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Purpose: To determine, through simulations, the likely validity of Grand-Seiko autorefractors with annular targets in peripheral refraction.Methods: Using a physical model eye, the distance inside the eye to which the Grand Seiko AutoRef/Keratometer WAM-5500 beam was converging and the effective size of its outer diameter at the cornea were determined. Grand-Seiko refraction was calculated from R x = (θ + α)/h 1 , where θ is the angle of the ingoing radiation beam, h 1 is the height of the beam at the anterior cornea and α is the angle of the beam emerging from the eye following reflection at the retina. Two eye models were used: a Navarro schematic eye and a Navarro schematic eye with a contact lens having a highly positive aspheric front surface. Results:The instrument beam was determined to be converging towards the eye to a distance of 24.4 mm behind the corneal vertex, with a 2.46 mm effective size outer diameter of the beam at the anterior cornea. The Grand-Seiko refractions provided accurate estimates of peripheral refraction for the model eyes.The results were closer to Zernike refractions than to Zernike paraxial refraction. Spherical aberration influenced refraction by up to 0.5 D, and peripheral coma had limited influence. Conclusion:Grand-Seiko autorefractors in current use, and having a circular annulus with an ingoing effective outer diameter at the front of the eye of about 2.4 mm, are likely to give valid peripheral refractions.

To study the optical principles and properties of autorefractors that use the image-size principle in which the size of the reimaged retinal image determines refraction. Methods:The retinal illumination and reimaging of the retinal image were described, as were variations in the basic system. Imaging was determined for systems in which the light source is either diverging or converging as it passes into the eye. Equations were determined to describe the dependence of refraction on the heights and angles of incoming and outgoing beams, and refraction error was determined when eye position was not correct. Results:The fundamental refraction equation is D E = ± ( + )∕h 1 where D E is refraction, h 1 is the beam height entering the eye, and θ and α are the angles of the incoming and outgoing beams, respectively. The negative sign outside the brackets applies if the beam focuses before entering the eye, while the positive sign applies if the beam focuses after entering the eye. When light is diverging as

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Holographic Optical Elements (HOE) are well known optical devices which can be used as for example light focusing and/or directing the light to desired areas. Until now, there have been no manufacturing facilities capable to manufacture substantial quantities of volume holographic optical elements with in-application stable properties devoted to being used as taillights or head-up displays in a relatively harsh automotive environment. We describe in this article the working principles of an industrial manufacturing process of holographic optical elements targeting automotive industry needs.