Dental cement is also blue-sensitive. No sunburnt tongues, thanks!
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
The ebay laser, with the diffuser installed, sets up the Bondic in about a second. Without the diffuser, with a defocussed spot, it's instant.
But it's overkill. The blue LED that they supply works fine, without the headache.
I'm thinking adhesive lithography.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
comparing
I don't know what was meant by "The eye is very sensitive to pure colors." Our brain synthesises a "colour" out of the amounts of R, G & B sensation we get from pure colours. This works based on the breadth of wavelength sentitivity to the nominal colours. If our three cone cell types were narrowly tuned then when you looked at a rainbow it would appear to have three narrow colour strips. We would have no idea there was a broad spectrum!
Mike.
at a
ithin a
I meant what I said. You seem to understand how the eye works. What part of my statement was unclear?
-- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
If JL is looking at a laser with lotsa light, then there are these IR viewing cards. There are 700-1400 nm ones I've used... the laser tends to depopulate the phosphor so if you leave the card in one place the spot fads... Anyway then you could look at the spot with a CCD camera... kinda a convoluted idea.
George H.
Thor or somebody sells one with a UV LED recharging a spinning phosphor disc, so you can use them CW. Paulo could put something like that together in an afternoon. ;
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
part of my statement was unclear?
For instance, how would an eye detect a "pure colour"?
Mike.
The weak link there, is the webcam. Color sensing in such an item is done with three color filters, and it's NOT likely to be as easily analyzed for intensity as a simpler sensor (blue-enhanced silicon photodiode?).
The full light path (if your laser is a typical source) might require an integrating sphere. That's a spheric WHITE cavity, shine the laser in at aperture A and it illuminates aperture B (a slit) with uniform scattered light. With the slit, a lens, a rotating grating, and an exit slit (at the lens focus, in the path of the grating's first-order diffraction/reflection) completing the spectrum selection, then a photosensor behind the exit slit. Wide slits for high light throughput, narrow for fine spectral resolution.
It's useful to know that a blank CDR (of 650 MB) always has 1 hour of capacity, at 1 Hz rotation, i.e. 3600 'lines'. The grating will be slightly different if you use a 700 MB blank, and recorded CDs are somewhat noisy, so you'd prefer a section from a blank.
Rotating the grating with a stepper, that can be reversed for a second scan without losing sync, is the quick-n-dirty way to proceed, but you'll want a geared-down stepper because the total angle you want to swing is... maybe 30 degrees. You'll want to do two scans, the first with a reference.
It's easy to find ICs that implement visible-light sensing, but for careful work, a bolometer would be more accurate (and a chopper with AC measurement will improve sensor noise).
The eye would easily detect the color of a pure color. The eye can be fool ed by mixing pure colors. But give it a single wavelength like you get fro m an LED and it recognizes the color very well.
Heck, the eye can be fooled by multiple frequencies to the point of seeing colors that have no frequency in nature. Stimulate the blue and red recept ors with minimal stimulation of the green and you see red-violet which has no corresponding wavelength. But it shows up on the color wheel.
-- Rick C. -- Get 1,000 miles of free Supercharging -- Tesla referral code - https://ts.la/richard11209
Rick C wrote in news: snipped-for-privacy@googlegroups.com:
If you "see" it. it has a wavelength.
What is the wavelength of red-violet?
-- Rick C. -+ Get 1,000 miles of free Supercharging -+ Tesla referral code - https://ts.la/richard11209
Your original cornea is UV-opaque... in fact the cornea tends to fluoresce under certain long-wave UV frequencies.
Your replacement lens is UV-transparent.
I remember reading that during World War 2, the Allies actually sought out military personnel who had had corneas replaced, and assigned them to submarine duty off of the European coastline. They could see Morse code signals that were "blinked out" via UV-filtered lights by agents in (e.g.) France, while these signals were invisible to most people.
Might be mechanical eye-strain. Since the short-wave UV converges at a different distance from the cornea than visible light, your optical system is "fighting itself" - trying to focus two incompatible frequencies at the same time.
You might also be damaging your retina with too-short-wave UV exposure. There's probably a good reason that human corneas are UV-opaque. I would recommend wearing proper safety goggles when using that light.
Well, in that ballpark anyhow (supposedly it's 74 minutes not one hour, and the rotation is variable). According to Wikipedia, 1.6 microns line spacing and 20,633 lines total is a reasonable expectation.
Are you confusing cornea and lens???
-- Rick C. +- Get 1,000 miles of free Supercharging +- Tesla referral code - https://ts.la/richard11209
Sure...* Without his cornea John can be the one to align the UV led. :)
In grad school we had a UV lamp and grad students moving the phosphor around. co2 pumped vapor laser.. you'd fill the pump tube with organic vapor ('ant piss', formic acid for one.) and get that to lase. mostly in the FIR.
George H.
*I'll bet Paulo for an afternoon is more spendy than an ocean optics thing when all is said and done. (mostly because if he is good, then there are 10 other things you want him to do first.)Rick C wrote in news: snipped-for-privacy@googlegroups.com:
"red-violet" is ambiguous and not defined, but any light you see being guaranteed to have a wavelength is defined. So even your precious red-violet wiggles. You do know what a wiggle is, right?
Common sense much?
Exactly; it's just that I distinguish between "detect" and "is fooled"! I believe my TV generates no yellow light, but yet fools me into seeing yellow in its pictures, "pure" or otherwise...
Mike.
whit3rd wrote in news: snipped-for-privacy@googlegroups.com:
74 minutes. 2 channels. Red Book. 120mm disc. Original Sony spec. And then there are also subcodes.Growing to 86:30 on a disc stamped in 2019.
I knew it was pointless to respond to your idiotic question. So I guess I didn't display much common sense.
-- Rick C. ++ Get 1,000 miles of free Supercharging ++ Tesla referral code - https://ts.la/richard11209
at
fooled by mixing pure colors. But give it a single wavelength like you get from an LED and it recognizes the color very well.
ing colors that have no frequency in nature. Stimulate the blue and red re ceptors with minimal stimulation of the green and you see red-violet which has no corresponding wavelength. But it shows up on the color wheel.
Yes, and when it comes to pure colors, the eye can easily detect small diff erences in color.
-- Rick C. --- Get 1,000 miles of free Supercharging --- Tesla referral code - https://ts.la/richard11209
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