Who was considered the greatest experimenter of antiquity, and was one the first to describe specular reflection?
Specular reflection: Specular reflection, also known as regular reflection, is the mirror-like reflection of waves, such as light, from a surface. Specular reflection:  This behavior was first described by Hero of Alexandria (AD c. 10–70). Hero of Alexandria:  He is considered the greatest experimenter of antiquity and his work is representative of the Hellenistic scientific tradition.
Hero of Alexandria