In a high density spiral track-forming apparatus which forms a spiral-shaped recording track on a disk-shaped substrate disk by focusing the recording beam on the surface of the disk-shape substrate disk while moving the optical recording system in the radial direction of the rotating disk-shape substrate disk, an optical recording system transferring device, comprising:
- (i) means for transferring the optical recording system in the radial direction of the substrate disk;
- (ii) means for detecting the travel velocity of the optical recording system, said travel velocity detecting means having,
- (a) length measuring means for measuring the distance traveled of the optical recording system in the radial direction of the substrate disk and for generating a traveled distance equal corresponding thereto, and
- (b) velocity computing means for computing the travel velocity of the optical recording system according to the optical recording system traveled distance signal from the length measuring means and the time elapsed during said distance traveled, and for generating a travel velocity signal corresponding to said computed travel velocity;
- (iii) means for setting a target velocity value for the optical recording system and for generating a target velocity signal corresponding thereto;
- (iv) means for comparing the travel velocity signal from said travel velocity detecting means with the target velocity signal from said target velocity setting means;
- (v) means for controlling said optical recording system transferring means so that the travel velocity of the optical recording system becomes equivalent to the target velocity;
- (vi) where said length measuring means comprises a laser length measuring device;
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- (vii) said velocity computing device comprises a trigger circuit for outputting sampling signals with a fixed sampling period, a gate circuit for inputting a positional signal from the optical recording system from the laser length measuring device in accordance with the sampling signal from the trigger circuit, a delaying device for delaying the positional signal from the gate circuit by a time equal to one sampling period, a first memory device for registering the delayed positional signal from the delaying device, a second memory device for registering a subsequent positional signal from the gate circuit, a comparator for comparing the positional signal from the first memory device and the subsequent positional signal from the second memory device to compute their difference, and a multiplier for outputting the result of multiplication obtained by multiplying the signal for the distance traveled sent from the comparator by the inverse of the sampling time.