... Technologies that can help achieve that goal include microelectromechanical systems (MEMS), nanotechnology, acousto-optics, or high-speed tunable liquid crystal filters, but all ... For a uniformabsorber, the intensity of the... more
... Technologies that can help achieve that goal include microelectromechanical systems (MEMS), nanotechnology, acousto-optics, or high-speed tunable liquid crystal filters, but all ... For a uniformabsorber, the intensity of the trans-mitted signal decays exponentially with time as ...
Cyclohexane derivative stability is investigated using a combination of molecular modeling kits, conformational analysis, computational chemistry and polarimetry. Students build selected mono-and disubstituted cyclohexanes using model... more
Cyclohexane derivative stability is investigated using a combination of molecular modeling kits, conformational analysis, computational chemistry and polarimetry. Students build selected mono-and disubstituted cyclohexanes using model kits, predict the most stable conformation and calculate conformational equilibria. Students also construct cis-1,2-dimethylcyclohexane and trans-1,2-dimethylcyclohexane using the Avogadro computational chemistry program, optimize the structures and confirm the lowest energy conformations. Students utilize a polarimeter to measure the optical activity of several unknown cyclohexane derivatives and identify them from a list of possible (±) menthol and (±) carvone stereoisomers.
We show, both analytically and experimentally, that under common experimental conditions the interference pattern produced in a classic Young's double-slit experiment is indistinguishable from that generated by means of a doubly... more
We show, both analytically and experimentally, that under common experimental conditions the interference pattern produced in a classic Young's double-slit experiment is indistinguishable from that generated by means of a doubly refracting uniaxial crystal whose optic axis makes a skew angle with the light propagation direction. The equivalence between diffraction and crystal optics interference experiments, taken for granted by Arago and Fresnel in their pioneering research on the interference of polarized light beams, is thus rigorously proven.
Timely information on spatial variation of live fuel moisture is critical for fire risk assessment and behaviour modelling. Using an airborne synthetic aperture radar system, the sensitivity of radar data to live fuel (i.e. canopy... more
Timely information on spatial variation of live fuel moisture is critical for fire risk assessment and behaviour modelling. Using an airborne synthetic aperture radar system, the sensitivity of radar data to live fuel (i.e. canopy foliage) moisture was evaluated. Field and airborne measurements were collected over a 3-week period in a semiarid Australian forest dominated by white cypress pine (Callitris glaucophylla). Linear regression models were used to relate equivalent water thickness and live fuel moisture content to backscatter intensity and polarimetric decomposition components. Results showed that radar systems can provide estimates of live fuel moisture with similar or better accuracies for both equivalent water thickness (R2 = 0.7–0.8, root mean squared error (RMSE) = 15%) and live fuel moisture content (R2 = 0.6–0.7, RMSE = 10%) than those achieved in previous studies using optical-based vegetation indices. It was also possible to estimate soil moisture under the forest canopy with accuracies of 0.05 volume/volume (v v–1) (R2 = 0.5–0.6). This is particularly relevant in the context of fire management because moisture availability of fine fuels is related to soil water content.
This paper is presensing a computer software package for pre-processing of NASA/JPL's fully polarimetric AIRSAR imaging radar data. The software can be used to quickly calculate synthetic aperture radar images of any polarization state,... more
This paper is presensing a computer software package for pre-processing of NASA/JPL's fully polarimetric AIRSAR imaging radar data. The software can be used to quickly calculate synthetic aperture radar images of any polarization state, to show statistics for areas of interest, to compute polarization response diagrams (polarization signatures) and to optimize polarimetric discrimination for land-use classification, for example.
The purpose of this article is to present a new broadband Mueller ellipsometer designed to work in the mid-infrared range, from 3 to 14 μm. The Mueller ellipsometer, which can be mounted in reflection or in transmission configuration,... more
The purpose of this article is to present a new broadband Mueller ellipsometer designed to work in the mid-infrared range, from 3 to 14 μm. The Mueller ellipsometer, which can be mounted in reflection or in transmission configuration, consists of a polarization state generator (PSG), a sample holder, and a polarization state analyzer (PSA). The PSG consists of one linear polarizer and a retarder sequentially rotated to generate a set of four optimal polarization states. The retarder consists of a biprism made of two identical Fresnel rhombs disposed symmetrically and joined by an optical contact, giving the ensemble a “V” shape. Retardation is induced by the four total internal reflections that the beam undergoes when it propagates through the biprism. Total internal reflection allows the generation of a quasiachromatic retardation. The PSA is identical to the PSG, but with its optical elements mounted in reverse order. After a measurement run, the instrument yields a set of sixteen independent values, which is the minimum amount of data required to calculate the Mueller matrix of the sample. The design of the Mueller ellipsometer is based on the optimization of an objective criterion that allows for minimizing the propagation of errors from raw data to the Mueller matrix of the sample. The pseudo-achromatic optical elements ensure a homogeneous quality of the measurements for all wavelengths. The performance of the Mueller ellipsometer, in terms of precision and accuracy, is discussed and illustrated with a few examples.
We present mathematical formulas generalizing polarization gating (PG) techniques. PG refers to a collection of imaging methods based on the combination of different controlled polarization channels. In particular , we show how using the... more
We present mathematical formulas generalizing polarization gating (PG) techniques. PG refers to a collection of imaging methods based on the combination of different controlled polarization channels. In particular , we show how using the measured Mueller matrix (MM) of a sample, a widespread number of PG configurations can be evaluated just from analytical expressions based on the MM coefficients. We also show the interest of controlling the helicity of the states of polarization used for PG-based metrology, as this parameter has an impact in the image contrast of samples. In addition, we highlight the interest of combining PG techniques with tools of data analysis related to the MM formalism, such as the well-known MM decompositions. The method discussed in this work is illustrated with the results of polarimetric measurements done on artificial phantoms and real ex-vivo tissues.
We investigated the use of C-band RADARSAT Constellation Mission (RCM) synthetic aperture radar (SAR) for retrieval of ocean surface wind speeds by using four new channels (right circular transmit, vertical receive (RV); right circular... more
We investigated the use of C-band RADARSAT Constellation Mission (RCM) synthetic aperture radar (SAR) for retrieval of ocean surface wind speeds by using four new channels (right circular transmit, vertical receive (RV); right circular transmit, horizontal receive (RH); right circular transmit, left circular transmit (RL); and right circular transmit, right circular receive (RR)) in compact polarimetry (CP) mode. Using 256 buoy measurements collocated with RADARSAT-2 fine beam quad-polarized scenes, RCM CP data was simulated using a “CP simulator”. Provided that the relative wind direction is known, our results demonstrate that wind speed can be retrieved from RV, RH and RL polarization channels using existing C-band model (CMOD) geophysical model function (GMF) and polarization ratio (PR) models. Simulated RR-polarized radar returns have a strong linear relationship with speed and are less sensitive to relative wind direction and incidence angle. Therefore, a model is proposed for ...
A novel experiment was prepared to help chemistry educators to improve the stereochemistry curriculum of secondary school students and undergraduate students. Based on polarimetry and Vitamin C, chemistry educators are now provided with... more
A novel experiment was prepared to help chemistry educators to improve the stereochemistry curriculum of secondary school students and undergraduate students. Based on polarimetry and Vitamin C, chemistry educators are now provided with an experiment that takes into account the delocalization of electrons, and the interactions with plane-polarized light in atomic bonds.
An all-fiber optic catheter-based polarization-sensitive optical coherence tomography system is demonstrated. A novel multiplexing method was used to illuminate the sample, splitting the light from a 58.5 kHz Fourier-domain mode-locked... more
An all-fiber optic catheter-based polarization-sensitive optical coherence tomography system is demonstrated. A novel multiplexing method was used to illuminate the sample, splitting the light from a 58.5 kHz Fourier-domain mode-locked laser such that two different polarization states, alternated in time, are generated by two semiconductor optical amplifiers. A 2.3 mm forward-view cone-scanning catheter probe was designed, fabricated, and used to acquire sample scattering intensity and phase retardation images. The system was first verified with a quarter-wave plate and then by obtaining intensity and phase retardation images of high-birefringence plastic, human skin in vivo, and untreated and thermally ablated porcine myocardium ex vivo. The system can potentially in vivo image of the cardiac wall to aid radio-frequency ablation therapy for cardiac arrhythmias.
In this Letter we describe an experiment in which coherent light is sent through a calcite crystal that separates the photons by their polarization. The two beams are then let to superpose, and this recombined beam is used to measure the... more
In this Letter we describe an experiment in which coherent light is sent through a calcite crystal that separates the photons by their polarization. The two beams are then let to superpose, and this recombined beam is used to measure the Mueller matrix of the system. Results are interpreted according to our recent formalism of coherent superposition in material media. This is the first experimental implementation of a Young's experiment with complete polarimetry, and it is demonstrated that our method can be used for the experimental synthesis of optical devices with on-demand optical properties.
We present the design and calibration of a spectroscopic sensitive polarimeter. The polarimeter can measure the full Stokes vector in the wavelength range 550 to 750 nm with 1-nm resolution and consists of a fiber-based spectrophotometer,... more
We present the design and calibration of a spectroscopic sensitive polarimeter. The polarimeter can measure the full Stokes vector in the wavelength range 550 to 750 nm with 1-nm resolution and consists of a fiber-based spectrophotometer, a white light emitting diode light source, two liquid crystal retarders, and one polarizer. Calibration of the system is achieved with a scheme that does not require knowledge of the polarizing elements' orientation or retardation. Six intensity spectra are required to calculate the full spectrum Stokes vector. Error in the polarimeter is less than 5%. We report the Stokes vectors for light transmitted through nonscattering polarizing elements as well as a measurement of the depolarizing properties of chicken muscle at several wavelengths.
We present mathematical formulas generalizing polarization gating (PG) techniques. PG refers to a collection of imaging methods based on the combination of different controlled polarization channels. In particular, we show how using the... more
We present mathematical formulas generalizing polarization gating (PG) techniques. PG refers to a collection of imaging methods based on the combination of different controlled polarization channels. In particular, we show how using the measured Mueller matrix (MM) of a sample, a widespread number of PG configurations can be evaluated just from analytical expressions based on the MM coefficients. We also show the interest of controlling the helicity of the states of polarization used for PG-based metrology, as this parameter has an impact in the image contrast of samples. In addition, we highlight the interest of combining PG techniques with tools of data analysis related to the MM formalism, such as the well-known MM decompositions. The method discussed in this work is illustrated with the results of polarimetric measurements done on artificial phantoms and real ex-vivo tissues.
Satellite Low Noise Block-down convertors (LNBs) have been evaluated for use in amplitude and intensity interferometry. LNBs have been found to have a high performance to cost ratio which is beneficial for any sensor system. They are... more
Satellite Low Noise Block-down convertors (LNBs) have been evaluated for use in amplitude and intensity interferometry. LNBs have been found to have a high performance to cost ratio which is beneficial for any sensor system. They are investigated here for a diversity of applications from the derisking of subsystems for next generation aperture synthesis imagers having hundreds of channels [1] to a platform for the investigation of phase recovery in intensity interferometry and experimentation in entangled photons. Measured noise temperatures of LNBs were found to lie between 170 K and 300 K which is higher than typical manufacturers' specifications. A twin channel interferometer system was developed using satellite receiver feeds and LNBs at the front-end, other amplifiers, mixers, filters and local oscillators at intermediate stages, and 8-bit USB ADCs sampling synchronously at 100 MHz and a PC for data processing. LabVIEW was used to digitally demodulate the sampled data and p...
