Design constraints and feasibility of holographic optical lenses for vision correction

Developing a Holographic Optical Lens (HOL) for vision correction requires considering specific design limitations. Primary considerations include; achieving a sufficiently wide angular acceptance, maximising the HOL diffraction efficiency, operating as a volume holographic element producing a single order, and determining if the chromatic aberrations remain within tolerable limits for the human eye. HOLs have been developed for numerous applications, and monofocal holographic hybrid refractive lenses have been proposed previously. Off-axis gratings were modelled to evaluate the HOL design. The off-axis angle was calculated as the resultant angle informed by available wrap and pantoscopic tilt angles. The model investigated focal power ranging from +0.5 to +6.0 D in increments of +0.5 D and provided HOL parameters, which were assessed against the feasibility criteria chosen. The feasibility criteria include thicknesses between 10 and 200 μm, a Q and ρ value ≥ 10, a refractive index modulation < 0.03, a full-width at half-maximum of the Bragg curve > 3.4°, and axial chromatic aberration > -2.1 D and transverse chromatic aberration > -3.5 arcmin. Modelling demonstrated that no viable designs met these constraints with off-axis angles < 17°. As these angles increase, a range of powers are recordable, with the maximum power being 3.0 D using an off-axis angle of 19.8°. These findings demonstrate that producing HOLs for vision correction is possible, albeit with significant challenges involved.