Device for synchronous modulation, synchronous light-path switch-over and control-signal derivation for step-drive controlled modulation and switch-over devices

Claim 1

In a device for synchronous modulation, synchronous light-path switch-over and control signal derivation for step-drive controlled modulation and switch-over devices, in which light modulation is effected via a rotating light stop and the light path switch-over between a measuring beam and a reference beam is effected by pivoting mirrors, the improvement wherein a single sensor is optically coupled to the output of the modulation light stop for deriving a synchronization signal, the synchronization signal is applied to a threshold switch for digitalization the output of the switch is applied to a frequency divider, the output of the divider is applied to a multiplexer and thence to a first pulse shortening stage for positive and negative slopes for application to the reset input of a counter, means clocking the counter at a clock frequency, means applying the output of the threshold switch via a first adjustable timing device ot a second adjustable timing device, the output of the second timing device comprising a control signal for demodulation, the output of the counter being connected to a logic circuit for generating a specified number of pulses as well as to second and third pulse shortening stages, the outputs of the second and third pulse shortening stages being connected to the set inputs of stepping motor triggering circuit means, the output of the logic circuit being connected via a gate circuit to the inputs of the stepping motor triggering circuit means, means applying the synchronization signal to the first input of the motor triggering circuit means, the output of the stepping motor triggering circuit means being connected to directional inputs of step-drive selection circuits of the light path switch-over device, and further comprising mechanical stops for limiting the motion of the switch-over device during the synchronization process at the pivoting mirrors of the switch-over device.