Chapter 1. Vision System Design

Chapter 2. Biological Eye Designs
A. Camera
B. Pinhole
C. Concave mirror
D. Apposition
E. Neural
superposition
F. Refraction
superposition
G. Reflection
superposition
H. Parabolic
superposition
I. Multiple sensor 
types and 
combinations of types

Chapter 3. Eye 
Design Illustrations

Chapter 4. Eye 
 Reproduction

Chapter 5. Optical 
 Systems Design 

Chapter 6. The Eye Designer

Related Links

Appendix A - Slide Show & Conference Speech by Curt Deckert

Appendix B - Conference Speech by Curt Deckert

Appendix C - Comments From Our Readers

Appendix D - Panicked Evolutionists: The Stephen Meyer Controversy

 
 
 
 
 
 
 
 

EYE DESIGN BOOK
Chapter 2
Sections G, H and I
- Prev Page           Go to Chapter Links -            Next Page - 

(Click on PICTURE IN TEXT to bring up LARGE PICTURE)

 2. BIOLOGICAL EYE DESIGN 
G. Reflecting superposition compound
     In a reflection superposition eye optical design, a number of reflective, instead of refractive light pipe, lens elements work together to form an image on a series of image receptors constructed like a small retina. Here initial optical elements are reflectors rather than transmitters like eyeglasses. A small number of the total reflective surfaces are used to form each small increment of an image. 

Light is reflected off the sides of small internal facets to focus images on a small group of sensors. Typical creatures with this optical design include some shrimp and crayfish. The optical design is quite similar to other superposition designs. Figure 2.16 illustrates the reflective superposition optical design Figure 2.17 shows an example of reflective superposition eyes. (p. 303, Fig. 3d, Vision Optics Evolution by Dan E. Nilsson, Biosciences, Vol. 39, No. 5, May 1989)

Figure 2.16. Reflective  Superposition Optical Design (Like Fig. 6-7)

Because of the sharp corners, the internal registration and precision of the reflective surfaces seem to be more critical than previous compound eye designs. This design could work with a wide variety of color combinations, including UV and IR. This optical approach allows design flexibility in creatures where the optical system has more room for a compact retina-type sensor array. Image processing is still difficult to accomplish in the very small volume available for brains in the small creatures using this optical design. (P. 482, Apposition and Superposition Eyess, Peter Kunga, Photochemistry of Vision, Ed. by H. J. A. Dartnall, Sprinzer-Verlag, N. Y., Germany, 1972)

Figure 2.17. Example  of Reflective-Superposition  Eyes of a Crayfish  (Cross Section)

H. Parabolic superposition compound 

In the parabolic superposition compound eye design, the parabolic surfaces of the inside of each facet focus light from a reflector to a sensor array. Parabolic reflective facet surfaces work together like arrays of lenses to produce an image on a group of receptors, like a small retina. This form of facet design uses refractive lenses in addition to reflective parabolic surfaces. Each facet acts something like a Galilean telescope. (p. 303, Fig. 3e, Vision Optics & Evolution by Dan E. Nilsson, BioSciences, Vol. 39, No. 5, May 1989)

Figure 2.18 Parabolic  Superposition Optical  Design (Like Fig. 6-8)

Can one conceive how an array of micro-telescopes originated within crab eyes? 

Image processing is still difficult, but this type of design can offer increased durability. Part of this short-focus optical design is somewhat similar to reflective x-ray imaging optics. Figure 2.18 above illustrates the parabolic superposition optical design. Figure 2.19 shows an example of parabolic superposition eyes. (P. 91 middle, Readers Digest, Exploring the Secrets of Nature, 1994)

Fig 2.19 Example of Parabolic Superposition  Eyes of a Hermit Crab (Like Fig. 3-8)

One variation of this elegant design occurs in some mayflies. It seems complicated for use in animals that seem to have a relatively simple short-term role. They are shown on Figure 2.20. (P. 153 top right, Readers Digest, Exploring the Secrets of Nature, 1994)       The evidence of intelligent design is again apparent in this optical design and in the way it is distinguished from other similar optical designs.

Figure 2.20 Example of Parabolic  Superposition Eyes of a Mayfly

      The following tables give some idea as to the wide variety of Animal Eye Resolution (Figure 2-20a) Sensitivity (Figure 2-20b).

Figure 2-20a Eye Resolution (Ref table 3.1, p. 38, Animal Eyes, Michael F. Land, Dan-Eric Nilsson, Oxford Animal Biology series, Oxford University Press, 2002)

Figure 2-20b Eye Sensitivity (Reference table 3.2, p. 52, Animal Eyes, Michael F. Land, Dan-Eric Nilsson, Oxford Animal Biology series, Oxford University Press, 2002- Please see their book for more details )

I. Multiple sensor types and combinations of types
     Several animals have specific receptor eyes and distributed eyes to supplement their main eyes. This type of vision occurs in some crabs and shrimp, and in other animals that have several types of eyes working together. These combinations cause us to ask new questions.
     Does any creature have control of how many facets they can produce? 
     Why wasn't this multiple vision technique used more widely?
     To answer these and related questions we need to consider the make up of the cellar building blocks with the biochemical requirements for each cell. For example, eye materials become important as we consider different pigments for different spectral regions. Lenses are also made up of different materials, some of which have critical distributions of cells made up of many different materials. Even the periodic table describing the elements is evidence of design beyond the molecular level in that available elements have something to do with the colors eyes are able to see.
     Irreducible vision functions have been determined for many different working vision systems. Here we considered eye optics, cells, and the DNA directing the biochemical process at the cellular level. 

     The following section will focus on specific examples of biological optical design applications. We will consider a few examples of the amazing eyes from each of the major design types.