Telescopes
Professor Väisälä was an inventor and developer. In Iso-Heikkilä he had invented a new wide-field telescope on 1929, but considered the structure so obvious that left his plans in a desk drawer. The next year Estonian Bernard Schmidt (1879-1935) published the same structure, which was named after him.
Väisälä built several telescopes in Tuorla and planned for a giant zenith telescope that never produced expected results. He built a "crepe pan telescope" (photo) into the red test dome in 1949. It was never finished.