strange blue laser optics

fredag den 13. marts 2020 kl. 00.02.22 UTC+1 skrev John Larkin:

My eye doctor, a really cool guy, blasted my right eye with his old CW argon ion laser, to spot-weld my retina to the back of my eyeball. That kinda hurt. He's Thai and his first and last names are both about

He also removed a secondary cataract by cutting a hole in the rear of my lens capsule with a pulsed yag.

The blue "burning" laser makes a very hot spot if you focus it carefully.

I 'like' the description "High quality and perfect design." where have we heard 'perfect' before? And why should you trust them?

I'm very suspicious of any and all unregulated products from China. They claim it is 405nm, but unless you have a spectrum analyzer you have no idea if it is also emitting UV-B or other dangerous UV radiation. Perhaps you could lend one to Winfield - I imagine he has one of those S.A.s rattling around his shop!

Wear proper UV safety glasses (at a minimum UV-A/B rated sun glasses) when using this.

I'd treat it like light from an arc-welder, dangerous until proven otherwise.

John :-#(#

Well, toothpicks are dangerous too, if you poke one in your eye.

It seems to work. The spot, well focussed, feels very hot on my hand, so it's a lot of power. It came with a spot-matrix-pattern diffuser installed, which might be prudent to leave in place for curing epoxy. Amazing for under $10.

I wish I had a wideband spectrum analyzer, ideally something like 350 to 1700 nm. All the available OSAs go for extreme resolution over a narrow range, well under an octave. I just want to know about what the wavelength of a laser or LED is.

John Robertson wrote in news: snipped-for-privacy@giganews.com:

Because they are such 'great businessmen'.

Finished at the top of their class...

All work is performed by stable geniuses. But all the facts about how they operate are 'classified'.

Available as in available at your shop? Otherwise, there are quite a few good (but $$$) options, e.g.

? David

If you only want an approximate number you can get that by comparing the co lor by eye. Look at the laser spot on white paper, look at a known LED on the same white paper. You should be able to get within a few 10s of nm. T he eye is very sensitive to pure colors.

A CD or DVD disk does not help?

Some artificial lenses are transparnt to UV, your original lens is not.

Possilby your visual cortex stressed by the significantly different inputs.

There was a Car Talk puzzler many years ago that hinged on that--optical signalling to the French resistance using UV filters that made the flashes visible to old men (who had had cataracts removed) but not to young German soldiers.

UV epoxy is usually designed for Hg I-line (365-nm) peak sensitivity. I generally use a 380-nm LED, which works fine. How well does your 405 work?

CHeers

Phil Hobbs

You can do that with a CD and a ruler, with an IR viewer for the longer wavelengths. (I have a somewhat-broken lead salt vidicon camera that used to go out to 2.2 um.)

Cheers

Phil Hobbs

Unless you're colour blind..... Not so easy !

And even with normal vision, that kind of resolution is only available between 450 and 600 nm at best.

Cheers

Phil Hobbs

Bondic comes with a fairly wimpy blue LED, and it sets the stuff up hard in seconds. Clear through vias to the bottom of the board.

I haven't tried my super laser on Bondic. I'll do that today.

Or unless you are wondering if a laser is 850, 1310, or 1550 nm.

So it wouldn't be difficult to design a small wide-range, low resolution spectrometer, with some cheap gratings, an IR sensitive webcam, and a little software.

Sure does at 450nm!

We are buying a bunch of custom machined extrusions from China, as small instrument boxes. We will locally blue anodize them and their custom end plates, to keep the colors uniform. Then we plan to add the artwork by blasting off the anodize with a CO2 laser.

I think the n/c laser will cost around $3K or so.

Right, provided you always start with a collimated beam. "IR-sensitive webcam" is the hard part. An Electrophysics 7290A from eBay and a USB frame grabber would be the ticket for that.

Cheers

Phil Hobbs