{"id":13236,"date":"2013-09-23T21:31:34","date_gmt":"2013-09-24T02:31:34","guid":{"rendered":"http:\/\/blog.kenperlin.com\/?p=13236"},"modified":"2013-09-23T21:31:34","modified_gmt":"2013-09-24T02:31:34","slug":"pure-green","status":"publish","type":"post","link":"https:\/\/blog.kenperlin.com\/?p=13236","title":{"rendered":"Pure green"},"content":{"rendered":"

The second of my interactive diagrams from yesterday<\/a> showed how the three types of color receptors in the human eye respond to different wavelengths of light. These three kinds of cone-shaped cells detect, respectively, short, medium and long wavelengths, and so they are called S-cones, M-cones and L-cones.<\/p>\n

One look at the diagram and it’s clear that light is never detected only by M-cones. What we think of as green light actually triggers both M-cones and L-cones. It just triggers the M-cones a little more strongly.<\/p>\n

So of course I started to wonder what it would look like if only your M-cones were triggered. This would be a kind of “pure green” light that no human being has ever seen. Would it look like a completely new color?<\/p>\n

The only way I can think of to do this would be to shine a very finely patterned light at your eye, with bright dots placed exactly where the M-cones are, but avoiding the L-cones.<\/p>\n

To make this work you would need a high speed eye tracker that measures the slight movements of the eye, and continually moves the pattern of dots to match this movement. This would ensure that each dot illuminates only an M-cone, not an L-cone.<\/p>\n

But how small do the dots need to be? Well, one degree of visual angle is about 0.3mm on your retina. And each M-cone near the center of the retina is about 1um across, which means you’d need a dot that subtended about 1\/300 of a degree in visual angle.<\/p>\n

The biggest problem I can foresee is that people can’t easily focus an image to such fine detail. To get around this problem, the first thing I would try is to use a laser to send the image into the eye through the center of the pupil, where the eye’s lens has little effect on depth of focus.<\/p>\n

It would take a lot of engineering to get this all working. On the other hand, it would be cool to see a new color that nobody has ever seen before.<\/p>\n","protected":false},"excerpt":{"rendered":"

The second of my interactive diagrams from yesterday showed how the three types of color receptors in the human eye respond to different wavelengths of light. These three kinds of cone-shaped cells detect, respectively, short, medium and long wavelengths, and so they are called S-cones, M-cones and L-cones. One look at the diagram and it’s … Continue reading “Pure green”<\/span><\/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":[],"_links":{"self":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/13236"}],"collection":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13236"}],"version-history":[{"count":9,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/13236\/revisions"}],"predecessor-version":[{"id":13245,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/13236\/revisions\/13245"}],"wp:attachment":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13236"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}