Polarized light, circular light, and also scarabs have sometimes been mentioned and debated in Alchemy. Dennis H. Goldstein, Optics and Photonics researcher, investigated further A. A. Michelson’s observation in 1911 that scarabs could send back annular polarized light from a falling unpolarized beam.
There might be something interesting in their articles and Pete Vukusic and Mohan Srinivasarao.
“Beetles of the scarab family have been found to reflect circularly polarized light from incident unpolarized light. Many known animals use polarized light in some form and several that create it, but there are few examples of the creation of circularly polarized light in nature”. This is the abstract from Dennis H. Goldstein’s conference paper presented at the 50th annual meeting of SPIE, Optics and Photonics, San Diego, California, 1-4 August 2005.
Alchemists haven’t the slightest idea about what is happening inside their vessels. They are only aware of Secret Fire and hardly know how to extract it. Scarce knowledge has always been an alchemist’s companion. I chose to name “Alchemy & Nature” this new category on the naturally occurring events that might be involved in our research, and I did not dare to take “Alchemy and Science”.
Dennis H. Goldstein: REFLECTION PROPERTIES OF SCARABAEIDAE
INTRODUCTION
“The creation of polarized light is common in nature, but generating circularly polarized light from unpolarized light is rare. A. A. Michelson noted in 1911 that reflected light from the scarab beetle Plusiotis resplendens, a beetle that appears 2-9 to have been fashioned out of brass or gold, is circularly polarized. Later authors have also discussed this effect, and it has been found that only scarabs can generate circularly polarized light. Fig. 1a shows Plusiotis resplendens in the absence of polarizing optics, and Fig. 1b shows the animal with a circular polarizer in front of the camera. The effect for this creature is more subtle than other scarabs; it is difficult to discern the difference between these two images. A more impressive example is Plusiotis gloriosa, shown in Fig. 2. I have examined several of these scarabs for this study and have measured the spectral reflectance and Mueller matrix for the visible region to quantify this effect. “
CONCLUSIONS
“I have presented reflectance spectra and Mueller matrices for two scarab beetles. This is the first explicit instance of this data in the literature. Michelson (1911) describes that the hand of the circular polarization reverses from the blue 25 ends of the spectrum to the red, and Gaubert (1924)agrees with this. In a much later paper (1969), Neville and Caveney disagree. The current results validate the results of Michelson and Gaubert concerning this hand reversal, and in fact, there are two reversals in the visible wavelength region”.
All Polarimetric and Reflectometric Parameters with Diagrams and References had been available, together with the whole document, at http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA437788, but the link seems to be expired now;
Pete Vukusic later improved the subject published by AAAS in SCIENCE, VOL 325, 24 JULY 2009.
Pete Vukusic: EVOLUTIONARY PHOTONICS WITH A TWIST.
“Complex helical nanostructures can cause the iridescent appearance of the hard forewings of scarab beetles.
Left-handed circularly polarized reflection means that from the observer’s perspective, the electric field vector of the light reflected from the scarab beetle describes a left-handed corkscrew, or helix, along its direction of propagation. Circularly polarized reflection from specific beetles was first observed nearly a century ago. Plusiotis gloriosa’s tendency to do this is thus not an isolated example, but the attribute is rare. It requires a distinct azimuthally twisted, or helical, character in the nanostructure that forms the first few micrometers of its elytra. In these scarab beetles, the spatial pitch of this helix creates the intrinsic periodicity that, to human vision, produces bright iridescent color. An example of this is shown in Plusiotis alphabarrerai . What appears to human eyes as green iridescence from certain scarab beetles, such as shown here, mostly constitutes circularly polarized color…
… Synthetic systems that exhibit strongly circularly polarized color reflections include certain layered mesophases, specifically those associated with cholesteric liquid crystals (also known as chiral nematic liquid crystals).
Their circularly polarized optical properties arise because their constituent molecules lack inversion symmetry. This produces intermolecular forces that favor a specific slight azimuthal twist through the whole system…
… However, in Plusiotis gloriosa (image 2) and several other Rutelinae, the structural complexity goes beyond mere helically ordered layering. These beetles’ elytral surfaces consist of mostly hexagonal micrometer-scale multicolored cells…
… The helical beetle ultrastructure is arguably too complex and too costly to produce without the benefit of a suitable optical selection advantage, such as effective signaling. For example, the strong circularly polarized reflection observed in the beetles may play a role in intraspecific communication. This is especially true for another scarab, Plusiotis resplendens (image 1). It exhibits broad, solid band reflection of both left and right-handed circularly polarized light due to the presence of two chirped helical layered regions separated by a half-wave plate…
….Despite some initial behavioral studies, whether the circularly polarized reflection from these special beetles provides a communication channel remains unknown. However, Chiou et al. recently showed that such communication is possible for a marine crustacean: the stomatopod Odontodactylus sp. Not only do these species signal brightly using circularly polarized colored light reflected from two posterior abdominal appendages, but it also responds behaviorally to circularly polarized stimuli. Its method for doing so is elegant. Chiou et al. revealed that incident circularly polarized light is converted to linearly polarized light when transmitted through a quarter wave plate in specific cells of the eyes’ mid-band region.”
In 2009 research by Mohan Srinivasarao focused on the material source of the circularly polarized light in the scarab shell.
TITLE: A structure much like a liquid crystal allows the shell of a scarab beetle to circularly polarize light.
Mohan Srinivasarao of the Georgia Institute of Technology and colleagues have used microscopy techniques to show that the iridescent green scarab beetle (Plusiotis gloriosa) has a helical shell structure, rather like a “cholesteric” liquid crystal.
“This study is critical because it highlights how animals produce very complex nanostructures by self-assembly, the resulting structures are optically active and produce brilliant metallic green structures, and the optical activity results in reflected light being circularly polarized.
There are many examples of insect shells, fish scales, bird feathers, and other animal kingdom objects with unusual optical properties. Sometimes researchers find the properties surpass those in manmade materials so they can copy the animal’s design. In 2007, researchers discovered that a tropical beetle’s oddly bright white shell resulted from an “aperiodic” shell structure, and said it could lead to a new type of super-white, synthetic material.
Using reflected-light microscopy, Srinivasarao’s group could see how the shell of Plusiotis gloriosa changes color at different angles, producing the iridescent colors visible to the human eye. However, the group could discern a helical structure using laser-scanning confocal microscopy for higher magnifications. This structure resembled a cholesteric liquid crystal, which circularly polarizes light due to defects that twist its ordered layers of molecules to one another.
Srinivasarao thinks the scarab beetle’s shell could, like other animals, be mimicked for manmade applications. One could envision making very shiny metallic colors by taking a cholesteric fluid and varying the conditions at which the surface defects appear”.
The article is taken from physicsworld. com.