| 摘要 |
In a system for measuring the pressure of a gas sealed in a lamp, a laser beam emitted from a laser unit and converged by a convergent lamp is split by a first half mirror into first and second laser beams. The first laser beam is focused to a focal point of the lens close to the filament of the lamp, diverged from this focal point, and reflected by a first mirror toward a second half mirror. The second laser beam is reflected by a mirror toward the second half mirror. At the second half mirror, both laser beams are combined and converted into interfered light. The interfered light is projected to an aperture which transmits the light rays within half fringe of interference. The light rays become incident on a photodetector. When the lamp is energized, the interference fringes change during a predetermined period of time, and signals of light and dark levels are alternately detected by the photodetector. The signals output by the photodetector are processed during a predetermined period of time. On the basis of the interference order data obtained, the gas pressure inside the lamp is calculated according to a predetermined equation.
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