  Recent advancements in whole slide imaging (WSI) have moved pathology closer
to digital practice. Existing systems require precise mechanical control and
the cost is prohibitive for most individual pathologists. Here we report a
low-cost and high-throughput WSI system termed OpenWSI. The reported system is
built using off-the-shelf components including a programmable LED array, a
photographic lens, and a low-cost computer numerical control (CNC) router.
Different from conventional WSI platforms, our system performs real-time
single-frame autofocusing using color-multiplexed illumination. For axial
positioning control, we perform coarse adjustment using the CNC router and
precise adjustment using the ultrasonic motor ring in the photographic lens. By
using a 20X objective lens, we show that the OpenWSI system has a resolution of
~0.7 microns. It can acquire whole slide images of a 225-mm^2 region in ~2
mins, with throughput comparable to existing high-end platforms. The reported
system offers a turnkey solution to transform the high-end WSI platforms into
one that can be made broadly available and utilizable without loss of capacity.
