Conventionally, for the most accurate measurements, interferometer systems are constructed from high-quality optical elements and include fine controls for precise alignment. In this alternative approach, all the errors of a poor quality, misaligned system are accepted then eliminated by a simple digital moire´ process. The method offers the possibility of devising very large aperture optical systems for traditional and engineering interferometers from inexpensive and basic components. It can also offer benefits in other measurement techniques, including moire´. © 2001 Society of Photo-Optical Instrumentation Engineers.