Plate inspection system and plate inspection method

A plate inspection method for inspecting a plate by the use of an inspection system for use in the inspection of a plate composed of a color filter having a retardation layer and color pixels of at least one of red, green and blue, the system comprising a polarized-light source for irradiating a polarized light and an observation-side polarizer placed on the observation side,

• the method comprising:
• a placement step of placing a plate to be inspected between the polarized-light source and the observation-side polarizer so that the plate to be inspected is irradiated with polarized light from the polarized-light source, and
• a inspection step of inspecting the plate to be inspected by observing the plate to be inspected through the observation-side polarizer while changing the position of at least the observation-side polarizer or the plate to be inspected relative to the polarized-light source,
• wherein the wavelength of the polarized light from the polarized-light source is substantially the same as the wavelength at which the transmittance of light passing through the color pixels reaches a maximum.