On the precision alignment and hybrid assembly aspects in manufacturing of a microspectrometer

Microoptics is a fertile area for hybrid assembly of miniaturized components, due to the need to integrate different optical and actuation materials in a single precision bench. In this paper we discuss issues related to the assembly and alignment of a microspectrometer using 3D miniature non-silicon objects such as glass lenses, optical fibers, laser sources, and detectors onto silicon fixtures and microactuators. The resulting instrument, a fiber-coupled MOEMS spectrometer, requires high alignment precision, because it is based on interference fringes from a Michelson Interferometer bench. Our fiber-coupled Fourier-Transform microspectrometer has a nominal packaged size of 3 cm times 3 cm times 3 cm, and targets wavelengths in the visible and NIR spectra. We use modular microscale parts, including minimum energy compliant MEMS fasteners to configure a die-sized (1 cm times 1 cm times 0.5 cm) microoptical bench. We discuss the tolerance of this complex assembly, and present experimental results validating the automated assembly and alignment of the optical components on the microbench.