Modulatable reflector
A radiation reflecting element ( 34 ), more particularly a so-called triple prism or a retro-reflector, is provided with a photonic element on a surface serving either for the passage of an electromagnetic energy beam (light) ( 40,43 ) or on one of the surfaces ( 30–32 ) serving for the deflection of the beam. The photonic element is characterized by the presence of a photonic band gap ( 5,7 ) capable of being shifted e.g. by an electric signal. Thus, with an appropriate selection of the wavelength of the light beam, the photonic element can be switched from reflective to transmissive, thereby allowing a modulation of the light beam with a high modulation depth.
1. An element reflecting electromagnetic radiation, specifically light, wherein said element comprises a photonic element having a controllable band gap, the photonic element being disposed in the beam path of and/or on a surface reflecting said radiation, for modulating the radiation passing through said element, wherein said element is essentially a prism and in particular a triple prism, and said photonic element is provided on at least one, preferably all prism surfaces intended for reflecting said radiation.
2. The radiation reflecting element of claim 1 , wherein said photonic element is controllable by means of electric signals.
3. The radiation reflecting element of claim 2 , wherein said photonic element is essentially composed of a photonic material in a liquid crystal environment, such that a photonic band gap of said photonic material is capable of being influenced by influencing the liquid crystal material in the nematic and/or ferroelectric state by an electric field.
4. An element reflecting electromagnetic radiation, specifically light, wherein said element comprises a photonic element having a controllable band gap, the photonic element being disposed in the beam path of and/or on a surface reflecting said radiation, for modulating the radiation passing through said element, wherein said reflecting element is a prism, preferably a triple prism, and said photonic element is disposed on the surface serving for the entrance and the exit of a beam of the radiation.
5. An object identification system comprising a laser of a determined wavelength for producing an electromagnetic beam, specifically a light beam, and at least one element reflecting electromagnetic radiation, specifically light, wherein each of said at least one element comprises a photonic element having a controllable band gap, the photonic element being disposed in the beam path of and/or on a surface reflecting said radiation, for modulating the radiation passing through said element, said at least one element being provided on an object, wherein at least one, preferably all photonic elements of said at least one radiation reflecting element are chosen such that the reflective properties of the at least one radiation reflecting element are adjustable by controlling the photonic element or elements, more particularly switchable from high reflectivity to low reflectivity, for modulating the reflected light beam with data.
6. A method of modulating a beam of electromagnetic radiation, more specifically of a light beam, using an element reflecting electromagnetic radiation, specifically light, wherein said element comprises a photonic element having a controllable band gap, the photonic element being disposed in the beam path of and/or on a surface reflecting said radiation, for modulating the radiation passing through said element, said element transmitting data, said beam comprising a component of a wavelength for which said radiation reflecting element is switchable, by influencing at least a portion of the photonic element thereof, between two states of higher and lower transparency and/or reflectivity.
7. The method of claim 6 , wherein said beam is essentially composed of radiation of the wavelength that can be influenced.
8. The radiation reflecting element of claim 4 , wherein said photonic element is controllable by means of a electric signals.
9. The radiation reflecting element of claim 8 , wherein said photonic element is essentially composed of a photonic material in a liquid crystal environment, such that a photonic band gap of said photonic material is capable of being influenced by influencing the liquid crystal material in the nematic and/or ferroelectric state by an electric field.