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薄膜真空规是利用金属薄膜的两侧压强差,使薄膜产生应变。在薄膜一侧的附近装有固定电极板。这样在薄膜与固定电极之间构成一电容。当薄膜产生应变时,两者之间的电容发生改变。由电容的改变可测得薄膜两侧的压强差。其示意图如图1所示。其中P。为参考的已知压强,P为待测压强,当P>P。时,d。为薄膜两侧压强相等时薄膜与固定电极之间的距离。锁相放大器测量电容的原理,由锁相放大器的基频调制信
Film vacuum gauge is the use of metal film on both sides of the pressure difference, the film strain. A fixed electrode plate is mounted near one side of the film. This forms a capacitance between the film and the fixed electrode. When the film is strained, the capacitance between the two changes. Changes in capacitance can be measured on both sides of the film pressure difference. The schematic diagram shown in Figure 1. Where P. For the reference of the known pressure, P is the pressure to be measured, when P> P. When, d. Is the distance between the membrane and the fixed electrode when the pressure on both sides of the membrane is equal. Lock-in amplifier capacitance measurement principle, the lock-in amplifier baseband modulation signal