A \u201chigh availability\u201d system comprises multiple switches under the control of a control processor. An alternate configuration of a comb-based spectrometer for rapid, high resolution, high accuracy measurements of an arbitrary cw waveform. A refractive material layer is provided at a side of the light-transmissive electrode layer not facing the functional layer. A security office is used to, a key management device and a privilege management device. Moreover, the recording also can stops if a servo error is detected, and the data restart to encode and record from the data block where the recording stops or at least one data block preceding the data block where the recording stops.