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From: john larkin <jlarkin_highland_tech>
Newsgroups: sci.electronics.design
Subject: Re: Instead scopes
Date: Sat, 31 Aug 2024 16:40:45 -0700
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On Sat, 31 Aug 2024 20:14:35 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>john larkin <jl@650pot.com> wrote:
>> On Sat, 31 Aug 2024 17:59:04 -0000 (UTC), Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>> 
>>> john larkin <jlarkin_highland_tech> wrote:
>>>> On Thu, 29 Aug 2024 21:50:19 +0100, liz@poppyrecords.invalid.invalid
>>>> (Liz Tuddenham) wrote:
>>>> 
>>>>> john larkin <jl@650pot.com> wrote:
>>>>> 
>>>>>> On Thu, 29 Aug 2024 16:15:59 GMT, Jan Panteltje <alien@comet.invalid>
>>>>>> wrote:
>>>>>> [...]
>>>>>>> Calculators yes.
>>>>> 
>>>>>> We weren't alowed to use a calculator on exams because it would give
>>>>>> an unfair advantage to the students that could afford one.
>>>>> 
>>>>> We were allowed mechanical calculators (Facits etc.) but there were only
>>>>> enough for half the candidates.  Half of us were locked in a room with a
>>>>> spare envigilator acting as a guard while the other half sat the exam
>>>>> then we swapped places and the ones who had taken the exam were locked
>>>>> in while the second group sat the exam.
>>>>> 
>>>>> Electronic calculators did not exist, but we did learn to program an
>>>>> analogue computer where 100v = 1 Machine Unit.
>>>> 
>>>> A lot of current engineering practise is left over from the days when
>>>> computing was expensive or non-existant. Things like s-parameters and
>>>> Smith charts.
>>> 
>>> I?ve done a lot of lowish-power RF stuff, and mostly agree with you about
>>> the practicality of using S parameters in hand calculations. 
>>> 
>>> However, I cordially disagree with your sentiments regarding Smith charts. 
>>> 
>>> For one thing, they?re super useful for designing optical coatings, but
>>> that?s a minority interest on SED. 
>>> 
>>> In RF work one runs into a lot of matching jobs involving modulated sine
>>> waves. 
>>> 
>>> One typical example from my work is coupling sine modulation into a diode
>>> laser, for modulation-generated carrier interferometry.  (*)
>>> 
>>> A Smith chart makes it super easy to try out different schemes, such as
>>> series/shunt stubs, lumped elements, or any combination thereof. 
>>> 
>>> Useless for bandwidths of an octave or more, and so apt to be undervalued
>>> by crass time-domain types. ;)
>> 
>> The interesting parts of the world are wideband and nonlinear. So are
>> we.
>
>I noticed. ;)
>
>> 
>> Sine waves are BORING.
>
>You’ve been hanging out with the wrong crowd, obviously.  Tsk tsk. 
>
>Cheers 
>
>Phil Hobbs 
>> 
>> 

There is a story about Feynman. Somebody bumped into him in a hallway
and suggested using multilayer mirrors. He came back two days later
with the complete theory of multilayer optical filters.

ASML uses zillion-layer mirrors in their EUV systems, at 13 nm.