Fig. 1. Virtual image view distance in augmented reality optical systems

Fig. 2. Change in depth of field caused by changing camera focus position during photographing a virtual image. (a) Relative sharpness curve; (b) focusing at position a; (c) focusing at position b; (d) focusing at position c

Fig. 3. Experimental setup of the test system. (a) Virtual image detection light path; (b) reference object detection light path

Fig. 4. Test pattern used in the measurement method. (a) Input image displayed by AR device; (b) pattern on the reference object

Fig. 5. Flow of the analysis algorithm used to calculate the relative change in sharpness of the shooting image.(a) Experiment image; (b) ROI after pre-processing; (c) e-SFR calculation data; (d) schematic diagram of the relationship between relative sharpness and the focus position of the camera or the object distance of the reference object

Fig. 6. General flow of the virtual image viewing distance measurement. (a) Virtual image photography; (b) virtual image algorithm analysis; (c) reference object photography; (d) reference object image algorithm analysis

Fig. 7. Relative change in sharpness of the AR virtual image with change in focus position. (a) Test 1; (b) test 2; (c) test 3

Fig. 8. Depth of field distribution of the camera system at the corresponding focus positions. (a) Test 1; (b) test 2; (c) test 3