{"id":834,"date":"2010-11-06T00:53:12","date_gmt":"2010-11-06T00:53:12","guid":{"rendered":"http:\/\/labrigger.com\/blog\/?p=834"},"modified":"2010-11-06T00:53:12","modified_gmt":"2010-11-06T00:53:12","slug":"cameras-for-ultra-low-light-levels","status":"publish","type":"post","link":"http:\/\/labrigger.com\/blog\/2010\/11\/06\/cameras-for-ultra-low-light-levels\/","title":{"rendered":"Cameras for ultra low light levels"},"content":{"rendered":"

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Many image sensors are built backwards, just like the retina. The actual photon detectors are buried behind a mesh of circuitry. Back-illuminated sensors, where the detectors are put in front, were a big step forward for light-limited applications. Now they’re so common, even the iPhone 4 has a back-illuminated CMOS camera. A couple of other big steps forward were intensified CCDs and electron multiplying CCDs.<\/p>\n

In electron multiplying CCDs (EMCCDs<\/a>) (some nice tutorials<\/a>) the signal is amplified on chip, just prior to reading. So read noise is vastly improved. Of course, the dark noise is also amplified, but in practice this hasn’t been a large limitation. At low light levels, their main competitor is intensified CCDs (ICCDs). When imaging fast, and with around 10 photons\/pixel, it’s a hard call whether to go with an ICCD or an EMCCD. The EMCCD needs aggressive cooling and does better with slower frame rates, but the ICCD has only a 50% QE compared to the >90% QE of EMCCDs. There are some analyses of the signal-to-noise ratio under different circumstances in ICCDs and EMCCDs (e.g., this<\/a>, this<\/a>, and this pdf<\/a>), but it’s a thorny issue. I recommend you demo both. Also keep in mind that EMCCDs age in response to usage of the high gain modes (pdf<\/a>).<\/p>\n

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These products aren’t to market yet, but they’re something to keep an eye on: micro single photon detectors. Philips has an 8×8 array<\/a> of avalanche photodiodes, which has on-chip amplifiers and photon counting. Hamamatsu has a MEMS PMT<\/a>. Among other things, this technology raises the possibility of an image sensor with 120 dB of dynamic range.<\/p>\n

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Many image sensors are built backwards, just like the retina. The actual photon detectors are buried behind a mesh of circuitry. Back-illuminated sensors, where the detectors are put…<\/p>\n

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":[31,21],"class_list":["post-834","post","type-post","status-publish","format-standard","hentry","category-hardware","tag-equipment","tag-imaging"],"_links":{"self":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/834","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=834"}],"version-history":[{"count":20,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/834\/revisions"}],"predecessor-version":[{"id":859,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/posts\/834\/revisions\/859"}],"wp:attachment":[{"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/media?parent=834"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/categories?post=834"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/labrigger.com\/blog\/wp-json\/wp\/v2\/tags?post=834"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}