[Laser] last message was 8/12/2016?

Chuck Hast wchast at gmail.com
Mon May 14 19:30:15 EDT 2018 

That did it. I went back through and all of the indications I had on
different
documents do a calculation to figure out the distance between lines but the
lines are ZERO width, now that I look at it. That cannot be, or I am missing
something.

Take a look at the UCLA video here, I do not see where he takes into account
line width just spacing from center of line to center of line.

https://www.youtube.com/watch?v=E-3uht9LAhM

Several others have given the same calculation, I end up at the same thing
Spacing = 1 um, so the line is infinitely small based on that. Of course we
know
it is not.


On Mon, May 14, 2018 at 5:07 PM, Chuck Hast <wchast at gmail.com> wrote:

> Jim
> Oops, yes at 1 um the line would not exist, I was following another
> calculation
> on the spacing and somehow I did not see where the line width was, the
> forumla
> gave me 1 um, also gives 3.33 um for the 300 line grate, I had better go
> back
> and check that.
>
> Thank you,
>
>
> On Mon, May 14, 2018 at 11:21 AM, Jim Moss <n9jim-6 at pacbell.net> wrote:
>
>> Chuck,
>> d is the slit width, this is not the same as lines/mm. It is the space
>> between the lines.  The line as are m
>> Not zero width.
>> So d will be < 1um.
>> Since the other parameters are known... d must be 0.848 um
>>
>> Jim
>>
>> Sent from my iPad
>>
>> > On May 13, 2018, at 4:39 PM, Chuck Hast <wchast at gmail.com> wrote:
>> >
>> > Jim,
>> > here are my parameters
>> > Laser is a DPSS 532nm (using it as a reference as this DPSS is always
>> 532nm)
>> >
>> > I am using this document as my formula source. I have gone at it using
>> trig
>> > too and it still comes out wrong.
>> >
>> > http://laserclassroom.com/products/measure-wavelength-laser-light/
>> >
>> > L= Distance grating to the screen with the meter stick on it  =  1000mm
>> > d = line spacing on grating @ 1000/mm = 1/micron
>> > N = Maxima N0 = Maxima #0, N1 = Maxima #1
>> > X = Distance N0 to N1 = 627mm
>> > λ = 532nm
>> >
>> > The formula I am using is as follows:
>> > λ= (X)(d)/L  λ= (627)(0.001)/1000  λ=0.000627 mm or 627 nm which is NOT
>> > 532 nm. Either my data is bad OR the line count is bad. I have 10 of
>> these
>> > grating slides (it was cheaper to buy the pack than one) and all of them
>> > give
>> > the same error.  Just for grins I tried 3 different DPSS lasers and of
>> > course
>> > all of them gave the same number.
>> >
>> >
>> >> On Sun, May 13, 2018 at 10:34 AM, Jim Moss <n9jim-6 at pacbell.net>
>> wrote:
>> >>
>> >> Chuck,
>> >>
>> >> I remember using the cd as grating experiments.
>> >>
>> >> Sin(x) = wavelength / gratings
>> >> X is diffraction angle
>> >>
>> >> Increasing the grating from 300 to 1000 decreases sin(x) by 3.3x.
>> >> X also decreases.
>> >>
>> >> For the measurement device you read the diffraction offset and
>> distance to
>> >> the target
>> >>
>> >> Accuracy depends on a few variables.
>> >> Increasing the grating density will decrease the angle.
>> >> If you kept the same target distance, this increases the sensitivity of
>> >> measuring the offset.
>> >>
>> >> I’m not sure what you did to decrease the spot size in your instrument,
>> >> but that also can add error.
>> >>
>> >> See this for a short description.
>> >> http://www.nnin.org/sites/default/files/files/Karen_rama_TG_
>> part2_0.pdf
>> >>
>> >> Jim
>> >>
>> >>
>> >>
>> >>
>> >> Sent from my iPad
>> >>
>> >>> On May 12, 2018, at 4:47 PM, Chuck Hast <wchast at gmail.com> wrote:
>> >>>
>> >>> Nuu, no paper, just a question. I am building a spectrograph to
>> measure
>> >> the
>> >>> wavelength of lasers I am incorporating into some tools.
>> >>>
>> >>> Some years back I built one to determine the wavelength of lasers I
>> was
>> >>> using
>> >>> in glass container inspectors. The thing was spot on, I checked the
>> >> device
>> >>> using a DPSS laser at 532nm, and a HeNe at 632.8nm. In both cases it
>> was
>> >>> well within 5nm of what it should have been.
>> >>>
>> >>> I have built one just recently, but I am not getting anywhere near the
>> >>> precision
>> >>> I was getting with the one back then. I have tested it with one of the
>> >> DPSS
>> >>> lasers I used on the original one. I do not have a HeNe here at this
>> >> moment
>> >>> so not sure where the red end is.
>> >>>
>> >>> The  original used a grate at 300 L/mm, figuring on greater accuracy I
>> >>> bought
>> >>> the 1000 L/mm grate.
>> >>>
>> >>> The series of test I have done have given me about 548nm for a 532nm
>> DPSS
>> >>> laser, that is way off. The only real difference between the original
>> >>> instrument
>> >>> and this one is the grating is 1000 L/mm, the original was 300 L/mm.
>> The
>> >>> only
>> >>> thing that I can suspect is the 1000 L/mm is NOT 1000 L/mm but
>> something
>> >>> more. I guess I will have to reverse the calculations and see if I can
>> >>> determine
>> >>> the real number of lines/mm.
>> >>>
>> >>> I may also buy a 300 L/mm grate, then I will have it all the same as
>> the
>> >>> original.
>> >>>
>> >>>
>> >>> Wonder if anyone else has run into this sort of thing.
>> >>>
>> >>>
>> >>>
>> >>> On Sat, May 12, 2018 at 11:01 AM, John McNulty <
>> john at generalrobots.com>
>> >>> wrote:
>> >>>
>> >>>> Greetings All,
>> >>>>
>> >>>> Perhaps there’s a learned paper title forthcoming?
>> >>>>
>> >>>> "Loop-back Latency in Laser Links" ;-)
>> >>>>
>> >>>> Best Wishes to All,
>> >>>>
>> >>>> J McN
>> >>>>
>> >>>>> On 12 May 2018, at 15:48, Glenn Thomas <glennt at gbis.com> wrote:
>> >>>>>
>> >>>>> FWIW, the last message I had on this group was August 12, 2016...
>> >>>>>
>> >>>>>> On 5/12/2018 7:33 AM, Zack Widup wrote:
>> >>>>>> I'm still here. Haven't seen any activity on this group in ages. Go
>> >>>> ahead
>> >>>>>> with your question!
>> >>>>>>
>> >>>>>> 73, Zack W9SZ
>> >>>>>>
>> >>>>>>
>> >>>>>
>> >>>>> --
>> >>>>> "i" before "e" except after "c", or when sounded as "a" as in
>> neighbor
>> >>>> and weigh.
>> >>>>>
>> >>>>> This rule is “counterfeit”. General spelling rules “forfeit”
>> >> generality.
>> >>>>> They are “foreign”, being not “either” or “neither”, possibly the
>> >> result
>> >>>> of some
>> >>>>> “leisure” activity of a “sovereign heir” who, lacking “height”, is
>> >>>> studying,
>> >>>>> without “conscience, inefficient glacier science”. It’s not as
>> >>>> nutritious
>> >>>>> as "protein". It's just plain old "weird"
>> >>>>>
>> >>>>> Is this example “sufficient”?
>> >>>>>
>> >>>>>
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>> >>>
>> >>>
>> >>> --
>> >>>
>> >>> Chuck Hast  -- KP4DJT --
>> >>> I can do all things through Christ which strengtheneth me.
>> >>> Ph 4:13 KJV
>> >>> Todo lo puedo en Cristo que me fortalece.
>> >>> Fil 4:13 RVR1960
>> >>> ______________________________________________________________
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>> >
>> >
>> >
>> > --
>> >
>> > Chuck Hast  -- KP4DJT --
>> > I can do all things through Christ which strengtheneth me.
>> > Ph 4:13 KJV
>> > Todo lo puedo en Cristo que me fortalece.
>> > Fil 4:13 RVR1960
>> > ______________________________________________________________
>> > Laser mailing list
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>>
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>
>
>
> --
>
> Chuck Hast  -- KP4DJT --
> I can do all things through Christ which strengtheneth me.
> Ph 4:13 KJV
> Todo lo puedo en Cristo que me fortalece.
> Fil 4:13 RVR1960
>
>


-- 

Chuck Hast  -- KP4DJT --
I can do all things through Christ which strengtheneth me.
Ph 4:13 KJV
Todo lo puedo en Cristo que me fortalece.
Fil 4:13 RVR1960

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