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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 00:22:06 -0000 (UTC)
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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. 
> 
> Nature seems to use any effect that's not flat impossible, whether
> biologists approve or not.
> 
> 
> 
> 



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