Barlow lens [SEP] named after
Barlow lens
The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system. The practical result is that inserting a Barlow lens magnifies the image.
A real barlow lens is not a single glass element, because that would generate chromatic aberration, and spherical aberration if the lens is not aspheric. More common configurations use three or more
engineering.
In collaboration (1827-1832) with optician George Dollond, Barlow built an achromatic lens that utilized liquid carbon disulfide. (Achromatic lenses were important optical elements of improved telescopes.) In 1833, Barlow built an achromatic doublet lens of joined flint glass and crown glass. A derivative of this design, named a "Barlow lens", is widely used in modern astronomy and photography as an optical element to increase both achromatism and magnification.
In 1823, he was made a fellow of the Royal Society