Abstract
Packaging of electronic and photonic components requires high accuracy, which has to be preserved not only in the process of manufacturing, but also in the process of operation. Therefore, products that are built using microelectronic components are subjected to extensive reliability testing. Shifts in alignment, both linear and rotational, could occur with time or simply because of the temperature variations and the associated expansion/contraction of the materials. Identifying where these problems occur and obtaining quantitative results with sub-micron accuracy could potentially be achieved by photometric measurements. Unfortunately, many conventional techniques are virtually useless when measurements are performed on diffuse objects, such as photonic packages. These limitations can be avoided using holography, which facilitates recording and reconstruction of the optical waves reflected from any surface. In the process of reconstruction it is possible to reproduce not only the amplitude of the reflected wave, but also its phase distribution, which carries information about the distance to each point illuminated with light. An optical technique developed by our group and presented in this paper is based on holographic interferometry. The main goal is to make this technique suitable for reliability testing, which provides vital information for modifications in the design or the packaging process.