604 Appendix B 



six points are called the cardinal points. This conclusion is not restricted 

 to two surfaces. Because Equation 26 is identical in form to Equation 9, 

 one can consider two surfaces separating media of different indices of 

 refraction as equivalent to only one surface. This surface can be 

 combined mathematically with a third surface, provided the latter can 

 be approximated by a small section of a sphere whose center lies on the 

 optic axis of the first two. This argument then may be generalized to 

 any number N of surfaces separating media of different indices of 

 refraction, provided the surfaces can all be approximated by small 

 sections of spheres, all of which have a common line of centers. These 

 six cardinal points are used in Chapter 2 to describe the refraction of 

 light in the eye. 



REFERENCES 



1. Stuhlman, Otto, Jr., An Introduction to Biophysics (New York: John Wiley & 

 Sons, Inc., 1943). 



2. Ogle, K. N., Optics: An Introduction for Ophthalmologists (Springfield, Illinois: 

 Charles C. Thomas, 1961). 



3. Glasser, Otto, ed., Medical Physics (Chicago, Illinois: Year Book Publishers, 

 Inc., 1944) Vol. 1. 



a. Luckiesh, Matthew, and F. K. Moss, "Light, Vision and Seeing," 

 pp. 672-684. 



b. Sheard, Charles, "Optics: Ophthalmic, With Applications to Physio- 

 logic Optics," pp. 830-869. 



For a more thorough discussion of optics at an intermediate physics level, 

 see: 



4. Robertson, J. K., Introduction to Physical Optics 2nd ed. (New York: D. Van 

 Nostrand Company, Inc., 1935). 



