SBIR-STTR Award

As an alternative to holographic laser radar, AMPS will develop a 3-D imaging concept that collects far-field intensity speckle patterns. This kind of measurement greatly relaxes the tolerances on vibration and coherence length. However, phase retrieval will be required to retrieve a 3-D image. Phase retrieval algorithms typically utilize some type of prior knowledge about the object. In industrial metrology and missile-imaging problems the objects will be opaque to the illumination and will appear as a warped 2-D surface embedded in a 3-D space. The opacity constraint promises to be very powerful since it greatly reduces the class of feasible objects from which to choose an estimate. We propose to demonstrate, in computer simulation and with laboratory data, 3-D imaging of opaque objects by using phase retrieval.

Three-dimensional (3-D) imaging provides profile(surface shape) not available with 2-D imaging.Profile information is extremely useful in problems such as discrimination, identification,and surface metrology. Phase 2 will further develop a novel 3-D imaging modality referred to as Phase Retrieval with an Opacity Constraint inLAser IMaging (PROCLAIM). PROCLAIM is anactive-illumination imaging method that requiresthe object to be flood illuminated with afrequency-tunable laser. The far-field speckleintensity pattern is direct detected withoutintervening optics for each of multiple laserfrequencies. A phase-retrieval algorithm, thatutilizes an opacity constraint, is required toreconstruct the 3-D object. PROCLAIM is arelatively high-risk baseline technology. Phase 2proposes to develop robust phase-retrievalalgorithms, to increase the computational speed,to quantify performance as a function of key imaging parameters, and to demonstrate PROCLAIM ina shop environment.PROCLAIM sensor technology provides a method formeasuring 3-D shape of objects for a variety ofapplications. In the field of industrialinspection, PROCLAIM offers the ability to makerapid, non-contact, and precise measurements ofcomplicated surface shapes, which are common inmodern manufacturing processes. PROCLAIM can alsobe used for long-range shape measurement, referredto as remote target characterization, which isimportant for applications such as missile andaircraft identification.

Keywords:
3-D IMAGING LASER IMAGING OPACITY PHASE RETRIEVAL PROFILE RETRIEVAL SURFACE METROLOGY