Diffraction of red LED light picture with spots

In summary, the conversation is about taking pictures of a small glass nozzle with a metal coating and a sphere of liquid at the end. The pictures were taken with low light and a single red LED, with some overhead white lights. The LED light hits the sphere of liquid at an angle and is pulsing at 10 Hz. To make the image brighter, a mirrored surface was placed under the nozzle. The exposure time was shortened and the overhead lights were turned off. There was no change in focus, magnification, or object position. The final image shows the object in better focus, but the depth of focus is not as large as the sphere of liquid.
  • #1
phrendlie
2
0
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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  • #2
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
 

1. What is diffraction of light?

Diffraction of light is the bending or spreading of light waves as they pass through a narrow opening or around an obstacle. This can create a pattern of light and dark spots, known as a diffraction pattern.

2. What causes the spots in a diffraction pattern?

The spots in a diffraction pattern are caused by the interference of light waves as they pass through an opening or around an obstacle. This interference creates areas of constructive and destructive interference, resulting in the pattern of spots.

3. How does the color of light affect diffraction?

The color of light does not have a significant effect on diffraction. However, different colors of light may have slightly different wavelengths, which can slightly alter the spacing and size of the diffraction pattern.

4. Why is the diffraction pattern for a red LED light different from other colors?

The diffraction pattern for a red LED light may appear different from other colors because the red light has a longer wavelength than other colors, which can result in a larger diffraction pattern with wider spacing between the spots.

5. How is diffraction used in real life?

Diffraction is used in many practical applications, including optical instruments such as microscopes and telescopes. It is also used in the production of holograms and in the study of crystal structures in materials. In addition, diffraction is used in everyday items such as CD and DVD players, which use diffraction gratings to read information from the discs.

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