Design of Off-Axis Head-Mounted Display Optical System Based on Two Reflective Optical Free-Form Surfaces

Jingfei Ye; Kaidi Xu; Mingzhu Yang; Zhenzhen Song; Shixin Pei; Lingbing Bu; Lu Chen; Zhishan Gao; Jun Yu; Zhengxiang Shen

doi:10.3788/AOS201838.0722003

Journals >Acta Optica Sinica >Volume 38 >Issue 7 >Page 0722003 > Article

Acta Optica Sinica
Vol. 38, Issue 7, 0722003 (2018)

Design of Off-Axis Head-Mounted Display Optical System Based on Two Reflective Optical Free-Form Surfaces

Jingfei Ye^1、*, Kaidi Xu¹, Mingzhu Yang¹, Zhenzhen Song¹, Shixin Pei¹, Lingbing Bu¹, Lu Chen², Zhishan Gao², Jun Yu³, and Zhengxiang Shen³

Author Affiliations

¹ School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing, Jiangsu 210044, China

² School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China

³ School of Physics Science and Engineering, Tongji University, Shanghai 200092, China

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DOI: 10.3788/AOS201838.0722003 Cite this Article Set citation alerts

Jingfei Ye, Kaidi Xu, Mingzhu Yang, Zhenzhen Song, Shixin Pei, Lingbing Bu, Lu Chen, Zhishan Gao, Jun Yu, Zhengxiang Shen. Design of Off-Axis Head-Mounted Display Optical System Based on Two Reflective Optical Free-Form Surfaces[J]. Acta Optica Sinica, 2018, 38(7): 0722003 Copy Citation Text

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Fig. 1. Optical configuration of off-axis two mirror head-mounted display system

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Fig. 2. Distributions of (a) system focal length and (b) full field of view at different exit pupils and F numbers

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Fig. 3. Design of off-axis head-mounted display optical system based on two reflective free-form surfaces

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Fig. 4. MTF curves of off-axis head-mounted display optical system based on two reflective free-form surfaces in different fields

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Fig. 5. Distortion curves of off-axis head-mounted display optical system based on two reflective freeform surfaces

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Fig. 6. Local sag maps of optical freeform surfaces of the off-axis reflective head-mounted display optical system. (a) Anamorphic free-form surface (the first freeform mirror); (b) XY polynomial freeform surface (the second free-form mirror)

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Year	2007^[5]	2010^[17]	2009^[7]	2010^[8]	2014^[13]	2014^[12]
Design result
Exit pupil /mm	8	3	8	15	≈5	8
EFL /mm	≈30	14.25	15	28.74	≈23	30
F#	≈3.75	4.75	1.875	≈1.9	≈4.6	3.75
FOV	20°16(H)×12(V)	≈24°19(H)×14.5(V)	53.5°45(H)×32(V)	50°40(H)×30(V)	≈25°21(H)×12.4(V)	30°24(H)×17(V)
Eye relief /mm	15	>15	>17(18.25)	>60(70)	>15(≈17)	15
MTF value	>20%@35 lp·mm^-1within central3 mm pupil	>10%@35 lp·mm^-1for all fieldswithin all pupil	>10%@30 lp·mm^-1within central3 mm pupil	>30%@30 lp·mm^-1for all fieldswithin all pupil	>10%@50 lp·mm^-1within central3 mm pupil	>40%@30 lp·mm^-1within central4 mm pupil
Display size	0.44 inch	4.8 mm×3.6 mm	0.61 inch	0.61 inch	8.5 mm×5 mm	0.61 inch
Structure	XY polynomialreflector anddiffractiveelement	Radial basisfunction basedfreeformreflector	XY-typepolynomialsurface withfreeform prism	Including XYpolynomialfreeformsurface	Zernikepolynomialfreeformreflector	XY polynomialfreeformreflector
Weight /g	≈250	much light	8	heavy	much light	much light
Note: EFL is effective focal length; FOV is field of view; MTF is modulation transfer function; 1 inch=2.54 cm.

Table 1. Comparison of design parameters of several different free-form head-mounted display optical systems

Parameter	Design 1^[13]	Design 2^[12]	Our design
Exit pupil /mm	≈5	8	10
EFL /mm	≈23	30	30
F#	≈4.6	3.75	3.0
FOV /(°)	≈25	30	28
Eye relief /mm	≈17	15	>15
MTF	>0.1 @50 lp·mm^-1within central 3 mm pupil	>0.4 @30 lp·mm^-1within central 4 mm pupil	>0.15 @30 lp·mm^-1within central 6 mm pupil
Distortion /%	<6.2	<3.5	<4.5
Display size	8.5 mm×5 mm850×50010 μm·pixel^-1	12.75 mm×9 mm800×60015 μm·pixel^-1	12.6 mm×9 mm800×60015 μm·pixel^-1
Surface type	Zernike polynomialfreeform surface	XY polynomialfreeform surface	Anamorphic+XYpolynomial freeform surface

Table 2. Comparison of different design results of off-axis reflective head-mounted display optical systems

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