diverging lens
concave lens

The concave lenses of these mirrors were found to form parabolic reflectors.

While not shown on the series, Chan was also instrumental in the creation of fire using spectacles (something not normally possible with concave lenses).

Thus this laser does not need a concave lens or refocusing lenses and beam quality improves along the gain medium.

He developed an occhiolino or compound microscope with a convex and a concave lens in 1609.

It is corrected by the use of a concave lens.

You could look in Edmund Optics for a concave lens of, say, 10mm diameter and -50mm focal length.

That is a negative number for concave lenses, which cannot really bring a light beam to a focal point.

When we look into a convex mirror or see through a concave lens, what we see is not a real image.

A concave lens can push the focus back (bottom).

The focal length f is considered negative for concave lenses.