Apparatus and method for optical determination of intermediate distances

An apparatus for optical determination of distance to a feature, said apparatus comprising:

• a) a beam generation unit for launching a reference beam on a reference path, a first beam on a first path and a second beam on a second path;
• b) a rotation mechanism for rotating said reference path, said first path and said second path about a center along a line of said reference path and not along a line of said first path, whereby said reference beam moves over said feature at a reference time tr, said first beam moves over said feature and at a first time t1 and said second beam moves over said feature at a time t2;
• c) a determination unit for determining a distance r from said center to said feature from an angular velocity ω of said reference beam over said feature from said times tr, t1, and determining said angular velocity ω of said reference beam from said times tr, t2.

An apparatus for optical determination of distance to a feature, said apparatus comprising:

• a) a radiation detection unit for detecting radiation on a reference path and on a first path;
• b) a rotation mechanism for rotating said reference path and said first path about a center along a line of said reference path and not along a line of said first path, wherein said line of said reference path and said line of said first path are non-parrallel, and whereby said radiation from said feature is detected on said reference path at a at a reference time tr and on said first path at a first time t1;
• c) a determination unit for determining a distance r from said center to said feature from an angular velocity ω of said reference path over said feature and from said times tr, t1.

A method for optical determination of distance to a feature, said method comprising:

• a) launching a reference beam on a reference path and a first beam on a first path;
• b) rotating said reference path and said first path about a center along a line of said reference path and not along a line of said first path, wherein said line of said reference path and said line of said first path are non-parrallel, and whereby said reference beam moves over said feature at a reference time tr and said first beam moves over said feature at a first time t1;
• c) determining a distance r from said center to said feature from an angular velocity ω of said reference beam over said feature and from said times tr, t1.

A method for optical determination of distance to a feature, said method comprising:

• a) providing a reference path and a first path for a radiation;
• b) rotating said reference path and said first path about a center along a line of said reference path and not along a line of said first path, wherein said line of said reference path and said line of said first path are non-parallel, and whereby radiation from said feature is detected on said reference path at a reference time tr and on said first path at a first time t1;
• d) determining a distance r from said center to said feature from an angular velocity ω of said reference path over said feature and from said times tr, t1.