Abstract: A signal waveform of an estimation signal and a signal waveform of the reflected light intensity signal are coordinated with each other such that a time point when a film thickness is equal to zero in the signal waveform of the estimation signal and a base point in the signal waveform of the reflected light intensity signal coincide with each other. A film thickness corresponding to that estimated value of a signal intensity of a reflected light which corresponds to a film thickness range corresponding to a time range in the signal waveform of the estimation signal and coincides with the signal intensity of the reflected light at a desired time point is set as a film thickness of a thin film at the desired time point.

Abstract: A signal waveform of an estimation signal and a signal waveform of the reflected light intensity signal are coordinated with each other such that a time point when a film thickness is equal to zero in the signal waveform of the estimation signal and a base point in the signal waveform of the reflected light intensity signal coincide with each other. A film thickness corresponding to that estimated value of a signal intensity of a reflected light which corresponds to a film thickness range corresponding to a time range in the signal waveform of the estimation signal and coincides with the signal intensity of the reflected light at a desired time point is set as a film thickness of a thin film at the desired time point.

Abstract: A gas spring is intended to permanently maintain the sealing performance of a lip in a dust seal without being affected by pressure from a gas sealed inside the spring. A rod body is operates in conjunction with a cylinder body with a gas of a predetermined pressure sealed inside the cylinder body. The rod body is movable into and out of the cylinder body. A rod guide is penetrated by the rod body at a shaft core portion inside a head end portion of the cylinder body. A dust seal has with a lip in sliding contact with an outer circumference of the rod body. A sealed end portion of the cylinder body is in contact with an outer end of the rod guide inside the cylinder body. The dust seal is integrally incorporated at the outer end portion of the rod guide.