A pneumatic micrometer, developed to apply as a linear deflection type meter, is described. This is based on the measuring system of both a cascade connected pneumatic amplifier, composed of two pneumatic amplifier units with a high pressure supply, and a linear feedback transducer. The transducer is constructed from a set of two bellows and an elastic plate which has a rectangular crosssection, and the measuring range of the meter can be changed by the selection of the effective area of the bellows of the transducer.
Since the position of the gauging nozzle of both the input and output stage is finely adjustable, the amplification and the measuring force of the device can be widely selected by adjusting them. The performance of this device is shown as follows; measuring range: 12, 60μ, output level: 0.6kg/cm² (linearity 1%) gauging force: 0.4∼0.5g, responce time: 3∼4sec (95% settling time) loading volume: 1000cm³). Applications are also described on surface waviness measurement and use as a comparator using a pair of the measuring system.