Complex sentence: In 1902 he realized that revert the two rear elements of Unar back into a cemented doublet will improve the performance of Zeiss Unar lens, he named it "Tessar", from the Greek word τέσσερα to indicate a four element design.
Split into simpler sentences: In 1902 he realized that to revertse the two rear elements of the Unar back to a cemented doublet would improve the performance of Zeiss Unar lens. He named it "Tessar", from the Greek word τέσσερα to indicate a four element design.