The phrase "a patch of light" is correct and usable in written English.
You can use it to describe a bright spot in a location that is generally dimly lit, for example: "As I walked through the dark hallway, I noticed a patch of light coming from a crack in the door at the end of the corridor."
The button was nothing but a patch of light on the palette.
Director Elizabeth Freestone rightly opts for a simplicity of staging: a shadow looms out of the darkness; a patch of light suggests a bedroom door ajar with possibilities.
In the foreground, a young couple is seated under a parasol, in a patch of light, happily oblivious to the fury of the elements about to be unleashed.
But Coast Guard officials said on Friday that only a patch of light rainbow sheen, measuring about 100 yards by 10 yards, had been spotted in morning flights over the area around the platform.
It did so most devastatingly in Augusta three years ago when he finished second to Phil Mickelson after the American had produced a career shot from a carpet of pine needles, a stunning invention fashioned in a patch of light between the trees.
Experiments, in which 60 percent was arbitrarily taken as the frequency of seeing and in which the image of a patch of light covered an area of retina containing about 20,000,000 rods, led to the calculation that the mean threshold stimulus represents 2,500 quanta of light that is actually absorbed per square centimetre of retina.
It is there that light is processed by the retina: a patch of light-sensitive photoreceptor cells that sends signals down the optic nerve to the brain.
"You see that circle there?" he says, pointing to a patch of lighter tan near the top.
Figuring out how a patch of light-sensitive receptors evolved into a camera-like imaging system shared by 40,000-odd species of vertebrates is certainly an important thing to do, and it is a job that will fill many scientists' entire careers.
Mao lies in a dim chamber, garbed in a grey suit, his sallow waxy face framed by thick black hair bathed in a patch of orange light.
In a patch of red light, all three men lie on their backs with their pants pulled down around their ankles; as their moans rise in volume and pitch, so do their pelvises.
