1. An apparatus for measuring the ocular gaze points of regard and fixation durations and binocular convergence point of a viewer, comprising: a) a headset; b) a position and orientation sensor having an electrical output, wherein said sensor is constructed so as to connect to said headset, said position and orientation sensor comprising means to determine position and orientation of said headset on head of said viewer; c) an optical unit constructed so as to provide a clocked raster-scan pulse electrical output and further constructed so as to provide a clocked display field refresh pulse electrical output having an optical output, said optical unit is constructed so as to connect to said headset so as to display a visual image onto eyes of said viewer, and further constructed so as to optically output cornea and pupil reflections of the viewer's eyes; d) an opto-electronic device constructed so as to receive an optical input, said optical input connected to said optical output of said optical unit, said opto-electronic device further constructed so as to receive a clocked raster scan pulse electrical input from said optical unit, said opto-electronic device further constructed so as to provide an analog electrical output, said opto-electronic device further constructed so as to provide a digital electrical output for transmitting an electrical signal said opto-electronic device further comprising means for electronically representing spatially optical corneal reflection transmitted from said optical unit; e) a digital processor constructed so as to receive a clocked raster-scan pulse electrical input from said optical unit, said digital processor further constructed so as to receive an electrical digital input, said electrical digital input connected to the digital output from said opto-electronic device, said processor further constructed to read an output from said opto-electronic device on each clock-pulse and further constructed to write said output from said opto-electronic device to a double-buffered digital memory; f) an image processor constructed so as to receive an electrical analog input, said electrical analog input connected to said analog output of said opto-electronic device, said image processor further constructed so as to receive a clocked display field refresh pulse input from said optical unit, said image processor further constructed so as to provide a memory mapped digital output of pupil image coordinates and principal axes following each of a clocked field refresh pulse; g) a digital computer, constructed so as to receive an input connected to the output of said position and orientation sensor, said digital computer comprising means to access an output of said double-buffered digital memory of said digital processor, said digital computer constructed so as to access the memory mapped output of said image processor, said digital computer further constructed so as to receive a clocked display field refresh pulse input, said digital computer further constructed so as to provide a digital output for each of calibration, computed gaze points of regard and fixation durations, and binocular convergence point of the viewer, following said each clocked field refresh pulse, during application.