A piezoelectric lighter includes a lighter casing, an ignition nozzle, a gas releasing valve, a piezoelectric unit, and a hidden push button arrangement. The filter assembly includes a filter body, a filter mounted on the filter body, and a spring-loaded coupling member moveable relative to the filter body for engaging the duct. The threads on the male and female threads, bodies are provided in an interrupted-thread pattern, allowing the male body to be completely inserted into the female body before twisting and engaging the threads. Therefore, even if there is any deviation along the p- or s-polarization axis of the amplitude equivalent value measured by the first measuring section, the group delay times are determined on the basis of the results of measurement by the second measuring section. The raster arrangement is configured to be used in a microlithography illumination system. Accordingly, the large capacity memory module can be advantageously mounted to the portable terminal and an electromagnetic field can be effectively shielded.