Applied Optics (APPL OPTICS)

Publications in this journal

• Article: Experimental investigation of the quality of ghost imaging via sparsity constraints

  Wenlin Gong, Zunwang Bo, Enrong Li, Shensheng Han
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  ABSTRACT: Sampling number and detection signal-to-noise ratio (SNR) are two major factors influencing imaging quality. Combining the image’s sparsity in the representation basis with the ghost imaging (GI) approach, GI via sparsity constraints (GISC) can nonlocally image the object even when the measurement number is far fewer than the Nyquist criteria required for the conventional GI reconstruction algorithm. The influence of receiving the system’s numerical aperture and detection SNR in the test path to GISC is studied through experiments. It is also shown that the quality of GISC depends on the object’s sparse representation basis.
  Applied Optics 05/2013; 52(15):3510.
• Article: Simultaneous physical retrieval of surface emissivity spectrum and atmospheric parameters from infrared atmospheric sounder interferometer spectral radiances

  Guido Masiello, Carmine Serio
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  ABSTRACT: The problem of simultaneous physical retrieval of surface emissivity, skin temperature, and temperature, water–vapor, and ozone atmospheric profiles from high-spectral-resolution observations in the infrared is formulated according to an inverse problem with multiple regularization parameters. A methodology has been set up, which seeks an effective solution to the inverse problem in a generalized L-curve criterion framework. The a priori information for the surface emissivity is obtained on the basis of laboratory data alone, and that for the atmospheric parameters by climatology or weather forecasts. To ensure that we deal with a problem of fewer unknowns than observations, the dimensionality of the emissivity is reduced through expansion in Fourier series. The main objective of this study is to demonstrate the simultaneous retrieval of emissivity, skin temperature, and atmospheric parameters with a two-dimensional L-curve criterion. The procedure has been demonstrated with spectra observed from the infrared atmospheric sounder interferometer, flying onboard the European Meteorological Operational satellite. To check the quality and reliability of the methodology, we have used spectra recorded over regions characterized by known or stable emissivity. These include sea surface, for which effective emissivity models are known, and arid lands (Sahara and Namib Deserts) that are known to exhibit the characteristic spectral signature of quartz-rich sand.
  Applied Optics 04/2013; 52(11):2428-2446.
• Article: Feasibility of utilizing Cherenkov Telescope Array gamma-ray telescopes as free-space optical communication ground stations

  Alberto Carrasco-Casado, Mariafernanda Vilera, Ricardo Vergaz, Juan Francisco Cabrero
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  ABSTRACT: The signals that will be received on Earth from deep-space probes in future implementations of free-space optical communication will be extremely weak, and new ground stations will have to be developed in order to support these links. This paper addresses the feasibility of using the technology developed in the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) observatory in the implementation of a new kind of ground station. Among the main advantages that these telescopes provide are the much larger apertures needed to overcome the power limitation that ground-based gamma-ray astronomy and optical communication both have. Also, the large number of big telescopes that will be built for CTA will make it possible to reduce costs by economy-scale production, enabling optical communications in the large telescopes that will be needed for future deep-space links.
  Applied Optics 04/2013; 52(11):2353-2362.
• Article: Absolute self-calibrated room-temperature terahertz powermeter

  Christophe Pradere, Jean-Pascal Caumes, Jean Toutain, Emmanuel Abraham, Bruno Chassagne, Jean-Christophe Batsale
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  ABSTRACT: Coupling optical and thermal properties of a terahertz (THz) thermal converter based on the Seebeck effect provides an unsupplied room-temperature measuring device dedicated to THz power metrology. Performance characteristics such as broadband response (0–30 THz), high sensitivity (<25 μW ·Hz−0.5), and the possibility to develop an internal absolute self-calibration estimated at 9.93 W · V−1 are reported. Advantages and drawbacks of this THz powermeter are discussed.
  Applied Optics 04/2013;
• Article: Suresh Ponnan, Mariyal Chelladurai, Rajesh K. Balasundaram, Pillai T. V. Sivasubramonia, and Z. Jaroszewicz: " Generation of a strong uniform transversely polarized nondiffracting beam using a high-numerical-aperture lens axicon with a binary phase mask", Appl. Opt. 53, No. 2, (2013), 849-853.

  Suresh Ponnan, Mariyal Chelladurai, Rajesh K. Balasundaram, Pillai T. V. Sivasubramonia, and Z. Jaroszewicz
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  ABSTRACT: We present a theoretical approach to generate a nondiffracting beam with extended depth of focus (DOF) and a smaller focal spot along the optical axis, by tight focusing of an azimuthally polarized beam with a circular symmetrical binary phase mask and an interference effect over a high-numerical-aperture (NA) lens axicon system. We find a general azimuthal diffraction integral for the circularly symmetric binary phase mask and examine it in two special cases: a high-NA lens and a high-NA lens axicon. The azimuthally polarized beam remains well behaved in both cases. We verify that the longitudinal component generated by azimuthally polarized illumination produces the narrowest spot size for a wide range of geometries. Finally, we discuss the effects of tight focusing on a dielectric interface and provide some ideas for circumventing the effects of the binary phase mask interface and even utilize them for spot size reduction.
  Applied Optics 01/2013; 53(2):849-853.
• Article: Color image security system using double random-structured phase encoding in gyrator transform domain

  Muhammad Rafiq Abuturab
  Applied Optics 05/2012;
• Article: Analysis on the saturation of refractive index modulation in fiber Bragg gratings (FBGs) written by partially coherent UV beams

  Ramakanta Mahakud, Om Prakash, Shankar V. Nakhe, Sudhir Kumar Dixit
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  ABSTRACT: We present an analysis on the saturation of refractive index modulation of fiber Bragg gratings written in nonhydrogenated Ge-B co-doped single-mode photosensitive optical fiber by partially coherent pulsed UV beams. The UV beams of different spatial coherence properties were generated by second harmonic conversion of high repetition rate, high average power copper vapor laser (CVL) oscillators with different optical resonators. It is observed that for UV beams of higher spatial coherence, the fiber Bragg grating reflectivity growth was faster and saturation of refractive index modulation was higher. The experimental results are explained with the help of a physical model based on exponential decay of defect centers per unit volume on UV absorption in the fiber core. The subsequent increase in the refractive index was attributed to the structural modification and densification of the fiber core.
  Applied Optics 04/2012; Vol. 51, No. 12(159045):1828-1835.
• Article: Spectral calibration of radiometric detectors using tunable laser sources

  schuster, nevas, sperling, völker
  Applied Optics 04/2012; 51(12):1950-1961.
• Article: Comparative Study of Nd:YAG Laser-Induced Breakdown Spectroscopy (LIBS) and Transversely Excited Atmospheric CO2 Laser-Induced Gas Plasma Spectroscopy on CCA Preservative-Treated Wood

  Ali Khumaeni, Zener Sukra Lie, Hideaki Niki, Yong Inn Lee, Kazuyoshi Kurihara, Motoomi Wakasugi, Touru Takahashi, Kiichiro Kagawa
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  ABSTRACT: Taking advantage of the specific characteristics of a transversely excited atmospheric (TEA) CO2 laser, a sophisticated technique for the analysis of chromated copper arsenate (CCA) in wood samples has been developed. In this study, a CCA-treated wood sample with a dimension of 20  mm×20  mm and a thickness of 2 mm was attached in contact to a nickel plate (20  mm×20  mm×0.15  mm), which functions as a subtarget. When the TEA CO2 laser was successively irradiated onto the wood surface, a hole with a diameter of approximately 2.5 mm was produced inside the sample and the laser beam was directly impinged onto the metal subtarget. Strong and stable gas plasma with a very large diameter of approximately 10 mm was induced once the laser beam had directly struck the metal subtarget. This gas plasma then interacted with the fine particles of the sample inside the hole and finally the particles were effectively dissociated and excited in the gas plasma region. By using this technique, high precision and sensitive analysis of CCA-treated wood sample was realized. A linear calibration curve of Cr was successfully made using the CCA-treated wood sample. The detection limits of Cr, Cu, and As were estimated to be approximately 1, 2, and 15  mg/kg, respectively. In the case of standard LIBS using the Nd:YAG laser, the analytical intensities fluctuate and the detection limit was much lower at approximately one-tenth that of TEA CO2 laser.
  Applied Optics 03/2012; 51(7-B121-B129):B121-B129.
• Article: Quantitative phase microscopy using dual plane in-line digital holography

  ◦Bhargab Das, Chandra S. Yelleswarapu, D. V. G. L. N. Rao
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  ABSTRACT: We present detailed theoretical evaluation and thorough experimental investigation of quantitative phase imaging using our previously demonstrated dual-plane in-line digital holographic microscopy technique [Opt. Lett.35, 3426 (2010)10.1364/OL.35.003426OPLEDP0146-9592]. This evaluation is based on the recording of two interferograms at slightly different planes and numerically reconstructing the object information. The zero-order diffracted wave is eliminated by using the method of subtraction of average intensity of the entire hologram, and the twin-image diffracted wave is removed by Fourier domain processing of the two recorded holograms. Experiments are performed using controlled amplitude and phase objects and human muscle cells to demonstrate the potential of this technique.
  Applied Optics 03/2012; 51(9):1387.