Diffuse optical mammography is a special way of looking at the breasts of grown-up ladies to make sure they are healthy.
To do this, a special machine with special cameras is used to shine light through the breast tissue. This light is kind of like a "flashlight" that lets the doctors and scientists see what's inside the breasts.
The way the light moves and bounces around tells the doctors and scientists important things like how much blood is flowing through the breast tissue, and if there are any lumps or bumps that shouldn't be there.
This kind of special camera is also used for other body parts like the brain or muscles, but for ladies it's used to keep their breasts healthy and happy!