Which companies were responsible for grinding and testing the flawed primary mirror, respectively?

Perkin-Elmer and Kodak

The responsibility for the physical fabrication and the initial verification of the primary mirror involved two distinct entities. Perkin-Elmer was the contractor tasked with the complex process of grinding and polishing the massive piece of glass to the required specifications. Following this fabrication step, Kodak performed the ground-based testing to verify the mirror's figure before it was deemed acceptable. The ultimate root cause was traced back to the testing phase—specifically the faulty setup involving the null corrector used by Kodak's verification process—rather than the actual grinding skill of Perkin-Elmer, who fabricated the mirror according to the flawed test specifications provided.