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From: john larkin <jl@650pot.com>
Newsgroups: sci.electronics.design
Subject: Re: how the laser happened
Date: Mon, 24 Jun 2024 13:13:29 -0700
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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?

Why wouldn't they?