The phrase "a single ray of" is correct and usable in written English.
It can be used to describe a small amount of light or hope in a situation, often metaphorically.
Example: "In the midst of despair, she found a single ray of hope that kept her going."
Alternatives: "a glimmer of" or "a beam of".
His shock of white hair gleamed in a single ray of light falling from the girl's yard into his.
I do not know how I spent the spring; I didn't see a single ray of sunshine.
Near the end of his speech, Trump said that "even the most terrible despair can be illuminated by a single ray of hope".
From a passing boat, you might not even notice it, but inside it is astonishing -- a single ray of sunlight pierces the roof of the cave like a spotlight, surrounded by deep womblike darkness. .
Often, a single ray of the tomographic experiment is modeled as a line, with the element (w_{ij}) of ({mathbf {W}}) equal to the intersection of pixel j with the line corresponding to ray i.
A single ray of sunlight through white cotton curtains.
A projection of a single ray is regarded as the integral of the absorption over the straight line.
Even beyond this first order result, we show that for NA≲ 0.2 the computation involved in calculating beam contrast can be reduced to the equivalent of tracing a single ray (in double-pass), despite the fact that contrast along different rays in the beam will vary as a function of both the skew component and incidence angles of the rays at coatings.
In the midst of assembled classmates, a single ray shines on one woman.
Described in the book as the single "ray of sunshine" in Mr. Gucci's life, Ms. Loud refused to return Ms. Forden's calls.
This implies that a single, new ray is generated, instead of the impinging ray, while all significant phenomena (reflection, penetration, absorption and diffraction) are taken into account.
