Diffraction of red LED light picture with spots

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SUMMARY

The discussion centers on the diffraction patterns observed from a red LED light interacting with a liquid sphere at the end of a microcapillary nozzle, specifically a 2um inner diameter glass nozzle with a sputtered gold coating. The sphere, with a radius of approximately 10 to 20 um, is illuminated at a 120-degree angle, causing the light to bend significantly before reaching the camera. Long exposure times of 1 second and 8 ms were utilized to capture the images, revealing distinct diffraction spots influenced by the pulsing LED light at 10 Hz and the reflective properties of the setup.

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  • Understanding of optical diffraction principles
  • Familiarity with microcapillary nozzle design and applications
  • Knowledge of camera exposure settings and their effects on image capture
  • Basic principles of light behavior in liquids, including refraction
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  • Investigate the effects of light refraction in spherical liquids and their imaging implications
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Optical physicists, imaging specialists, and researchers in fluid dynamics who are interested in the behavior of light in micro-scale environments and diffraction phenomena.

phrendlie
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I would like to know what the dots are. This reminds me of X-ray diffraction, but I am imaging a sphere of liquid on the end of a microcapillary nozzle (2um inner diameter glass nozzle with sputtered gold outer coating on nozzle).
I am taking a picture of a small glass nozzle with a metal coating. There is a sphere of liquid at the end of the nozzle This sphere has radius ~10 to 20 um. Then I lowered the lights and took a long exposure (1 second). The lighting is a single red LED, with some overhead white lights.
The LED hits the sphere of liquid at ~120 degrees to the camera with the light coming from behind the object. By this, I mean that the light has to bend ~60 degrees within the sphere to reach the camera. The LED light is pulsing at 10 Hz.
Low light, long exposure (1 second) with overhead lights on:
upload_2015-12-17_22-28-46.png

Same, with overhead lights off:
upload_2015-12-17_22-30-59.png

Then I put a mirrored surface under the nozzle to make the image brighter (requiring shorter exposure time)
Exposure time 8 ms, no change in focus or magnification, no change in light, camera, or object position. Overhead lights off, so all light is red, nearly monochromatic:
upload_2015-12-17_22-37-42.png
 
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If it helps, here is the object in better focus, but notice that my depth of focus is not even as big as the sphere of liquid:
upload_2015-12-17_23-0-25.png
 

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