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From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Newsgroups: sci.electronics.design
Subject: Re: how the laser happened
Date: Mon, 24 Jun 2024 23:02:53 -0000 (UTC)
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john larkin <jl@650pot.com> wrote:
> On Mon, 24 Jun 2024 16:47:57 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
> 
>> john larkin <jl@650pot.com> wrote:
>>> On Mon, 24 Jun 2024 00:22:06 -0000 (UTC), Phil Hobbs
>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>> 
>>>> john larkin <jl@650pot.com> wrote:
>>>>> On Sun, 23 Jun 2024 22:09:42 -0000 (UTC), Phil Hobbs
>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>> 
>>>>>> john larkin <jl@650pot.com> wrote:
>>>>>>> On Sun, 23 Jun 2024 18:08:52 -0000 (UTC), Phil Hobbs
>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>>>> 
>>>>>>>> john larkin <jl@650pot.com> wrote:
>>>>>>>>> On Sun, 23 Jun 2024 16:39:56 -0000 (UTC), Cursitor Doom
>>>>>>>>> <cd999666@notformail.com> wrote:
>>>>>>>>> 
>>>>>>>>>> On Sun, 23 Jun 2024 05:03:34 GMT, Jan Panteltje wrote:
>>>>>>>>>> 
>>>>>>>>>>> On a sunny day (Sat, 22 Jun 2024 17:23:40 -0000 (UTC)) it happened
>>>>>>>>>>> Cursitor Doom <cd999666@notformail.com> wrote in
>>>>>>>>>>> <v571as$3rs0j$2@dont-email.me>:
>>>>>>>>>>> 
>>>>>>>>>>>> On Sat, 22 Jun 2024 06:19:49 GMT, Jan Panteltje wrote:
>>>>>>>>>>>> 
>>>>>>>>>>>>> On a sunny day (Fri, 21 Jun 2024 11:32:56 -0700) it happened john
>>>>>>>>>>>>> larkin <jl@650pot.com> wrote in
>>>>>>>>>>>>> <1ghb7jt3882078r19n6jjgtirv25q27805@4ax.com>:
>>>>>>>>>>>>> 
>>>>>>>>>>>>>> On Fri, 21 Jun 2024 17:56:36 +0100, Cursitor Doom <cd@notformail.com>
>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> On Fri, 21 Jun 2024 06:05:21 -0700, john larkin <jl@650pot.com>
>>>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> There was a thread somewhere above about photon wave/particle
>>>>>>>>>>>>>>>> duality.
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> This is worth reading:
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> https://www.amazon.com/How-Laser-Happened-Adventures-Scientist/dp/
>>>>>>>>>>>> 0195153766
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> Einstein, in one of his fits of genius, predicted in around 1916
>>>>>>>>>>>>>>>> that under the right conditions, a photon could pass by an excited
>>>>>>>>>>>>>>>> atom and the atom would kick in another photon, or add to the wave
>>>>>>>>>>>>>>>> amplitude, depending on how you feel about these things. He called
>>>>>>>>>>>>>>>> it stimulated emission. He also declared that the laws of
>>>>>>>>>>>>>>>> thermodynamics made this effect impossible to use in practical
>>>>>>>>>>>>>>>> situations.
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> In 1951, Charles Townes invented a work-around trick and built the
>>>>>>>>>>>>>>>> maser, a gaseous microwave oscillator. His superiors thought he was
>>>>>>>>>>>>>>>> crazy to dispute Einstein and almost threw him out of grad school,
>>>>>>>>>>>>>>>> but it worked.
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> In 1960, Theodore Maiman at HRL made the first ruby laser, and Bell
>>>>>>>>>>>>>>>> Labs soonafter made a HeNe.
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> What's interesting is that any decent neon sign shop could have
>>>>>>>>>>>>>>>> built a HeNe laser in 1920.
>>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>>> HRL sounds like a very cool place, up in the hills above Malibu.
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> Wasn't that where Jane Mansfield used to go out bathing?
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>> Keep your mind on electronics, young man.
>>>>>>>>>>>>>> 
>>>>>>>>>>>>>> The Getty Museum is in Malibu. Go there if you can. Hearst Castle,
>>>>>>>>>>>>>> too,
>>>>>>>>>>>>>> up the road a bit.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> I've been to Malibu, even did some work there...
>>>>>>>>>>>>> Did not go to any museum, but did go to the beach.
>>>>>>>>>>>> 
>>>>>>>>>>>> Did you see Jane? What about lobsters? Any lobsters around? 
>>>>>>>>>>> 
>>>>>>>>>>> Na, but some other beatiful women I met.
>>>>>>>>>>> Last time we went looking for edible seaweed ...
>>>>>>>>>> 
>>>>>>>>>> Argh! Never mind. I believe Jane had terrible problems with lobsters when 
>>>>>>>>>> she went out bathing in Malibu. But you don't know anything about that, 
>>>>>>>>>> clearly. It obviously wasn't publicised in Holland.
>>>>>>>>> 
>>>>>>>>> This thread is about lasers, not lobsters. 
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>> 
>>>>>>>> Well, Schawlow famously said, ?Anything will lase, if you hit it hard
>>>>>>>> enough.?
>>>>>>>> 
>>>>>>>> I expect that includes lobsters. 
>>>>>>>> 
>>>>>>>> Cheers 
>>>>>>>> 
>>>>>>>> Phil Hobbs 
>>>>>>> 
>>>>>>> But no, seriously, there must be some laser action, or at least some
>>>>>>> sort of stimulated emission, some sort of super-fluorescence, in
>>>>>>> nature somewhere. 
>>>>>> 
>>>>>> Sure. Cosmic masers occur in interstellar giant molecular clouds, for
>>>>>> instance. 
>>>>>> 
>>>>>> The lifetime of suitable upper states drops steeply with increasing energy,
>>>>>> which means that visible laser action requires much stronger pumping. 
>>>>>> 
>>>>>> While that can in principle happen naturally, it would be in places with a
>>>>>> lot of other stuff going on, so it would be less noticeable. 
>>>>>> 
>>>>>> You don?t have resonators in interstellar space, so it wouldn?t be highly
>>>>>> directional. 
>>>>>> 
>>>>>> Cheers 
>>>>>> 
>>>>>> Phil Hobbs 
>>>>> 
>>>>> I was thinking about a biological laser too.
>>>>> 
>>>>> I could imagine an eyeball with some sort of stimulated emission
>>>>> effect, in the vitreus humor or in the retina, to improve night
>>>>> vision, basically a photon amplifier.
>>>> 
>>>> Difficult. For a start, you need a pump source of high intensity and
>>>> narrowish bandwidth, and there are no biological examples that I know of. 
>>> 
>>> There are chemical lasers.
>>> 
>>> 
>> 
>> And nuclear ones!
>> 
>> Cheers 
>> 
>> Phil “certified laser jock” Hobbs 
> 
> Living things can certainly pump up molecular energy states to make
> visible light. Why couldn't they produce the population inversions
> that enable stimulated emission and optical gain?

Because bioluminescence doesn’t get anywhere near the pumping rate required
for a visible laser. 

> Why wouldn't they?
That’s more of a theological question. ;)

Cheers 

Phil Hobbs 
-- 
Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /
Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics