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 16:47:57 -0000 (UTC) Organization: A noiseless patient Spider Lines: 140 Message-ID: References: <1ghb7jt3882078r19n6jjgtirv25q27805@4ax.com> <36tg7jl5i74ui7rvmqhbg1jl9pldjehmvb@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Mon, 24 Jun 2024 18:47:57 +0200 (CEST) Injection-Info: dont-email.me; posting-host="9ffc810453e83f9a6df06f02ec5c0e5a"; logging-data="1090059"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19cY42VZ1ONk/94mc7A9N9t" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:oY5Bur2ul06cCIGxOFhOjklw9JY= sha1:wUirYt9puQj6aHZhqjFM/Rxd9TA= Bytes: 7039 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 -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics