the Pepper&#8217;s Pyramid will then see a virtual image, an object that appears to float inside of the pyramid.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The reflection that you see is from one side of the pyramid.&nbsp; Having four sides allows the illusion to be seen from all angles, and seeing the other edges adds to the illusion that the floating image is contained by the pyramid.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Try this:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Lift up the pyramid off of the screen.&nbsp; Can you still see the image inside?<\/li>\n\n\n\n<li>Flip the pyramid upside down.&nbsp; What happens to the image?<\/li>\n\n\n\n<li>If the pyramid will not stand on its own, try adjusting the sides and tape them together again.<\/li>\n\n\n\n<li>Check out all four sides. Is there a direction where the image is dim or barely visible?&nbsp;This means your screen must be linearly polarized!<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Tips:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Be sure the screen is as bright as possible for the best image, and that the video is playing at fullscreen.<\/li>\n\n\n\n<li>The phone-sized pyramid can be folded to be safely carried in your wallet!<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1920\" height=\"2560\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/D8D819FB-F970-4354-B13B-4B1143F9F25B-scaled.jpeg\" alt=\"\" class=\"wp-image-609\" style=\"aspect-ratio:0.75;width:259px;height:auto\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/D8D819FB-F970-4354-B13B-4B1143F9F25B-scaled.jpeg 1920w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/D8D819FB-F970-4354-B13B-4B1143F9F25B-225x300.jpeg 225w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/D8D819FB-F970-4354-B13B-4B1143F9F25B-768x1024.jpeg 768w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/D8D819FB-F970-4354-B13B-4B1143F9F25B-1152x1536.jpeg 1152w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/D8D819FB-F970-4354-B13B-4B1143F9F25B-1536x2048.jpeg 1536w\" sizes=\"auto, (max-width: 1920px) 100vw, 1920px\" \/><\/figure>\n<\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<p class=\"wp-block-paragraph\"><em>Note: This is <strong>not<\/strong> a hologram!<\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In optics, the word &#8220;hologram&#8221; indicates that there is encoded phase information.&nbsp; An entire scene can be captured by a hologram such that an image changes with different viewpoint, and the creation of a hologram requires a recording medium and two separate laser beams.&nbsp; These Pepper&#8217;s pyramid projectors use reflection to create a virtual image and are not technically holograms, though they will be commonly recognized as &#8220;holograms&#8221; in popular culture.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Real-World Applications<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Teleprompters<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter\"><img loading=\"lazy\" decoding=\"async\" width=\"780\" height=\"348\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Teleprompter.png\" alt=\"\" class=\"wp-image-307\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Teleprompter.png 780w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Teleprompter-300x134.png 300w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Teleprompter-768x343.png 768w\" sizes=\"auto, (max-width: 780px) 100vw, 780px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Entertainment Industry<\/p>\n<\/div><\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\"><div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"632\" height=\"768\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/27AAED1B-CB85-4D88-B29F-2039C1F895E9_1_105_c-e1594605641421.jpeg\" alt=\"\" class=\"wp-image-710\" style=\"aspect-ratio:0.895;width:261px;height:auto\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/27AAED1B-CB85-4D88-B29F-2039C1F895E9_1_105_c-e1594605641421.jpeg 632w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/27AAED1B-CB85-4D88-B29F-2039C1F895E9_1_105_c-e1594605641421-247x300.jpeg 247w\" sizes=\"auto, (max-width: 632px) 100vw, 632px\" \/><\/figure>\n<\/div><\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\"><div class=\"wp-block-image\">\n<figure class=\"aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"665\" height=\"768\" src=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/835E4E54-29D2-42C9-92AD-F45700445E30_1_105_c-e1594605727589.jpeg\" alt=\"\" class=\"wp-image-709\" style=\"aspect-ratio:0.9053398058252428;width:261px;height:auto\" srcset=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/835E4E54-29D2-42C9-92AD-F45700445E30_1_105_c-e1594605727589.jpeg 665w, https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2020\/07\/835E4E54-29D2-42C9-92AD-F45700445E30_1_105_c-e1594605727589-260x300.jpeg 260w\" sizes=\"auto, (max-width: 665px) 100vw, 665px\" \/><\/figure>\n<\/div><\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-css-opacity\" \/>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>To learn more:<\/strong> (external links)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.youtube.com\/watch?v=GyKyacqXEpI&amp;list=PL6DwVv2hudGZHkS34wAV-4NQ7Fw3zPTxf&amp;index=31\">Pepper&#8217;s Pyramid demo<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This activity was inspired by DaNel Hogan of <a href=\"https:\/\/stemazing.org\/stem-on-the-cheap\/\">The STEMAZing&nbsp;Project<\/a>, including their #STEMonthecheap initiative.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-content\/uploads\/sites\/75\/2018\/04\/Peppers_Ghost_Page_Template_Isela.pdf\">Full Page Template<\/a> for printing pyramids sized for cell phones. Tip: Print in &#8220;actual size&#8221; and cut edge-to-edge to minimize wasted space.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.amazon.com\/Apollo-Transparency-Printers-Sheets-CG7060\/dp\/B0040YC7FI\/ref=sr_1_3?ie=UTF8&amp;qid=1540008395&amp;sr=8-3&amp;keywords=transparency+paper\">Laser Printer Transparency Film<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/arstechnica.com\/science\/2012\/04\/tupac-hologram-merely-pretty-cool-optical-illusion\/\">&#8220;Tupac &#8216;hologram&#8217; merely pretty cool optical illusion&#8221;<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.smithsonianmag.com\/history\/a-brief-history-of-the-teleprompter-88039053\/\">History of the teleprompter<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.optics.arizona.edu\/sites\/default\/files\/2022-07\/Pepper%27s%20Ghost%20Pamphlet.pdf\">Pepper&#8217;s Pyramid take home pamphlet<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Make images float in midair.<\/p>\n","protected":false},"author":43,"featured_media":122,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-76","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-optical-illusion"],"_links":{"self":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts\/76","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/users\/43"}],"replies":[{"embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/comments?post=76"}],"version-history":[{"count":23,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts\/76\/revisions"}],"predecessor-version":[{"id":1750,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/posts\/76\/revisions\/1750"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/media\/122"}],"wp:attachment":[{"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/media?parent=76"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/categories?post=76"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wp.optics.arizona.edu\/oscoutreach\/wp-json\/wp\/v2\/tags?post=76"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}