Ramsden
/ˈramzdən/Optics
noun
Attributive and (now rare ) in the genitive. Designating an eyepiece consisting of two planoconvex lenses of equal focal length with their convex surfaces towards each other and a separation less than their focal length.
- This arrangement has the focal plane outside the eyepiece, and so lends itself to use with a graticule or cross hairs..
Origin
Late 18th century; earliest use found in Philosophical Transactions of the Royal Society of London. From the name of Jesse Ramsden, English instrument-maker, who described the eyepiece in 1783 (Philos. Trans. (Royal Soc.) 73 94).
- come to nothing
- come to (or meet) a sticky end
- come to pass
- come to rest
- come to someone's assistance
- come to someone's knowledge
- come to terms with
- come to that (or if it comes to that)
- come to think of it
- come true
- come under
- come unglued
- come up
- come up against
- come up against (or hit) a brick wall
- come up dry
- come upon
- come up (or be given) with the rations
- come up (or go down) in the world
- come up (or out) smelling of roses
- comeuppance
- come up roses
- come up smiling
- come up with
- come up with (or deliver) the goods