Abstract: In a process for metal replication of Glass dies, the cleaned die is secured in a cavity of a fixture, and a thin masking diaphragm is placed over the die and fixture to expose only the die surface to be replicated. A vacuum is applied through passages in the fixture to secure the diaphragm. The diaphragm-die surface is silvered to render it conductive, and the fixture is immersed in an electroplating bath. After sufficient buildup of electrodeposited material, the fixture is removed from the bath. The metal replica is then removed from the die to reveal a surface which includes an exact replica of the glass die master.

Abstract: A device for objectively determining visual acuity includes a viewing screen on which a moving spot of light of diminishing intensity is projected. Infrared eye tracking sensors scan the eyes of the subject and generate a voltage analog signal of the eyes' position. The position signal is compared with a signal representing the position of the moving spot, and the difference is fed to a threshold detector circuit. As the spot becomes too dim to be seen by the subject, the eyes fail to track the spot, and the difference between the two signals surpasses the threshold of the detector circuit. The brightness of the spot when last tracked successfully, which correlates with standard visual acuity measurements, is then displayed as the visual acuity of the subject.