Abstract A system for monitoring the optical figure of a surface utilizes an interferometer and a source of light to provide a measuring beam and a reference beam. Reflective spots are mounted respectively at a number of sample points on the surface and the measuring beam of light is focussed by optical means to provide an image field that includes the reflective spots which are oriented to reflect light from the measuring beam back to the optical means to form a conjugate image of the field of spots on light intensity detectors. The reference beam, whose path length is modulated, is combined with the light reflected from the spots to the detectors. There are separate detector elements for measuring the intensity of the combination of reference beam light and measuring beam light reflected from at least two different spots at one time. A shift in position of one sample point forward or back in relation to another sample point, which is a reference point, is thus monitored by comparing the phase relationship of the combination of the reference light with reflected light derived simultaneously from at least a pair of the sample points.
A system for monitoring the figure of a surface by detecting shifts of at least two spaced sample points on said surface from predetermined positions thereof comprising: light reflecting elements disposed respectively at said points, each of said elements being individually oriented and constituted to reflect light to a preselected focal point disposed in a location independent of the radius of curvature of the surface being monitored, each of said elements having a detectably different reflective capacity with respect to the adjacent portion of said surface with respect to said focal point, means including interferometer means and detecting means for directing a beam of light at said elements and comparing the intensity of the light reflected from one element with respect to the other elements.
Claim 2
Independent Claim
125 words
A system for monitoring the figure of a surface by detecting shifts of at least two spaced sample points on said surface from predetermined positions thereof comprising: light reflecting elements disposed respectively at said points, each of said elements being individually oriented and constituted to reflect light to a preselected focal point disposed in a location independent of the radius of curvature of the surface being monitored, each of said elements having a detectably different reflective capacity with respect to the adjacent portion of said surface with respect to said focal point, means including interferometer means and detecting means for directing a beam of light at said elements and comparing the intensity of the light reflected from one element with respect to the other elements.
Claim 3
Dependent Claim
16 words
A system according to claim 1 wherein said interferometer means is an unequal path length interferometer.
Claim 4
Dependent Claim
85 words
A system according to claim 1 wherein said means including interferometer means and detecting means for directing a beam of light at said elements and comparing the intensity of the light reflected from one element with respect to the other elements includes optical means for focusing a collimated beam of light and defining a field including said light reflecting elements, said detecting means and said optical means being positioned for a conjugate image of said field of elements to be formed at the detecting means.
Claim 5
Dependent Claim
28 words
A system according to claim 3 wherein said detecting means includes means for separately detecting the intensity of the light reflected from at least two of said elements.
Claim 6
Dependent Claim
18 words
A system according to claim 1 wherein said surface is a mirror surface in a Cassegranian optical system.