[Laser] Chucks question continued

[Chuck Hast]

Jim,
That did it. Now to go through it and get it into a stand alone little
piece of
say python code. A good exercise for me...

Then the larger angle was probably what was taking a bite out the numbers in
the original calculation using the formula that you indicated was doing the
approximation.


On Mon, May 14, 2018 at 8:21 PM, Jim Moss <n9jim-6 at pacbell.net> wrote:

> Chuck,
> It looks like we may have sin and tan issues here
>
> Original cited article:
> http://laserclassroom.com/products/measure-wavelength-laser-light/
>
> The angle based on your data is arctan(627/1000) = 32.08771207 Degrees
> That’s diffraction distance (X) / distance to target (L)
>
> The grating equation is WL = d sin(32.08771207), d=1000/mm
> Or 531.2 nM.  That matches your laser source.
>
> Note that in your original cited article approximates sin = tan.
> This is true when the angle is small, but introduces errors at larger
> angles.
>
> Here’s a calculator for the experiment: not using the approximation.
> http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/gratcal.html
>
> Jim
>
> Sent from my iPad
>
> > On May 14, 2018, at 5:40 PM, Jim Moss <n9jim-6 at pacbell.net> wrote:
> >
> > Chuck,
> >
> > After rereading, I think my statement on d is not correct. It may be as
> simple as 1 mm/1000. See link below to Newport.
> >
> > Could the error be related to that you are not reflecting directly off
> the grating surface? The experiment shows sending the beam thru the
> grating? If so, could there be an angle error induced?
> >
> > Could it be that the grating is facing the wrong way? Thus creating an
> offset due to the medium thickness of the grating material?
> >
> > Good summary on defraction gratings.
> > https://www.newport.com/t/grating-physics
> >
> > Jim
> >
> >
> > Sent from my iPad
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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