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Right now, you can get opaque black plastic glasses with an array of pinholes. These work to correct a variety of focusing problems, since pinhole cameras have
by jcl 16y ago
Right now, you can get opaque black plastic glasses with an array of pinholes. These work to correct a variety of focusing problems, since pinhole cameras have an infinite depth of field. The drawback is that pinholes let in very little light, so although the image is in focus, it is very dim. And, of course, the image between the pinholes is not as good as it is near the pinholes.
http://en.wikipedia.org/wiki/Pinhole_glasses http://en.wikipedia.org/wiki/Pinhole_glasses
It sounds like this new product has a similar set of advantages and drawbacks, and maybe even works in a similar fashion.
- davisp 16y agoI don't have access to the full text article so I can't say for certain but the article makes it sound like the effect is accomplished in a fashion similar to phase contrast microscopy. http://en.wikipedia.org/wiki/Phase_contrast_microscopy http://en.wikipedia.org/wiki/Phase_contrast_microscopy The basic concept of phase contrast is that certain objects (notably, monolayers of biological specimens) don't greatly affect the amplitude of light passing through them. IOW, viewed under "normal" optics, they would appear transparent. On the other hand it was noticed that these objects do cause the phase of light to shift as it passes through the specimens. The basic idea is that you create a system that has light passing through the specimen in two paths. The major light path is dimmed and accelerated by half a wavelength. This gives us a situation of theoretically perfect destructive interference at the point of observation. When the reference light waves pass through a phase object, it changes the phase of the light and introduces perturbances to the completely destructive interference which results in an observable image of the specimen. The reason these glasses remind me of phase contrast is the concentric circles milled to specific depths and widths (which is one of two important pieces of a phase contrast microscope, the objective). Also, the article describes the effects based in terms of phase: The rings shift the phase of the light waves passing through the lens, leading to patterns of both constructive and destructive interference. Using a computer model to calculate how changes in the diameter and position of the rings alter the pattern, Zalevsky came up with a design that creates a channel of constructive interference perpendicular to the lens through each of the 25 structures. Within these channels, light from both near and distant objects is in perfect focus. I never took the optics courses in school so I'm not able to connect how the phase properties are leveraged for focus. The only thing that comes to mind is that they're using phase differences to selectively destruct out of focus rays and reinforcing in focus rays (hand wavy factor: 8.6 of 10). [ed: speling]
- metamemetics 16y agoElementary yet interesting. I just "constructed" a pinhole by curling my index finger in my thumb, and could read letters on this page. At the same range without wearing contacts or glasses, I am unable to separate words. Only lines of text. I use glasses in the evening and contacts in the morning, so the dimming could perhaps be beneficial for circadian rhythms if I need to use a computer, although I recognize that probably has more to do with the spectrum of light than the intensity.