A first semiconductor laser emits a light beam L1 with a first wavelength polarized in an x-axis direction. One exemplary moisture detection assembly includes a moisture-absorbent sensor element and an indicator. The user conveniently grips the housing to apply the requisite force to remove the pin from the bridge of the guitar. In addition, a carbon-based thin film is placed on a film containing an organic compound, so that it prevents the electric filed from being locally concentrated and also prevents the generation of short-circuit between the anode and the cathode. A flow of air is delivering through each nozzle sufficient to remove the excess coating from the excess coating site.