We report on small student (high school) project of the Czech Academy of Sciences dealing with animal (fish) eyes and possible application in science and technology. Albeit most fishes have refractive eyes, the recent discoveries confirm that some fishes have reflective eyes with strange arrangements as well

Hudec R.

Michalova S.

Contributions of the Astronomical Observatory Skalnaté Pleso

English

We report on small student (high-school) project of the Czech Academy of Sciences dealing with animal (fish) eyes and possible application in science and technology. Albeit most fishes have refractive eyes, the recent discoveries confirm that some fishes have reflective eyes with strange arrangements as well

Kazan Federal University Digital Repository

Contributions of the Astronomical Observatory Skalnate Pleso 2017 vol.47 N2, pages 94-99Fish eye opticsHudec R., Michalova S.Kazan Federal University, 420008, Kremlevskaya 18, Kazan, RussiaAbstractWe report on small student (high-school) project of the Czech Academy of Sciences dealing withanimal (fish) eyes and possible application in science and technology. Albeit most fishes haverefractive eyes,  the recent  discoveries  confirm that  some fishes have reflective eyes withstrange arrangements as well.KeywordsAnimal Eyes, Biomimetics, Fish-Eye Optics, Lobster eye optics, X-ray monitoringReferences[1] Angel, J. R. P. 1979, Astrophys. J., 233, 364[2] Baca, T., Platkevic, M., Jakubek, J., et al. 2016, Journal of Instrumentation, 11, C10007[3] Hudec, R., Pina, L., Inneman, A., & Tichy, V. 2015, in Proceedings of the SPIE, Vol. 9510, EUV and X-ray Optics:Synergy between Laboratory and Space IV, 95100A[4] Hudec, R. & Remisova, K. 2016, Application of Biomimetics Principles in Space Optics, ICSO2016 Proceedingsavailable online at http://www.icsoproceedings.org/[5] Land, M. 1965, The Journal of Physiology[6] Land, M. 1972, Progress in Biophysics and Molecular Biology[7] Land, M. 1976, Nature[8] Partidge, M. e. a. 2014, Proceedings. Biological sciences/The Royal Society[9] Pina, L., Burrows, D., Cash, W., et al. 2014, in Proceedings of the SPIE, Vol. 9207, Advances in X-Ray/EUV Opticsand Components IX, 92070T[10] Pina, L., Hudec, R., Inneman, A., et al. 2015, in Proceedings of the SPIE, Vol. 9510, EUV and X-ray Optics:Synergy between Laboratory and Space IV, 951005[11] Pína, L., Hudec, R., Inneman, A. J., et al. 2016, in Proceedings of the SPIE, Vol. 9964, Advances in Laboratory-based X-Ray Sources, Optics, and Applications V, 99640B[12] Remisova, K. 2016, Physiology of special mirror eyes of molluscs, crustaceans and deep-sea fish[13] Schmidt, W. K. H. 1975, Nuclear Instruments and Methods, 127, 285[14] Urban, M., Nentvich, O., Stehlikova, V., et al. 2016, submitted to Acta Astronautica[15] Wagner, H., Douglas, R., Frank, T., Roberts, N., & Partridge, J. 2014, Current Biology, 108

Fish eye optics

Digital Library of the Czech Technical University in Prague

Contrib. Astron. Obs. Skalnate´ Pleso 47, 94 – 99, (2017)Fish eye opticsR.Hudec1,2,3 and S.Michalova2,41 Czech Technical University in Prague, Faculty of Electrical EngineeringTechnicka 2, Prague 166 27, Czech Republic(E-mail: hudecren@fel.cvut.cz)2 Astronomical Institute of the Czech Academy of Sciences, Ondrejov, CzechRepublic3 Kazan Federal University, Russian Federation4 Dvorakovo Gymnazium, Kralupy n. Vlt., Czech RepublicReceived: May 26, 2017; Accepted: June 28, 2017Abstract. We report on small student (high–school) project of the CzechAcademy of Sciences dealing with animal (fish) eyes and possible applicationin science and technology. Albeit most fishes have refractive eyes, the recentdiscoveries confirm that some fishes have reflective eyes with strange arrange-ments as well.Key words: Fish–Eye Optics – Animal Eyes – Lobster eye optics – X-raymonitoring– Biomimetics1. IntroductionPrinciples of some animal eyes were succesfully applied in space optics in the pastand recently, e.g. in Lobster-Eye optical systems, e.g. (Hudec et al., 2015; P´ınaet al., 2016). However, the recent growing knowledge of sea vision, especiallydeep sea fishes, makes possible to consider other such applications.Albeit most fishes have refractive eyes with spherical lens, there are new dis-coveries e.g. is deep sea fish Rhynchohyalus natalensis with mirror eyes based onvery large numbers of very small mirrors developed from the choroidal argenteawith crystals orienteted almost parallel to the mirrors surface. This arrangementmay even include principles of multi–mirror active optics (Hudec & Remisova,2016; Remisova, 2016).We report on ongoing study with focus on understanding of very specificeyes of sea animals and how they may help us to design and develop specialoptics for scientific applications. We study the ways these eyes work, what arethe advantages of these peculiar eye arrangements, and whether these optics canbe used in advanced devices, e. g. space, and/or X—ray optics. We very brieflypresent and discuss the preliminary results.The mirror optics in these special eyes might be also applicable in technicaland scientific area, including astronomy and astrophysics. Already in past cen-tury, Angel Angel (1979) came up with an idea of technical application of theFish eye optics 95lobster mirror eye arrangement. He proposed to imitate principle of decapodeye imaging to construct a high-energy responsive telescope with wide field ofview. Eventually, this so-called lobster-eye X-ray telescope was assembled andit is nowadays used in astronomical satellites, such as VZLUSAT-1 (Pina et al.,2014, 2015; Urban et al., 2016; Baca et al., 2016).2. Refractive fish eyesRecent biomimetical applications of lobster eye in space telescopes raise upthe question about understanding of often strange animal eyes in general. Forexample, how the fish eye work and what are its optical parameters?In the 1st part of the study performed within the framework of the OpenScience IV and V projects of the Czech Academy of Sciences, we investigated an-imal mirror eyes, including fish mirror eyes (Hudec & Remisova, 2016; Remisova,2016). We have shown that in addition to widely discussed mirror eyes of de-capods (lobsters, crayfish, etc.) there are more recent discoveries of strange mir-ror eyes in very specific fishes which even resemble multi–layer, multi–mirroroptics in (possibly) active arrangement. This field is however very little investi-gated and understood, including possible technical and scientific applications.Figure 1. Refractive fish eye. The fish eye lenses tend to refract light resulting in asignificant amount of light at the retina. Spherical lens = good picture in the centre.http://animals.mom.me/structure-fishs-eye-10517.htm.In this contribution, we discuss fish (animal) optics in general, i.e. refractiveas well as reflective arrangements. These very preliminary results were obtainedin small student (high–school) project within Open Science V program.96 R.Hudec and S.MichalovaMany fish, even when unmoving have a greater monocular field of vision thanman, but much less binocular vision: While the FOV of human eye is typically154/150 deg horizontal and vertical with binocular FOV of 25 deg, for the fishlens (refractive eye) it is typically 165/134 deg and 12 deg 1.As the lens of fish eye is an almost spherical lens (and hence different opticalarrangement as used in our developed and manufactured fish–eye lenses, whichconsist of numerous pieces of glass), the fish vision is clearest in the middle ofthe picture, and to focus, they must point directly at something 2. Iris (Fig. 1)adjusts the light and it takes between 15 and 20 minutes to change light levels.Interesting feature is the fish UV view 3. Fish vision is mediated by fourvisual pigments. A mutation of the opsin on one of these pigments allows somevertebrates to absorb UV light. UV light can be detected for example by Rain-bow Trout and Goldfish. It may be related to foraging, communication or mateselection. Sometimes its used during only part of the life cycle. For example,brown trout uses UV vision only as a juvenile, to detect zooplankton, becauseof living in a shallow water. When they get older, they move to deeper waters.Literature research performed within the student project revealed that op-tical parameteres such as field of view (FOV), angular resolution (on–axis/off-axis), image distorsion, f/ratio, spectral sensitivity, etc., are only very rarelymentioned in the literature.3. Reflective fish eyesIn the past, all animal eyes were expected to work with light refraction, i.e.based on either single, or numerous, lenses. This picture changed when first ani-mal mirror eyes were described (in decapods) Land (1965, 1972, 1976). Then thepicture changed again more recently: in 2009, fish Dolichopteryx longipes wasdescribed by Wagner et al. (Wagner et al., 2014) as the first vertebrate possess-ing mirror eyes (Hudec & Remisova, 2016; Remisova, 2016). In 2014, Partridgeet al. (Partidge, 2014) described another fish, Rhynchohyalus natalensis, withreflective optics that belongs to the same family of fish Opisthoproctidae (alsoknown as barreleyes or spook fishes) as Dolichopteryx longipes. Although themirror eyes (diverticula) of these two species are similar, they vary in two im-portant attributes the origin of the reflective tissue and the orientation of theirreflective plates (Partidge, 2014).Figure 2 illustrates the transverse section of the entire right eye ofDolichopteryx longipes. It is showing both a main, upwardly directed tubularportion and a lateroventrally directed diverticulum. In the diverticulum, theretina lies on the lateral, caudal and rostral surfaces. The retina is thick andcomposed of layers of photoreceptor cells in the centre; however, it contains1http://en.wikipedia.org/wiki/Vision_in_fishes2http://www.earthlife.net/fish/sight.html3http://en.wikipedia.org/wiki/Brown_troutFish eye optics 97Figure 2. Transverse Section of the Entire Right Eye of Dolichopteryx longipes. It isshowing both a main, upwardly directed tubular portion and a lateroventrally directeddiverticulum. The section was taken 522 mm from the rostral edge of the eyea, argen-tea; ar, accessory retina; ce, ciliary epithelium; chg, choroid gland; dc, diverticularcornea; dr, diverticular retina; I, iris; m, mirror; mc, main cornea (partially removedfor facilitating the impregnation of tissue with resin); mr, main retina; oc, outer coatsof the eye, consisting of sclera, argentea, and choroid; rl, retractor lentis muscle (ven-tral part); s, septum between the main tubular eye and the diverticulum (figure andlegend adapted from (Wagner et al., 2014).thin single-cell layer in the edges. The retina of the diverticulum is continuouslyconnected with the retina of the tubular eye. The reflective layer (a biologicalmirror) lies on the medial surface of the diverticulum in the septum dividingthe eye parts. The mirror is approximately 0,2 mm thick and it is surprisinglyderived from the retina and not from the argentea. It consists of organized smallplates of high refractive index probably made of guanine. The plates are not ori-ented parallel to the surface of the septum, instead their angles gradually changeas their position from the geometric centre increases. This arrangement togetherwith the fact that the mirror is parabolic and off-axis provide the eye with awell-focused image high in brightness and contrast over most of the retina. How-ever, when the light beams are close to the vertical, only a part of the mirror isutilized so the image is less bright at the dorsal part of the retina (Wagner et al.,2014). To accommodate the eye for closer objects, the mirror would have to bemoved away from the retina. Since the retractor lentis a muscle of the tubularpart of the eye is attached to the septum, there might be a possibility of ac-commodation of the Dolichopteryx longipes diverticulum (Wagner et al., 2014;98 R.Hudec and S.MichalovaHudec & Remisova, 2016). Whereas the tubercular part of the eye probablyserves to capture dark objects against the residual sunlight, the diverticulumis supposed to detect primarily bioluminescent flashes coming from the deeperwater layers, i.e. from the ventral side of the fish (Wagner et al., 2014).4. Biomimetics of fish–eye opticsThe biomimetics of fish–eye optics is, in our oppinion, little understood. Albeitmost common fish eye is based on refraction and is represented by a sphere whichis moved along the eye optical axis, in specific fishes mentioned above were inaddition to refractive eyes also eyes based on mirrors found. The animal fish eye(based on refraction) arrangement is not quite identical with classical ”fish eye”lenses we know from optics and it is obvious that the optical performance andproperties are also different. In contrast to technical solution of fish–eye lenses(which usually consists of numerous lenses), the animal fish–eye arrangement isquite simple.Even much more complicated is the picture of specific mirror eyes found insome fishes described above and which are completely different from any opticalsystem we know from optics but may represent peculiar multi–layer, multi–mirror, and even active optics. The optical performance and arrangements ofthese eyes are far from to be investigated and understood, and this includespossible technical and scientific applications as well. We plan to focus on thisarea in the 2nd part of our high–school student project. The main goal is theunderstanding the way the strange fish mirror eyes work and finding out whetherthe mirror eye optics could be used in advanced optical devices, for example inastronomy.Since the light conditions in the space are in some cases similar to those inthe deep sea, the optical needs of deep sea organisms and astronomers mightbe similar. Therefore, some principles of the mirror eyes might be utilised asbiomimetic application in astronomical optical technology, as demonstrated incase of the lobster-eye X-ray telescopes (Angel, 1979; Schmidt, 1975; Hudecet al., 2015).5. ConclusionThe physical (optical) parameters were rarely measured in live organisms; mostof them come from the ray tracing of the eye models instead. However, there arevery few such results so far. Therefore, the information about the strange ani-mal, especially mirror eyes is very limited and in many cases even unavailable.For better understanding, more detailed anatomical examination is needed (e.g.of the ultrastructure of multilayer reflectors) as well as molecular and geneticanalyses together with advanced mathematical modelling of the ocular perfor-mance and investigating the image created in live specimens. In future, there isFish eye optics 99an enormous potential of further studies, especially of biomimetic application ofsome principles of the mirror eyes, such as the light and dark adaptation in thesuperposition eyes of crustaceans or the tilting of mirror plates in the recentlydescribed eyes of the spookfish (Dolichopteryx longipes).Acknowledgements. We acknowledge GA CR grant 13-33324S. We also acknowl-edge support by Academy of Science of the Czech Republic, within the Open ScienceIV and V programs. We thank Katerina Remisova for making available her literaturesearch for reflective animal (including fish) eyes.ReferencesAngel, J. R. P. 1979, Astrophys. J., 233, 364Baca, T., Platkevic, M., Jakubek, J., et al. 2016, Journal of Instrumentation, 11,C10007Hudec, R., Pina, L., Inneman, A., & Tichy, V. 2015, in Proceedings of the SPIE, Vol.9510, EUV and X-ray Optics: Synergy between Laboratory and Space IV, 95100AHudec, R. & Remisova, K. 2016, Application of Biomimetics Principles in Space Op-tics, ICSO2016 Proceedings available online at http://www.icsoproceedings.org/Land, M. 1965, The Journal of PhysiologyLand, M. 1972, Progress in Biophysics and Molecular BiologyLand, M. 1976, NaturePartidge, M. e. a. 2014, Proceedings. Biological sciences / The Royal Society,Pina, L., Burrows, D., Cash, W., et al. 2014, in Proceedings of the SPIE, Vol. 9207,Advances in X-Ray/EUV Optics and Components IX, 92070TPina, L., Hudec, R., Inneman, A., et al. 2015, in Proceedings of the SPIE, Vol. 9510,EUV and X-ray Optics: Synergy between Laboratory and Space IV, 951005P´ına, L., Hudec, R., Inneman, A. J., et al. 2016, in Proceedings of the SPIE, Vol. 9964,Advances in Laboratory-based X-Ray Sources, Optics, and Applications V, 99640BRemisova, K. 2016, Physiology of special mirror eyes of molluscs, crustaceans anddeep-sea fishSchmidt, W. K. H. 1975, Nuclear Instruments and Methods, 127, 285Urban, M., Nentvich, O., Stehlikova, V., et al. 2016, submitted to Acta AstronauticaWagner, H., Douglas, R., Frank, T., Roberts, N., & Partridge, J. 2014, Current Biology,108

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Fish eye optics

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