strange blue laser optics

[Phil Hobbs]

On 2020-03-13 10:30, jlarkin@highlandsniptechnology.com wrote:

On Fri, 13 Mar 2020 05:34:49 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-12 19:02, John Larkin wrote:


I got a couple of these, to maybe cure UV-set epoxy.

https://www.ebay.com/itm/High-Power-Purple-405nm-Pointer-Burning-Light-Beam-Pen-with-Battery-Charger-USA/383162483108?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It came with a big lithium battery and a charger.

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

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.


I got a mild headache from just looking at the spot on the wall for
under a minute total. I also get a mild headache from using a UV
flashlight.

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

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.



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

 

[John Larkin]

On Fri, 13 Mar 2020 11:57:55 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-13 10:30, jlarkin@highlandsniptechnology.com wrote:
On Fri, 13 Mar 2020 05:34:49 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-12 19:02, John Larkin wrote:


I got a couple of these, to maybe cure UV-set epoxy.

https://www.ebay.com/itm/High-Power-Purple-405nm-Pointer-Burning-Light-Beam-Pen-with-Battery-Charger-USA/383162483108?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It came with a big lithium battery and a charger.

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

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.


I got a mild headache from just looking at the spot on the wall for
under a minute total. I also get a mild headache from using a UV
flashlight.

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

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.



Dental cement is also blue-sensitive. No sunburnt tongues, thanks!

Cheers

Phil Hobbs

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

 

[Mike Coon]

In article <000ab4b1-9c53-5d93-50ae-3757af8f2b7a@electrooptical.net>,
pcdhSpamMeSenseless@electrooptical.net says...

On 2020-03-13 06:42, TTman wrote:
On 13/03/2020 02:28, Rick C wrote:
On Thursday, March 12, 2020 at 8:59:37 PM UTC-4, John Larkin wrote:
If you only want an approximate number you can get that by
comparing
the color 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.  The eye is very sensitive to pure colors.

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.

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.

 

[Rick C]

On Friday, March 13, 2020 at 2:12:24 PM UTC-4, Mike Coon wrote:

In article <000ab4b1-9c53-5d93-50ae-3757af8f2b7a@electrooptical.net>,
pcdhSpamMeSenseless@electrooptical.net says...

On 2020-03-13 06:42, TTman wrote:
On 13/03/2020 02:28, Rick C wrote:
On Thursday, March 12, 2020 at 8:59:37 PM UTC-4, John Larkin wrote:
If you only want an approximate number you can get that by
comparing
the color 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.  The eye is very sensitive to pure colors.

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.

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!

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

 

[George Herold]

On Friday, March 13, 2020 at 11:56:24 AM UTC-4, Phil Hobbs wrote:

On 2020-03-13 10:37, jlarkin@highlandsniptechnology.com wrote:
On Fri, 13 Mar 2020 05:37:25 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-12 20:59, John Larkin wrote:
On Thu, 12 Mar 2020 16:54:46 -0700, John Robertson <spam@flippers.com
wrote:

On 2020/03/12 4:02 p.m., John Larkin wrote:


I got a couple of these, to maybe cure UV-set epoxy.

https://www.ebay.com/itm/High-Power-Purple-405nm-Pointer-Burning-Light-Beam-Pen-with-Battery-Charger-USA/383162483108?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It came with a big lithium battery and a charger.

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

I got a mild headache from just looking at the spot on the wall for
under a minute total. I also get a mild headache from using a UV
flashlight.



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.

https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/uv-protection/faq-20058021

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

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


John :-#(#


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.


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


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.



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.

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.

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

 

[whit3rd]

On Friday, March 13, 2020 at 7:37:49 AM UTC-7, jla...@highlandsniptechnology.com wrote:

On Fri, 13 Mar 2020 05:37:25 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-12 20:59, John Larkin wrote:

I wish I had a wideband spectrum analyzer, ideally something like 350
to 1700 nm.

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.)

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.

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).

 

[Mike Coon]

In article <8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye works. What
part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

Mike.

 

[Phil Hobbs]

On 2020-03-13 14:33, George Herold wrote:

On Friday, March 13, 2020 at 11:56:24 AM UTC-4, Phil Hobbs wrote:
On 2020-03-13 10:37, jlarkin@highlandsniptechnology.com wrote:
On Fri, 13 Mar 2020 05:37:25 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-12 20:59, John Larkin wrote:
On Thu, 12 Mar 2020 16:54:46 -0700, John Robertson <spam@flippers.com
wrote:

On 2020/03/12 4:02 p.m., John Larkin wrote:


I got a couple of these, to maybe cure UV-set epoxy.

https://www.ebay.com/itm/High-Power-Purple-405nm-Pointer-Burning-Light-Beam-Pen-with-Battery-Charger-USA/383162483108?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It came with a big lithium battery and a charger.

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

I got a mild headache from just looking at the spot on the wall for
under a minute total. I also get a mild headache from using a UV
flashlight.



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.

https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/uv-protection/faq-20058021

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

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


John :-#(#


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.


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


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.



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.


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

 

[whit3rd]

On Friday, March 13, 2020 at 12:44:01 PM UTC-7, whit3rd wrote:

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'.

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.

 

[Rick C]

On Friday, March 13, 2020 at 4:08:11 PM UTC-4, DecadentLinux...@decadence.org wrote:

Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:6da824f7-87cf-4ede-bfd0-fb71812c5801@googlegroups.com:

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon wrote:
In article
8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye works.
What

part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The eye
can be fooled by mixing pure colors. But give it a single
wavelength like you get from 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 receptors with minimal stimulation of the green and
you see red-violet which has no corresponding wavelength. But it
shows up on the color wheel.


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

 

[Rick C]

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon wrote:

In article <8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye works. What
part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The eye can be fooled by mixing pure colors. But give it a single wavelength like you get from 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 receptors 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 <gnuarm.deletethisbit@gmail.com> wrote in
news:6da824f7-87cf-4ede-bfd0-fb71812c5801@googlegroups.com:

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon wrote:
In article
8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye works.
What

part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The eye
can be fooled by mixing pure colors. But give it a single
wavelength like you get from 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 receptors with minimal stimulation of the green and
you see red-violet which has no corresponding wavelength. But it
shows up on the color wheel.

If you "see" it. it has a wavelength.

 

[Dave Platt]

In article <h7fl6fh0p9u8plsimnukodg22dq6a76656@4ax.com>,
John Larkin <xx@yy.com> wrote:

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

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.

I got a mild headache from just looking at the spot on the wall for
under a minute total. I also get a mild headache from using a UV
flashlight.

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.

 

[Rick C]

On Friday, March 13, 2020 at 4:34:32 PM UTC-4, Dave Platt wrote:

In article <h7fl6fh0p9u8plsimnukodg22dq6a76656@4ax.com>,
John Larkin <xx@yy.com> wrote:

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

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.

Are you confusing cornea and lens???

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[George Herold]

On Friday, March 13, 2020 at 2:57:27 PM UTC-4, Phil Hobbs wrote:

On 2020-03-13 14:33, George Herold wrote:
On Friday, March 13, 2020 at 11:56:24 AM UTC-4, Phil Hobbs wrote:
On 2020-03-13 10:37, jlarkin@highlandsniptechnology.com wrote:
On Fri, 13 Mar 2020 05:37:25 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-12 20:59, John Larkin wrote:
On Thu, 12 Mar 2020 16:54:46 -0700, John Robertson <spam@flippers.com
wrote:

On 2020/03/12 4:02 p.m., John Larkin wrote:


I got a couple of these, to maybe cure UV-set epoxy.

https://www.ebay.com/itm/High-Power-Purple-405nm-Pointer-Burning-Light-Beam-Pen-with-Battery-Charger-USA/383162483108?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It came with a big lithium battery and a charger.

Two weird things:

If I shoot it at a white wall, I can see the spot with my right eye,
but not with my left one. The right eye has had cataract lens
replacement.

I got a mild headache from just looking at the spot on the wall for
under a minute total. I also get a mild headache from using a UV
flashlight.



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.

https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/uv-protection/faq-20058021

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

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


John :-#(#


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.


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


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.



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.


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. ;

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.)

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

 

Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:1f1a6ad4-4c4f-43a4-8a7e-8357e3fed14b@googlegroups.com:

On Friday, March 13, 2020 at 4:08:11 PM UTC-4,
DecadentLinux...@decadence.org wrote:
Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:6da824f7-87cf-4ede-bfd0-fb71812c5801@googlegroups.com:

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon wrote:
In article
8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye
works.
What

part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The eye
can be fooled by mixing pure colors. But give it a single
wavelength like you get from 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 receptors with minimal stimulation
of the green and you see red-violet which has no corresponding
wavelength. But it shows up on the color wheel.


If you "see" it. it has a wavelength.

What is the wavelength of red-violet?

"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?

 

[Mike Coon]

In article <6da824f7-87cf-4ede-bfd0-fb71812c5801@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon wrote:
In article <8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye works. What
part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The eye can be fooled by mixing pure colors. But give it a single wavelength like you get from 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 receptors with minimal stimulation of the green and you see red-violet which has no corresponding wavelength. But it shows up on the color wheel.

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.

 

Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:b34b0e9f-ceb7-4cba-b09e-f6291a667968@googlegroups.com:

On Friday, March 13, 2020 at 7:37:05 PM UTC-4,
DecadentLinux...@decadence.org wrote:
Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:1f1a6ad4-4c4f-43a4-8a7e-8357e3fed14b@googlegroups.com:

On Friday, March 13, 2020 at 4:08:11 PM UTC-4,
DecadentLinux...@decadence.org wrote:
Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:6da824f7-87cf-4ede-bfd0-fb71812c5801@googlegroups.com:

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon
wrote:
In article
8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye
works.
What

part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The
eye can be fooled by mixing pure colors. But give it a
single wavelength like you get from 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 receptors with minimal
stimulation of the green and you see red-violet which has no
corresponding wavelength. But it shows up on the color
wheel.


If you "see" it. it has a wavelength.

What is the wavelength of red-violet?


"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?

I knew it was pointless to respond to your idiotic question. So I
guess I didn't display much common sense.

Visible light has wavelengths. Do you deny this?

Trying to say that two streams combined to make your 'color' go
together, but their wavelength disappears into the void?

The spectrum the prism puts up includes your "red-violet".

That entire gamut is full of light and each separation thereof has
a wavelength.

Oh and "you knew it was pointless..." Look jackass... You made no
point. You explained NOTHING about your claim.

So YOU, motherfucker, are the idiotic one. Yeah, somebody got
fooled alright. But it wasn't your eyes.

 

[Rick C]

On Friday, March 13, 2020 at 7:37:05 PM UTC-4, DecadentLinux...@decadence.org wrote:

Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:1f1a6ad4-4c4f-43a4-8a7e-8357e3fed14b@googlegroups.com:

On Friday, March 13, 2020 at 4:08:11 PM UTC-4,
DecadentLinux...@decadence.org wrote:
Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:6da824f7-87cf-4ede-bfd0-fb71812c5801@googlegroups.com:

On Friday, March 13, 2020 at 3:23:16 PM UTC-4, Mike Coon wrote:
In article
8c62ca85-cb3a-4023-b98e-6a12606506ae@googlegroups.com>,
gnuarm.deletethisbit@gmail.com says...

I meant what I said. You seem to understand how the eye
works.
What

part of my statement was unclear?

For instance, how would an eye detect a "pure colour"?

The eye would easily detect the color of a pure color. The eye
can be fooled by mixing pure colors. But give it a single
wavelength like you get from 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 receptors with minimal stimulation
of the green and you see red-violet which has no corresponding
wavelength. But it shows up on the color wheel.


If you "see" it. it has a wavelength.

What is the wavelength of red-violet?


"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?

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

 

whit3rd <whit3rd@gmail.com> wrote in
news:95a82b99-63b9-4c2d-a234-5545ac0aef77@googlegroups.com:

On Friday, March 13, 2020 at 12:44:01 PM UTC-7, whit3rd wrote:

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'.

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.

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.