This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Lanature telescope cassegrain. Fig Coupe du tlescope de Cassegrain pour La Nature revue des sciences page cnam fr cgi KY author This image is in the public domain because its copyright has expired La Nature Revue des Sciences Reflecting telescope diagrams PDold
Page 2023 Free-images.com. All images are Public Domain