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

Sun May 13 19:39:24 EDT 2018

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