Source Of Scattered Light Research Articles

High-brightness photo-injector with standing-wave buncher-based ballistic bunching scheme for inverse Compton scattering light source

High-brightness photo-injector with standing-wave buncher-based ballistic bunching scheme for inverse Compton scattering light source

Functional photoacoustic remote sensing microscopy using a stabilized temperature-regulated stimulated Raman scattering light source.

Stimulated Raman scattering (SRS) has been widely used in functional photoacoustic microscopy to generate multiwavelength light and target multiple chromophores inside tissues. Despite offering a simple, cost-effective technique with a high pulse repetition rate; it suffers from pulse-to-pulse intensity fluctuations and power drift that can affect image quality. Here, we propose a new technique to improve the temporal stability of the pulsed SRS multiwavelength source. We achieve this by lowering the temperature of the SRS medium. The results suggest that a decrease in temperature causes an improvement of temporal stability of the output, considerable rise in the intensity of the SRS peaks, and significant increase of SRS cross section. The application of the method is shown for in vivo functional imaging of capillary networks in a chicken embryo chorioallantois membrane using photoacoustic remote sensing microscopy.

Polarization transfer from a laser to x rays via Thomson scattering with relativistic electrons: A dipole radiation perspective

A Thomson scattering light source can produce polarization-controllable x rays with quasi-monochromaticity and high brightness, making it an excellent probe for x-ray imaging and nuclear physics research. In this paper, a clear physical picture of the polarization transfer process from a laser to x rays is given based on a dipole radiation model. For arbitrary interaction geometries between a laser and relativistic electrons, the electric field relation between the scattered x rays and the laser is derived analytically. The result shows that the polarization characteristics of the laser can be completely transferred into x rays, regardless of the interaction geometry. Meanwhile, the polarization of scattered x rays is dependent on the collecting angle. As the collecting angle increases, both the degree of polarization (DOP) and the bandwidth of scattered x rays will be degraded. A collecting angle confining scattered x rays of 5% rms bandwidth can guarantee a DOP higher than 97% for both linear and circular polarizations. A method for any polarization control of scattered x rays is demonstrated by using wave plates for the laser. Both the rotation of linear polarization and the switch of polarization state from linear polarization to circular polarization and from left-handed polarization to right-handed polarization can be easily realized.

Linearly polarized X-ray fluorescence computed tomography based on a Thomson scattering light source: a Monte Carlo study.

A Thomson scattering X-ray source can provide quasi-monochromatic, continuously energy-tunable, polarization-controllable and high-brightness X-rays, which makes it an excellent tool for X-ray fluorescence computed tomography (XFCT). In this paper, we examined the suppression of Compton scattering background in XFCT using the linearly polarized X-rays and the implementation feasibility of linearly polarized XFCT based on this type of light source, concerning the influence of phantom attenuation and the sampling strategy, its advantage over K-edge subtraction computed tomography (CT), the imaging time, and the potential pulse pile-up effect by Monte Carlo simulations. A fan beam and pinhole collimator geometry were adopted in the simulation and the phantom was a polymethyl methacrylate cylinder inside which were gadolinium (Gd)-loaded water solutions with Gd concentrations ranging from 0.2 to 4.0 wt%. Compared with the case of vertical polarization, Compton scattering was suppressed by about 1.6 times using horizontal polarization. An accurate image of the Gd-containing phantom was successfully reconstructed with both spatial and quantitative identification, and good linearity between the reconstructed value and the Gd concentration was verified. When the attenuation effect cannot be neglected, one full cycle (360°) sampling and the attenuation correction became necessary. Compared with the results of K-edge subtraction CT, the contrast-to-noise ratio values of XFCT were improved by 2.03 and 1.04 times at low Gd concentrations of 0.2 and 0.5 wt%, respectively. When the flux of a Thomson scattering light source reaches 1013 photons s-1, it is possible to finish the data acquisition of XFCT at the minute or second level without introducing pulse pile-up effects.

Fiber Optical Parametric Oscillator and Amplifier for CARS Spectroscopy

We demonstrated coherent anti-Stokes Raman scattering spectroscopy based on fiber optical parametric oscillator and amplifier utilizing four wave mixing in photonic crystal fibers. The output powers and spectra of generated signals were analyzed in detail for various regimes involving spontaneous, stimulated, and amplified parametric processes. The optical parametric oscillator provided tunable signal pulses from 780 to 787 nm with a spectral bandwidth of 3.0 nm, which were then used to seed a fiber optical parametric amplifier, resulting in signal pulses with an average power of 33 mW and spectral bandwidth of 1.1 nm. Using the amplified signal and residual pump pulses, the anti-Stokes signal of polystyrene sample was detected, which confirms the feasibility of the proposed coherent anti-Stokes Raman Scattering light source.

A new consecutive energy calibration method for X/γ detectors based on energy continuously tunable laser Compton scattering light source

In this paper, we present an energy calibration method based on steep Compton edges of the laser Compton scattered (LCS) photon energy spectra. It performs consecutive energy calibration in the neighborhood of certain energy, hence improves calibration precision in the energy region. It can also achieve direct calibration at high energy region (several MeV) where detectors can only be calibrated by extrapolation in conventional methods. These make it suitable for detectors that need wide-range energy calibration with high precision. The effects of systematic uncertainties on accuracy of this calibration method are studied by simulation, using the design parameters of a LCS device—SINAP III. The results show that the SINAP III device is able to perform energy calibration work over the energy region of 25–740 keV. The precision of calibration is better than 1.6% from 25 to 300 keV and is better than 0.5% from 300 to 740 keV.

Rapidly tunable and compact coherent Raman scattering light source for molecular spectroscopy

AbstractWe present a rapidly tunable (over 400 cm − 1) and compact (0.7 m 2 footprint) coherent Raman scattering light source performing both coherent anti‐Stokes Raman scattering and stimulated Raman scattering microspectroscopy. We use spectral focusing of a femtosecond Ti:Sapphire pulse and a redshifted soliton generated in a photonic crystal fiber to reach suitable spectral resolution and to rapidly acquire spectra by means of a delay line translation. The coherent Raman scattering light source is used to monitor the molecular equilibrium shift between hydrogen phosphate and dihydrogen phosphate ions under pH change. Copyright © 2014 John Wiley & Sons, Ltd.

Van de Graaf-based 13.5 nm inverse-Compton light source

We review the factors governing the performance of inverse-Compton light sources in the extreme-ultraviolet (EUV) region. While the use of an optical storage cavity and the minimization of the laser pump focal spot area remain critical to the optimization of power and brightness in the EUV, the appearance of a strong space charge forces at the low electron energies required for operation in the EUV sets an independent lower limit to the focal spot area, and therefore an upper limit to source power and brightness. These limitations are at least partially compensated by the very high average electron currents realizable at these lower electron energies. Based on these considerations, we describe the design and estimated performance of an EUV inverse-Compton scattering light source optimized for average power output and brightness consistent with the limits imposed by the capabilities of existing materials, laser pumps, and radio frequency power sources.