In 1968, those of us at NBS concerned with classical optics, felt it important to resume the testing of optical systems and components and decided to develop a method that was in keeping with the advances being made in lens design and manufacture. The technique previously used at NBS1 was limited to about 200 cycles/mm by considerations of partial coherence, and could measure phase shifts only with great difficulty and low precision. The forthcoming high-quality optics indicated by activity in the design community were clearly beyond the capability of this testing system. Further, the increasing use of microscope optics in such devices as microdensitometers, reduction cameras and other specialized equipment showed the need for an accurate testing technique that would include these kinds of optical components. Our intent was to concentrate on the test and evaluation of high-quality optics such as might be used in microdensitometry, microelectric circuit applications, and high resolution aerial cameras, to develop an inexpensive and accurate measurement technique, and to provide a modest NBS measurement service that would be used by commerical firms and other government agencies when it was necessary (for contractual reasons) to have the NBS imprimatur on the results or when it was impractical for the requestor to have his own test equipment.