an apparatus for testing an optical surface comprising an array of holograms . the array includes a plurality of individual holograms arranged in an m × n format , in which m is the number of rows and n is the number of columns in the array . the array of holograms is positioned between the optical surface and a wavefront sensor . the array of holograms reflects a reference beam back to the wavefront sensor , and transmits a test beam to the optical surface . the array of holograms also receives the test beam reflected from the optical surface and transfers the test beam back to the wavefront sensor .