Security system, particularly for valuable documents

Security system for a security document, said security system comprising:

• a flat security element in a carrier plane that under incident light holographically reconstructs outside the carrier plane a pattern in which concealed information is stored, and
• a flat at least partly transparent verification element which on flat contact with the security element makes the information stored therein readable,
• wherein the security element comprises a first hologram carrier which under incident light reconstructs outside the carrier plane a first pattern in which the concealed information is stored as a phase modulation such that the phase of light in the region of the concealed information is different than the phase of surrounding regions of the pattern, and
• the verification element is configured such that it converts the phase modulation into a visible amplitude modulation.