When I pass the laser light on, one of my nano-assembly results circularly polarized patterns. Please refer photos in the attachments.
I think it is so-called Airy diffraction pattern https://en.wikipedia.org/wiki/Airy_disk
Selvaraj Nagarajan , it looks like your nano-assembly has most of the particles of the same size and you see result of first and second orders of diffraction on your assembly.
To verify this model you can compare angular radii of the first and second circles. Angular radius is
phi = arctan(r/L),
where r and L are radius of the circle and distance between sample and screen for the case of normal beam incidence.
For the diffraction mechanism second angular radius have to be twice bigger than first one.
You can estimate average size of your particles d from following relationship:
d * sin(phi) = k * lambda
where phi is angular radius, half angle of the circle of order k, and lambda is laser wavelength.
As well, you could compare d with particles size while seeing your assembly by optical microscope. You can directly measure average particles size and how narrow is size distribution function.
Selvaraj Nagarajan , it looks like your nano-assembly has most of the particles of the same size and you see result of first and second orders of diffraction on your assembly.
To verify this model you can compare angular radii of the first and second circles. Angular radius is
phi = arctan(r/L),
where r and L are radius of the circle and distance between sample and screen for the case of normal beam incidence.
For the diffraction mechanism second angular radius have to be twice bigger than first one.
You can estimate average size of your particles d from following relationship:
d * sin(phi) = k * lambda
where phi is angular radius, half angle of the circle of order k, and lambda is laser wavelength.
As well, you could compare d with particles size while seeing your assembly by optical microscope. You can directly measure average particles size and how narrow is size distribution function.
Nikolay Pavlov and Valeriy Sterligov, Thank you so much for your suggestions.
Nikolay Pavlov , at least, according my experience, width of rings of Airy structure is comparable with radial distance between them. This is not the case according presented images.
Valeriy Sterligov Agree, I guess it might be caused by the fact that it is a sum of diffraction from many small particles. Also, image processing potentially might somehow non-linear but usually it would rather broaden the light not dark strips due to clipping.
By the way, careful linear registration of intensity dependence vs phi will give possibility to calculate particles' size distribution function.
If laser beam is circularly polarized it will be useful to perform circular averaging of measured intensity distribution to increase signal/noise ratio and decrease influence of speckle structure.
A very good account is given in Volume 3 Waves by Crawford. Berkeley Physics Course. However what you are getting is not circular polarization. You are getting circular patterns resulting from interference effects most probably not from nano particles.
The pattern where you have the nanoparticles is blocking the light. Light not going through the nanoparticles. Could be.
Dear Sohail Khan, could you please give the chapter or page number deatils about this book " Waves of Volume 3 by Crawford. Berkeley Physics Course"
Dear Prof.Valeriy Sterligov,
With the help of your answer.
We can able to published the paper in polymer
https://doi.org/10.1016/j.polymer.2022.125264
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