Ignazio Porro

Ignazio Porro (1801 to 1875) was an Italian military engineer who surveyed land and improved geodetic instruments. Around 1839 he began calling his instruments tachymeters and coined the term tachymetry for rapid surveying. He is best known for a prism image-erecting system, now used in binoculars and stereomicroscopes and called the Porro prism. He moved to Paris, where he patented his direct-vision prism in 1854, and he is reported to have built mostly monocular instruments with the new prism system. He was never able to produce his designs on a large scale, received little recognition in his lifetime, and was in serious financial hardship when he died in 1875. His designs became popular only after his death, when others refined Porro prism binoculars.