A haploscope is an optical system which produces a carefully controlled virtual image. Since the development of Wheatstone's original stereoscope in 1838, haploscopes have been used to measure perceptual properties of human stereoscopic vision. This paper presents an augmented reality (AR) haploscope, which allows the viewing of virtual objects superimposed against the real world. Our lab has used generations of this device to make a careful series of perceptual measurements of AR phenomena, which have been described in publications over the previous 8 years. This paper systematically describes the design, assembly, calibration, and measurement of our AR haploscope. These methods have been developed and improved in our lab over the past 10 years. Despite the fact that 180 years have elapsed since the original report of Wheatstone's stereoscope, we have not previously found a paper that describes these kinds of details.

For optical see-through head-mounted displays, the mismatch between a display's focal length and the real world scene inadvertently prevents users from simultaneously focusing on the presented virtual content and the scene. It has been shown that it is possible to ameliorate the out-of-focus blur for images with a known focus distance, by applying an algorithm called Sharp View. However, it remains unclear if Sharp View also improves the readability and clarity of text rendered on the display. In this study, we investigate whether users reported increased text clarity when Sharp View was applied to a text label, and how the focal demand of the display, the focal distance to real world content, and gaze condition affect the result. Our results indicate that, in non-fixated viewing, there is a significant user preference for Sharp View-enhanced text strings.