Presently disclosed is a lighting system and methods of using the lighting system for in vitro potency assay for photofrin. The lighting system includes a lamp housing, a first lens, an infrared absorbing filter, an optical filter, and a second lens. The lamp housing includes a lamp and a light-port. In operation, broad spectrum light from the lamp exits the lamp housing by passing through the light-port. The first lens then collimates the broad spectrum light that exits the lamp housing through the light-port. The infrared absorbing filter then passes a first portion of the collimated broad spectrum light to the optical filter and absorbs infrared light of the broad spectrum light. The optical filter then passes a second portion of the collimated broad spectrum light to the second lens. The second lens then disperses the second portion of the collimated light to provide uniform irradiation of a cell culture plate. A method of using the lighting system for studying a photosensitizer is also disclosed.
