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Single Mode Diodes

Eidetical

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May 14, 2022
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43
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18
Did anyone mention coherence length for laser in an interferometer?
It needs to be as large as possible. Often with diode lasers, one may see fringes all the time and think the coherence length is very long. It's possible that it is really short, and just repeats at very short intervals. A holographic image featuring the "sliced bread" look is a good example of this.
 



kecked

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Jun 18, 2012
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751
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Measure small angles by putting a mirror on a string and bouncing the laser off it onto a wall. Put a small magnet on the back of the magnet and use a coil to make a magnetic field. Essentially a small motor. When you apply current the mirror should move. Now figure how to calibrate it…. Does the angle change linearly? If not what does that mean about the string?

put a polarizing filter over the laser and turn it so you see the brightest light. Now bounce this off surfaces and observe the beam through a second polarizer. Did the angle of the polarizer change? Is it still the same.

redo the double slit experiment.

observe scattering in water and other liquids.

lots to do.
 

Eidetical

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Here's a late-'60s interferometer set up with a late-80s He-Ne laser showing better fringes than the pic shows. My whole career has been about making fringes, and making them hold still to record them.

OTI-176 Setup.jpg
 

Singlemode Laser

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Jun 25, 2017
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Here's a late-'60s interferometer set up with a late-80s He-Ne laser showing better fringes than the pic shows. My whole career has been about making fringes, and making them hold still to record them.

View attachment 74734

So what's the insight here? You can make perfect fringes with a lightbulb ( double slit experiment ) Congratulations to your long experience, but I don't see any additional information here ( The fringes look very nice though)

Singlemode
 

Eidetical

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May 14, 2022
Messages
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Points
18
So what's the insight here? You can make perfect fringes with a lightbulb ( double slit experiment ) Congratulations to your long experience, but I don't see any additional information here ( The fringes look very nice though)

Singlemode
The OP said they sought a single mode laser to make an interferometer. I thought a pic of nice fringes on one might encourage him, or possibly her, probably going more for entertainment and/or education than insight. ;)

Of course there's "additional information". You're saying the additional information isn't insightful, right? Your opinion, no problem. I don't disagree. But isn't "insight", like beauty, in the eye of the beholder? 💡
 

kecked

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Messages
751
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63
He was looking for things to do with a single mode laser. I forgot to add holography
 

Singlemode Laser

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Jun 25, 2017
Messages
348
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The OP said they sought a single mode laser to make an interferometer. I thought a pic of nice fringes on one might encourage him, or possibly her, probably going more for entertainment and/or education than insight. ;)


Nice from you. Lasers as intertaiment for a new laser fan is high priority.
Of course there's "additional information". You're saying the additional information isn't insightful,
Nope, every bit added to this forum is additional information. Insightful or not depends on the contact

Nope

Your opinion, no problem.
Of course there is no problem with a personal opinion.

I don't disagree. But isn't "insight", like beauty, in the eye of the beholder? 💡

This statement makes every content here completely up to the eye of the beholder. We can than post kittens again?


Singlemode
 




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