Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Phil Hobbs Newsgroups: sci.electronics.design Subject: Re: how the laser happened Date: Mon, 24 Jun 2024 23:02:53 -0000 (UTC) Organization: A noiseless patient Spider Lines: 157 Message-ID: References: <1ghb7jt3882078r19n6jjgtirv25q27805@4ax.com> <36tg7jl5i74ui7rvmqhbg1jl9pldjehmvb@4ax.com> <6kkj7jtvseqiu1iq3i4tl79ge6vl67n971@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Tue, 25 Jun 2024 01:02:54 +0200 (CEST) Injection-Info: dont-email.me; posting-host="85f304439f23d09303e0a6f482b45e27"; logging-data="1236658"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/BMeaZ1y8/gyBLE7zXKyYO" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:ECRSFh4XJrqe5DVtN5AdfE4XpT4= sha1:2aqxk4ijTD1+OeS017GMsz9AY/0= Bytes: 7844 john larkin wrote: > On Mon, 24 Jun 2024 16:47:57 -0000 (UTC), Phil Hobbs > wrote: > >> john larkin wrote: >>> On Mon, 24 Jun 2024 00:22:06 -0000 (UTC), Phil Hobbs >>> wrote: >>> >>>> john larkin wrote: >>>>> On Sun, 23 Jun 2024 22:09:42 -0000 (UTC), Phil Hobbs >>>>> wrote: >>>>> >>>>>> john larkin wrote: >>>>>>> On Sun, 23 Jun 2024 18:08:52 -0000 (UTC), Phil Hobbs >>>>>>> wrote: >>>>>>> >>>>>>>> john larkin wrote: >>>>>>>>> On Sun, 23 Jun 2024 16:39:56 -0000 (UTC), Cursitor Doom >>>>>>>>> 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 wrote in >>>>>>>>>>> : >>>>>>>>>>> >>>>>>>>>>>> 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 wrote in >>>>>>>>>>>>> <1ghb7jt3882078r19n6jjgtirv25q27805@4ax.com>: >>>>>>>>>>>>> >>>>>>>>>>>>>> On Fri, 21 Jun 2024 17:56:36 +0100, Cursitor Doom >>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Fri, 21 Jun 2024 06:05:21 -0700, john larkin >>>>>>>>>>>>>>> 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