An optical frequency comb generator includes an oscillator for oscillating modulating signals of a preset frequency, and an optical resonator formed by an incident side reflecting mirror and an outgoing side reflecting mirror, arranged parallel to each other. The modification indicator for the metadata can further be displayed to provide version information for the metadata to a user. The layers include a plurality of passive electrical components, such as capacitors, inductors, and resistors, and routing lines. The image may be filtered to decrease diffuse reflectivity.