I am setting up a mirror stereoscope for use in psychophysical experiments. The stereoscope will be composed of two beamsplitters equidistant from two computer displays, with the participant sitting in front of the two beamsplitters. I am unsure how to characterize the optical properties of the stereoscope; a picture of the set-up and illustrations of my questions are in the attached image.
A. How do I compute theta, the angular subtense of the display as seen by either eye? Where is the image created?
The next two questions may be ill-posed / illustrations may be incorrect because they depend on where the image is formed.
B. Is the accommodative demand (1 / viewing distance) determined through considering the entire light path (i.e., a + b)? Relatedly, is the demand the same at each point on the mirror because a covaries with b?
C. Vergence demand is created when the lines of sight of both eyes are not parallel with infinity (e.g., lines of sight directed at the dark circle). How do I compute this demand for the image created by the mirrors? What does it mean for the lines of sight to 'not be parallel' with the emergent light?
Think that is a good start for now. Thanks.