METHOD AND APPARATUS FOR PREPARING DISK SUBSTRATE FOR RECORDING OPTICAL INFORMATION

PURPOSE:To obtain an optical information recording disk substrate excellent in a transfer property and free from optical strain, by applying ultrasonic vibration to the central part and outer peripheral part of a cavity in a process wherein a high-molecular substance is begins to be injected in the cavity to take out a product. CONSTITUTION:Molds 2, 3 are integrally combined and a high-molecular substance is injected from an injection machine to fill a cavity with the molten high-molecular substance through a gate 7. The high-molecular substance is solidified by cooling the molds 2, 3 and a product is taken out by dividing the molds 2, 3. When the high-molecular substance is injected while ultrasonic vibration is applied to movable cores 8, 9, not only the orientation in the flow direction of the high-molecular substance is disturbed but also the temp. of said substance rises by the energy of ultrasonic vibration and the flowability of the high-molecular substance becomes large not only to enhance the transfer property of said substance but also to reduce the optical strain thereof. Further, the movable cores 8, 9 can be set to the side of the stamper 4.