Abstract
This Paper describes a method of determining the deflection of the beam in a precision balance. The inclination of the beam at balancing point is usually evaluated by observing successive turning-points of the beam oscillation. To make automatic and digital readout of the beam deflections, a specially designed grating scale and a photoelectric sensor are incorporated in the scale-mirror optical magnifying system. Output signals of the sensor corresponding to respective graduations at every turning are counted.
The advantage of the method is as follows:
(1) Turning-point readings can be taken without maximum points of the deflection.
(2) A number of observations over a time can be taken automatically.
The experiments show that one count of the pulse corresponding to one division of 0.1mm on the scale or to the deflection angle of 1.3×10-5rad is readily detectable with a reasonably small S/N ratio of photoelectric output.
By reading the pulse signals of the photoelectric output on the chart of an electric recorder, a high precision of 2×10-6rad is attained.
