OPTICS Eye optical system 1. Optical power of the cornea: П2-П1 Пз-п2 Fcornea = F1 + F2 = R1 Ciliary fibers R2 F - optical power of the cornea front surface, D; F, - optical power of the cornea back surface, D; R1 radius of curvature of the cornea front surface, m; Iris Cornea Vitreous humor Lens R, – radius of curvature of the cornea back surface, Fovea m; n1 – ambient refraction index (for air n, = 1 and for water n = 1.33); n2 – cornea refraction index; n3 – aqueous humour refraction index. 2. Optical power of the crystalline lens: N5-N4 R4 Optic nerve Aqueous humor Retina па-пз Fcrystalline lens = F3 + F4 = R3 Sclera F3 - optical power of the crystalline lens front surface, D; F4 – optical power of the crystalline lens back surface, D; R3 - radius of curvature of the crystalline lens front surface, m; R4 – radius of curvature of the crystalline lens back surface, m; n3 - aqueous humour refraction index; n4 – crystalline lens refraction index; ng – vitreous humor refraction index. Table - Parameters for the Eye Radius, mm Back Index of Front refraction R2 = 7.3 R4max = 6 R4min = 5.5 Cornea R, = 7.8 n2 =1.38 Crystalline lens (Fmin) Crystalline lens (Fmax) R3max =10 R3min = 6 Aqueous humour and vitreous humor N4 =1.4 Пз 3 n5 =1.33 3. Optical power of eye: F= Fcornea + Fcristalline lens 4. Lens equation: Ri Cornea Lens R: = -+- Rs R. f f– lens focal length (m); F – lens optical power (D); p - distance from the object to the lens or object distance (m); q – distance from the image to the lens or image distance (m). 5. Height of image on the retina: h•q Н%— H – height of image on the retina, m; h – height of object, m; q – image distance (for human eye on the average is equal to 1.5 cm), m; p – distance of the object to optical system of the eye, m. 6. Lens magnification: Н M H – image height (m); h – object height (m), p – object distance (m); q – image distance (m). 7. Law of refraction: n1 sino, = n2sin02 1 OPTICS n. is refraction index of the first medium n. is refraction index of the second medium A. 3. (a) Using table data presented in the text, calculate the focusing power Fmax of the crystalline lens in the case when eye is focused to view objects located at near point of the eye. (b) Knowing that focusing power of the cornea is Fcornea = 42 D, calculate maximum focusing power of the eye. (c) Find what if the eye focal length in this case.