A hermetically sealed pressure switch apparatus and method includes a metal bellows directly installed at an inlet port for providing hermetic sealing thereof. The method programs a nonvolatile variable resistance element including a variable resistance layer, which changes between a high resistance state and a low resistance state depending on a polarity of an applied electric pulse, and a lower electrode and an upper electrode. The first array of optical fibers is configured to transmit a pattern of light towards a test object and the pattern of light is configured to cause sound waves in the test object when the pattern of light encounters the test object.