I'm trying to think through a new experimental set-up, involving a sheet of water being shot up over a step structure. The water sheet will be about 5" wide, and the camera will be positioned orthogonally to the flow direction. I'd like to take some high-speed images of a single cross-section of the resulting water spray/jet, preferably near the center of the stream. But to do this, the camera has to see through ~2-3" of a complex water/air flow (i.e, the water between the center of the spray and the camera).
Obviously, a ray of the light that's making its way from the center of the spray to the camera will be forced to interact with the jet and droplets (of various sizes) that are between the center of the spray and the camera, which can't be good for image quality. Every time the rays have to pass through another globule of water, they'll be diffracted and reflected and all messed up. I've thought of a few approaches that might improve the output:
- Illuminate the center of the spray with a laser sheet, paired with the appropriate filter on the camera, such that only the light hitting the center of the spray will make it to the camera sensor.
- Minimize the camera/lens depth of field, so that light from outside the desired cross-section is out of focus, as much as possible.
- In terms of post-processing, I'm hoping that some background subtraction will improve the quality.
None of this will fix the problem, but I'm hoping it will mitigate it. My gut is unsure of the magnitude of the problem, as well - will I just get slightly messy/blurry images, or will I get complete garbage? Does anyone here have advice or experience? Any suggestions on how to estimate the optical impact of the water splashes before I spend a couple thousand $$ on laser equipment, etc?
