A DSLR camera takes a long-exposure photo of the moving single white light LED source. In image, OSA is made up of two colors, red and white. When I put finger on LED source, color of light becomes red due to human tissue and that corresponds to red color in image, otherwise its white. While my presence is not captured due to very little reflection from my body.
—Monika Choudary, Indian Institute of Technology Delhi, New Delhi, India
20 Nov 2017