Phase retrieval for optical inspection of technical components

We demonstrate optical inspection of a technical component under thermal load by means of phase retrieval. The scheme is based on the determination of the phase distribution of light scattered by an object using phase retrieval from a set of intensity measurements. In contrast to already existing configurations, the employed setup enables a rapid acquisition of the required intensity distributions, thus the slow changes of the object's surface during the thermal loading can be tolerated in the subsequent evaluation process. The presented system exhibits all the properties of an inspection system based on phase shifting interferometry, yet it does not require a reference wave, which makes it more tolerant against environmental disturbances and therefore a preferred choice for future industrial applications.