Rainy, foggy days are becoming more common as we move into the autumn and winter months. If you’ve ever clicked on your bright beams to cut through the fog, you know it only makes it harder to see.
Researchers working with the Optical Society are developing technologies to make it easier to see clearly, even when conditions make it hard to navigate the road ahead.
Changhuei Yang’s team from the California Institute of Technology in Pasadena are working on a type of noise-canceling camera that would reduce glare by a factor of 10. The method cancels out glare with illumination that matches the coherence of the glare but not the reflection of the object under view, according to the Optical Society. Light is coherent when the peaks and troughs of its waves are the same size.
“We are trying to invent a type of noise-canceling camera by separating the glare from the target’s reflection so that the target can easily be seen,” said Edward Haojiang Zhou, a graduate of CalTech and a researcher on the project.
The approach can produce images of an object placed 2 mm behind a 1 mm-thick light-scattering sample, making it a promising approach for microscopy.
“By changing the coherence of the light, the method we demonstrated can be used to simultaneously image objects at various distances from the light source,” said Zhou. “This provides a great deal of freedom for imaging through scattering samples with thickness from 1 mm to a kilometer.”
Some other approaches that compensate for glare require expensive and complicated equipment, but this setup, the researchers claim, uses basic and readily available optical components.
The technique is now being used to improve the quality of images taken by satellites.
Meanwhile, Yaron Silberberg’s research team from Israel’s Weizmann Institute of Science demonstrated a similar approach to Zhou’s, but this method reduces glare by using wave-front shaping to change the field of the light illuminating the object.
This approach minimizes the amount of blinding light scattered into the camera by using an optical device called a spatial light modulator and an optimization algorithm to control the shape of the impinging light field.
Wave-front shaping has been used for some time to improve imaging in microscopy and astronomy applications.
“Almost all other work with wave-front shaping involves trying to maximize the amount of light that will be received by the camera,” said Silberberg. “In this work, we are trying to do the opposite by minimizing the amount of light that is reflected.”
The wave-front shaping method requires that the light from the object and the background by mutually incoherent. The glare must be fairly static for the optimization process to be effective.
Filed Under: Rapid prototyping
