Miniaturization of optical components, specifically the reduction in thickness created by using planar optical devices, makes light manipulation by diffraction more and more attractive. Optical gratings based on volume Holographic Optical Elements (vHOEs) have the advantage over surface gratings as they reconstruct only a single diffraction order and hence provide high diffraction efficiencies, selectivity and remain fully transparent in the off-Bragg condition.
Guiding light inside an optically transparent medium by total internal reflection (TIR) is common and useful in thin planar optical devices. vHOEs offer unique ways to create selective in- and out-coupling of TIR light. As such vHOEs typically have to be recorded in an edge-lit configuration as the necessary high diffraction angles could not be generated by two free-space beams outside the medium. To record such an edge-lit vHOE, bulky recording blocks or liquid baths are used in complex and hard to align recording setups.
We present in this paper our findings to use instant-developing photopolymer film (Bayfol® HX) to generate 2nd harmonics in the index profile of phase gratings while using free-space recording setups. Those 2nd harmonic components enable the vHOE to diffract at such large angles that they replay in an edge-lit configuration. We will discuss in this paper selected materials and beneficial recording parameters to tune the diffraction efficiency towards 2nd harmonic replay. By this - in reported specific cases - the cumbersome and complex edge-lit recording can be substituted by easy-to-use free-space setups. This process significantly simplifies master recordings for vHOEs with edge-lit functionalities which later can be used in contact copy schemes for mass replication.
Manipulating light with optical gratings based on volume Holographic Optical Elements (vHOEs), also known as volume Bragg gratings, has the advantage to reconstruct only the first diffraction order and hence provide high diffraction efficiencies and angular selectivity. In addition, they offer the further benefit to be fully transparent in the off- Bragg condition like it is required in optical combiners. We present the latest status of our instant-developing photopolymer film technology (Bayfol® HX) and show beneficial recording parameters - specifically we discuss the challenges to record transmission vHOEs and how to overcome them. Experimental results on color transmission recordings are shown and it is demonstrated that those match perfectly to Kogelniks coupled wave theory. It is recommended to adopt the dynamic range of the recording media by proper choice of recording dosage, recording power, beam ratio and photopolymer film type to the desired transmission vHOE design.
We have been developing a new class of recording materials for volume holography, offering the advantages of full
color recording and depth tuning without any chemical or thermal processing, combined with low shrinkage and
detuning. These photopolymers are based on the two-chemistry concept in which the writing chemistry is dissolved in a
preformed polymeric network. This network gives the necessary mechanical stability to the material prior to recording.
In this paper we describe several aspects of holographic recording into Bayfol® HX which are beneficial for its effective
use and discuss them within a more elaborate reaction-diffusion model. Inhibition phenomena and the influence of precure
are studied within this model and are investigated experimentally for single hologram recording and angular
multiplexed hologram recordings. Also the dark reaction after the exposure period and the minimum allowable waiting
time for full hologram formation are addressed. The proper understanding of these phenomena is important for the
optimal usage of these new materials, in for example step-and-repeat mass production of holograms.
We have been developing a new class of recording materials for volume holography, offering the advantages for full
color recording and depth tuning without any chemical or thermal processing, combined with low shrinkage and
detuning. These photopolymers are based on the two chemistry concept in which the writing chemistry is dissolved in a
preformed polymeric network. This network gives the necessary mechanical stability to the material prior to recording.
In this paper we show that the recording process in these materials can be successfully described within a reactiondiffusion
model. For the first time the combination of plane-wave recording data in transmission and reflection geometry
was used to extract the model parameters. This was achieved via a master curve construction of the respective power
density response functions of the photopolymer at saturation recording conditions. Within that model, power density
response, spatial frequency response, non-locality effects, beam ratio effects and even dosage response can be predicted
and explained for a wide range of CW recording conditions which are important for various holographic applications of
these new materials.
This paper describes a new class of recording materials for volume holographic applications suitable to meet commercial
manufacturing needs. These next-generation holographic photopolymers have the ability to satisfy the unmet demand
for color and depth tuning that is only possible with volume holograms. Unlike earlier holographic photopolymers, these
new materials offer the advantages of no chemical or thermal processing combined with low shrinkage and detuning.
Furthermore, these materials exhibit high transparency, a high resolution of more than 5000 lines/mm and are
environmentally robust. Bayer MaterialScience plans to commercialize these materials, which combine excellent
holographic characteristics with compatibility to mass-production processes. In this paper, we will briefly discuss the
potential markets and applications for a new photopolymer, describe the attributes of this new class of photopolymers,
relate their ease of use in holographic recording, and discuss potential applications of such materials..
A strategy for increasing the wavelength selectivity and responsivity of hybrid dye/superconductor optical sensors is described. Here, reflective 'mirror layers' deposited on the top surface of YBa2Cu3O7-(delta ) thin film devices are used to enhance the optical performance characteristics of such hybrid sensors. Quantification of the wavelength-selectivity for such detector structures is detailed for both dye/high-Tc superconductor and dye/mirror-layer/high-Tc superconductor systems. Optical response studies of the structures suggest that the inclusion of the mirror layer serves to enhance the wavelength-selectivity of the detector. Consequently, only the on-resonance signals captured by the dye layer are effectively sensed by the superconductor element. Measurements of the spectral response properties of the mirror layer-modified hybrid detectors show that energy transfer between the dye and superconducting elements is not diminished by the presence of this reflective layer.
High temperature superconductors provide enhanced sensitivity capabilities as chemical/biological agent detectors. State-of-the-art advances in ruggedizing superconducting platforms make them much more robust for field applications. In addition, microminiaturization and advances in refrigeration have enabled the systems engineering of portable, durable, survivable, low power requirement devices. This presentation describes a prototype system employing YBCO (yttrium barium copper oxide) superconducting quantum interference devices (SQUIDS) with specific biolayer detection dye coatings. These devices may be deployed as specific stand-off detectors, or potentially reconfigured as point sensors. A library of pattern recognition algorithms provides the reference template for the system. The human-system interface will provide a 'yes/no' agent confirmation for the environment being queried, and associated confidence value. This prototype detection system has great potential for deployment in support of hostage rescue/rapid response teams, DMAT, and urban search and rescue. The preparation and characterization of a new generation of optical sensors fabricated from high-temperature superconductor (HTSC) thin films is reported herein. These new hybrid devices are fashioned using HTSC thin films which are coated with organic dye overlayers. These systems are shown to respond selectively to those wavelengths which are absorbed strongly by the molecular dye. Methods for fabricating the superconductor element and depositing the dye layer are discussed. Moreover, resistivity versus temperature measurements before and after dye deposition are utilized to characterize these hybrid structures. The unique optical response properties of these hybrid sensors are also detailed.
The preparation and characterization of a new generation of optical sensors fabricated from high-temperature superconductor (HTSC) thin films is reported herein. These new hybrid devices are fashioned using HTSC thin films which are coated with organic dye overlayers. These systems are shown to respond selectively to those wavelengths which are absorbed strongly by the molecular dye. Methods for fabricating the superconductor element and depositing the dye layer are discussed. Moreover, resistivity versus temperature measurements before and after dye deposition are utilized to characterize these hybrid structures. The unique optical response properties of these hybrid sensors are also detailed.
The preparation and characterization of a new generation of hybrid optical sensors fabricated from high-temperature superconductor thin films coated with organic dye overlayers is described herein. These dye-coated superconductor structures respond selectively to those wavelengths of light which are absorbed strongly by the molecular dye. Methods for preparing such optical sensors are details. Scanning electron microscopy, resistivity vs. temperature and optical measurements are exploited to characterize the hybrid devices.
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