Can't he use lean startup principles to launch with his existing device that offers an improvement over a cane, instead of raising $15 MM to offer a perfect product that lets blind people play tennis? If I were blind, I would surely pay thousands of dollars for the K-Sonar device if it could enhance my sensory input beyond "what I feel with my cane within 2 feet" to "everything around me within 15 feet".

If he got the K-Sonar approved as a medical device, I think he'd be able to get paid from deep-pocketed insurance companies too.

Improving the range (and doing research on inner-ear microphone implants) could be done in later versions (if mainstream blind customers really are interested in playing tennis, which I am skeptical about). If v1 makes people more independent, that's a huge deal already!

I bet he could get pretty far just by reallocating his existing $200k/year budget to commercializing the technology, which has the potential to be embraced by a lot more people than the blind people he is introduced to (only 10% of whom even get good at echolocation-through-clicking).