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Claim 1

AN OPTICAL SYSTEM FOR AN OSCILLOGRAPH IN WHICH THE TIME BASE DEFLECTION OF A BEAM OF LIGHT ACROSS THE RECORDING SURFACE IS SUBSTANTIALLY CONSTANT COMPRISING: (A) A LINE SOURCE OF LIGHT; (B) A LIGHT BEAM RECORDING SURFACE IN FIXED LIGHT BEAM RECEIVING POSITION; (C) A ROTATABLE GALVANOMETER MIRROR POSITIONED RELATIVE TO SAID LINE SOURCE OF LIGHT AND SAID LIGHT BEAM RECORDING SURFACE SO AS TO DEFLECT THE LIGHT BEAM ACROSS THE RECORDING SURFACE IN RESPONSE TO AND IN PROPORTION TO THE MAGNITUDE OF ELECTRICAL SIGNALS; (D) A ROTATABLE PLANE MIRROR POSITIONED IN THE PATH OF LIGHT BETWEEN SAID GALVANOMETER MIRROR AND SAID RECORDING SURFACE, SAID ROTATABLE PLANE MIRROR BEING ROTATABLE ON AN AXIS AT 90* TO THE AXIS OF ROTATION OF SAID GALVANOMETER MIRROR; (E) A PENDULUM COMPRISING THE DRIVING MEANS FOR THE ROTATABLE PLANE MIRROR AND BEING OPERATIVELY CONNECTED WITH THE ROTATABLE MIRROR SO THAT THE POINT OF MAXIMUM VELOCITY OF ROTATION OF THE PENDULUM, AND HENCE THE POINT OF MAXIMUM SPEED OF ROTATION OF SAID ROTATABLE MIRROR, CORRESPONDS TO THE POINT AT WHICH THE RELATIVE VELOCITY OF MOVEMENT OF THE LIGHT BEAM ALONG THE RECORDING SURFACE WOULD BE LEAST IF THE ROTATABLE MIRROR WERE TO BE ROTATED AT UNIFORM VELOCITY; WHEREBY THE NON-UNIFORM VELOCITY OF ROTATION IMPARTED TO SAID ROTATABLE MIRROR BY SAID PENDULUM COMPENSATES FOR THE NON-UNIFORM MOVEMENT OF THE LIGHT BEAM ALONG THE RECORDING SURFACE THAT WOULD OCCUR AT UNIFORM ROTATION OF SAID MIRROR, THEREBY CAUSING THE LIGHT BEAM TO MOVE AT A UNIFORM VELOCITY ACROSS THE RECORDING SURFACE IN A DIRECTION PERPENDICULAR TO THE DIRECTION IN WHICH THE LIGHT BEAM IS DEFLECTED ON THE RECORDING SURFACE BY THE GALVANOMETER MIRROR.