What is Cassegrain?
A Cassegrain is a type of reflective telescope. The telescope has two mirrors, a primary and a secondary. The primary mirror is a concave parabolic mirror, while the secondary is a convex hyperbolic mirror. The primary mirror focuses light onto the secondary mirror, which is then reflected through a hole in the primary mirror into the eyepiece for viewing. The Cassegrain was first discussed in 1672 and was the apparent invention of its namesake, the priest Laurent Cassegrain. Papers uncovered after his death showed the basic design for the telescope. It is unsure if he was the original inventor or if the design came from another first, but the telescope still bears his name as it did when it was first introduced. An object is viewed through the far end of the telescope and reflects onto the parabolic secondary mirror which is at the opposite end of the telescope. This mirror reflects the image back onto the smaller parabolic primary mirror, which is placed toward the open end facing th
