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 00:22:06 -0000 (UTC) Organization: A noiseless patient Spider Lines: 135 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 02:22:06 +0200 (CEST) Injection-Info: dont-email.me; posting-host="cfde3d329535d6b6e1b4ba9cc7a3e5de"; logging-data="623507"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/KIGdIAQoMXwONMGPz0aaM" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:wysrwkAqI6AA6Em3/qf6YA8FiOc= sha1:QSfNXIkytfR8vKKv1L3orMt8lhI= Bytes: 6573 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. > > 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