Carl Friedrich Cassegrain

Carl Friedrich Cassegrain was a 17th-century French mathematician and astronomer known for inventing the Cassegrain telescope. This type of telescope uses two mirrors—an angled primary mirror and a smaller secondary mirror—to fold the light path, allowing for a compact design that can produce high magnification images. The Cassegrain design is popular in astronomy because it combines a long effective focal length with a more manageable size and weight. His innovation improved the efficiency and practicality of large telescopes, advancing the study of celestial objects.