Abstract: An evoked potential autorefractometry system includes a computer driving an alternating checkerboard mirror stimulus to project a stimulus pattern directly to a patient through a continuously variable focus lens controlled by the computer and which maintains a constant image size on the patient's retina. The evoked potentials produced by the patient are amplified, asychronously filtered both in an analog and digital fashion to allow peak to peak detection of the evoked potentials to determine amplitude. The digital filter includes a 255 point running sum. The peak to peak amplitudes are asychronously digitally filtered using a 16 point running sum to produce an amplitude measure of the evoked potentials. The lens is swept rapidly from one extreme of focus to the other extreme in relatively large steps to determine the area in which the peak amplitude occurs.

Abstract: A self-preparing subkeratinous probe for electroencephalographic measurement includes a spring body which applies a penetrating force to a plow which parts hair and scrapes through a dead keratinous layer of skin to a bloodrich epidermis layer while the probe is being positioned on the head without causing bleeding. The plow includes tabs which form a gap for parting the hair and scraping the skin. The probe also includes an electrolyte tube which can be used to apply electrolyte solution to the skin and plow after it is positioned.