[Laser] Chucks question continued

[Jim Moss]

Mike found a spectrometer on eBay. 
New they are about $150, and there is a $70 model as well. From a French company Thunder Optics.
Jim

Sent from my iPhone

> On May 14, 2018, at 9:44 PM, Chuck Hast <wchast at gmail.com> wrote:
> 
> Jim,
> Looks like I missed something did not see anything from Mike just saw
> your response. Is it some sort of spectrograph or spectrometer?
> 
> 
>> On Mon, May 14, 2018 at 11:32 PM, Jim Moss <n9jim-6 at pacbell.net> wrote:
>> 
>> Mike,
>> Looks like that is pretty cheap.
>> Looks like it is about 3nm resolution, and about 2 month delay to shipment.
>> You have to calibrate it yourself.
>> Might be interesting.
>> Let us know how it goes.
>> Jim
>> 
>> 
>> Sent from my iPad
>> 
>>> On May 14, 2018, at 8:08 PM, Chuck Hast <wchast at gmail.com> wrote:
>>> 
>>> 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
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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
> Home: http://mailman.qth.net/mailman/listinfo/laser
> Help: http://mailman.qth.net/mmfaq.htm
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