We propose to develop ultra-compact arrays of multi-wavelength diode lasers having excellent beam quality for use in ophthalmology and other medical imaging applications. The proposed arrays are based on vertical- cavity surface-emitting lasers (VCSEL). Unlike conventional diode lasers, VCSELs emit low-divergence, circularly-symmetric beams which are free from astigmatism, and are thus ideally suited for imaging applications. The targeted configuration is an array of VCSELs, each with a different wavelength, which are efficiently combined and fed through an optical fiber into a scanning laser ophthalmoscope (SLO). Our design maintains constant alignment of the source with no moving parts and allows rapid, programmable electronic switching between the lasers. For Phase I we will: 1) Produce VCSELs to be used in a SLO to demonstrate their suitability; 2) Evaluate the performance of the VCSEL- equipped SLO; 3) Determine the extent of wavelength variation which is feasible for a single chip; 4) Investigate techniques for mounting and aligning multiple laser chips on a common substrate; 5) Determine the optimal means for combining the beams; 6) Survey the range of other medical imaging applications and requirements for similar arrays; 7) Report our results and plan construction and implementation of the wavelength-multiplexed source array for Phase II.
