This invention relates to the precision measurement of angles by optical means. More particularly it relates to apparatus which utilizes an echelle or blazed grating in a spectrometer interacting with the optical output from a dispersive element on the object of interest to achieve great sensitivity of movement of the resulting patterns on a detector.
The ability to measure angles to submicroradian accuracy is necessary for a variety of advanced applications. Increased accuracy in the alignment of existing instruments will allow for increased accuracy in their measurements and actions. Ion beam mapping of microstructures could be made much more detailed. Ion beam etching of microelectronic arrays could produce smaller and faster devices. The need in space technologies is particularly acute. Long range space communications require very accurate alignment of antennae. The same is true if long range beam power transmission is to be feasible, e.g. microwave, laser or particle beam. This level of accuracy is also needed for specialized scientific missions such as gravitational wave detection and precision astronomy.
At present the state of the art is represented by the autocollimator. It is capable of just microradian accuracy, and the physics of the device restrict it past a certain level. What is needed is a low cost, compact device that can achieve even better accuracy in measuring angles than the autocollimator.