Raman Microprobe with Holographic Beamsplitter for Low-Frequency Operation

1992 ◽  
Vol 46 (10) ◽  
pp. 1469-1473 ◽  
Author(s):  
David M. Pallister ◽  
Kei-Lee Liu ◽  
Anurag Govil ◽  
Michael D. Morris ◽  
Harry Owen ◽  
...  
Keyword(s):  
Low Frequency ◽  
Transmission Efficiency ◽  
Exciting Line ◽  
Raman Microprobe ◽  
Anti Stokes

A Raman microprobe with a holographic beamsplitter is described. The beamsplitter is shown to have 90% laser insertion efficiency and high Raman transmission efficiency on both the Stokes and anti-Stokes side. Useful spectra are obtainable as close as ±60 cm−1 from the exciting line using 4 mW power.

Low-frequency multiplex CARS microscopy with a high-repetition near-infrared supercontinuum laser

2021 ◽  
Author(s):  
Yusuke Arashida ◽  
Atsushi Taninaka ◽  
Takayuki Ochiai ◽  
Hiroyuki Mogi ◽  
Shoji YOSHIDA ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
High Sensitivity ◽  
High Repetition ◽  
Spectrum Shaping ◽  
Crystal Phase Transition ◽  
Wavenumber Region ◽  
Anti Stokes

Abstract We have developed a multiplex Coherent anti-Stokes Raman scattering (CARS) microscope effective for low-wavenumber measurement by combining a high-repetition supercontinuum light source of 1064 nm and an infrared high-sensitivity InGaAs diode array. This system could observe the low-wavenumber region down to 55 cm-1 with high sensitivity. In addition, using spectrum shaping and spectrum modulation techniques, we simultaneously realized a wide bandwidth (<1800 cm-1), high wavenumber resolution (9 cm-1), high efficiency, and increasing signal to noise ratio by reducing the effect of the background shape in low-wavenumber region. Spatial variation of a sulfur crystal phase transition with metastable states was visualized.

Enhanced transmission efficiency of magneto-inductive wave propagating in non-homogeneous 2-D magnetic metamaterial array

2022 ◽  
Author(s):  
Thi Hong Hiep Le ◽  
Thanh Son Pham ◽  
Bui Xuan Khuyen ◽  
Bui Son Tung ◽  
Quang Minh Ngo ◽  
...  
Keyword(s):  
Near Field ◽  
Low Frequency ◽  
Transmission Efficiency ◽  
Position Sensor ◽  
Wireless Power ◽  
Current Ratio ◽  
Enhanced Transmission ◽  
Unit Cells ◽  
Simulation And Experiment ◽  
Ratio Transmission

Abstract In this work, we investigate the propagation of magneto-inductive waves (MIWs) in ordering magnetic metamaterial (MM) structures. The proposed non-homogeneous MM slab consists of 9 × 9 MM unit cells constructed from a five-turn spiral embedded on an FR-4 substrate. External capacitors with the value of 40 pF or 50 pF were added to control the resonant frequency of each unit cell in accordance with the waveguide configurations. The characteristics of metamaterial structures, such as negative permeability, current ratio, transmission response, and field distribution in the waveguide, have been thoroughly analyzed by simulation and experiment. Because of the strong magnetic field confinement in the waveguide, the transmittance after nine elements of the non-homogeneous MM slab is 5.2 times greater than that of the homogeneous MM slab. This structure can be applied to the planar near-field wireless power transfer, position sensor, and low-frequency communication.

scholarly journals A Simple Calibration Method of Anti-Stokes–Stokes Raman Intensity Ratios Using the Water Spectrum for Intracellular Temperature Measurements

2020 ◽  
Vol 74 (10) ◽  
pp. 1295-1296
Author(s):  
Yuki Yoshikawa ◽  
Shinsuke Shigeto
Keyword(s):  
Raman Spectrum ◽  
Low Frequency ◽  
Practical Method ◽  
Calibration Method ◽  
Temperature Measurements ◽  
Raman Shift ◽  
Acquisition Time ◽  
Boltzmann Factor ◽  
Intensity Ratios ◽  
Anti Stokes

Presented here is a facile and practical method for calibrating anti-Stokes–Stokes intensity ratios in low-frequency Raman spectra that is devised specifically for temperature measurements inside cells. The proposed method uses as an intensity standard the low-frequency Raman spectrum of liquid water, a major molecular component of cells, whose temperature is independently measured with a thermocouple. Rather than calibrating pixel intensities themselves, we obtain a correction factor at each Raman shift in the 20–200 cm−1 region by dividing the anti-Stokes–Stokes intensity ratio calculated theoretically from the Boltzmann factor at the known temperature by that obtained experimentally. The validity of the correction curve so obtained is confirmed by measuring water at other temperatures. The anti-Stokes–Stokes intensity ratios that have been subjected to our calibration are well fitted with the Boltzmann factor within ∼1% errors and yield water temperatures in fairly good agreement with the thermocouple temperature (an average difference ∼1 ℃). The present method requires only 15 min of spectral acquisition time for calibration, which is 50 times shorter than that in a recently reported calibration method using the pure rotational Raman spectrum of N2. We envision that it will be an effective asset in Raman thermometry and its applications to cellular thermogenesis and thermoregulation.

scholarly journals High-speed low-frequency chirped coherent anti-Stokes Raman scattering microscopy using an ultra-steep long-pass filter

2019 ◽  
Vol 27 (24) ◽  
pp. 35993
Author(s):  
Liqing Ren ◽  
Dekel Raanan ◽  
Ilan Hurwitz ◽  
Dan Oron
Keyword(s):  
Raman Scattering ◽  
High Speed ◽  
Low Frequency ◽  
Pass Filter ◽  
Anti Stokes

scholarly journals Magnetic Pendulum Arrays for Efficient ULF Transmission

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Srinivas Prasad M N ◽  
Rustu Umut Tok ◽  
Foad Fereidoony ◽  
Yuanxun Ethan Wang ◽  
Rui Zhu ◽  
...  
Keyword(s):  
Quality Factor ◽  
Free Space ◽  
Low Frequency ◽  
Transmission Efficiency ◽  
Experimental Results ◽  
Proof Of Concept ◽  
Electrically Small Antennas ◽  
Fundamental Limits ◽  
Small Antennas ◽  
Order Of Magnitude

Abstract The frequencies lying between 300 Hz to 3 kHz have been designated as Ultra Low Frequency (ULF) with corresponding wavelengths from 1000 Km to 100 Km. Although ULF has very low bandwidth it is very reliable, penetrating and difficult to jam which makes it a great choice for communication in underwater and underground environments. Small and portable ULF antennas within a diameter of 1 meter would operate under an electrical length on the order of 10−4 to 10−6 wavelengths in free space, making them very inefficient because of fundamental limits on radiation from electrically small antennas. To overcome this problem, Mechanical Antennas or ‘Mechtennas’ for Ultra Low Frequency Communications have been proposed recently. For efficient generation of ULF radiation, we propose a portable electromechanical system called a Magnetic Pendulum Array (MPA). A proof of concept demonstration of the system at 1.03 kHz is presented. The theory and experimental results demonstrate that such a system can achieve a significantly higher quality factor than conventional coils and thus order of magnitude higher transmission efficiency. The concept can be easily scaled to the ULF range of frequencies.

Near IR multichannel Raman spectroscopy with μm spatial resolution

1992 ◽  
Vol 50 (2) ◽  
pp. 1500-1501
Author(s):  
J. Barbillat ◽  
B. Roussel
Keyword(s):  
Spatial Resolution ◽  
Near Infrared ◽  
Low Frequency ◽  
Diffraction Limit ◽  
Small Samples ◽  
Optical Elements ◽  
Near Ir ◽  
Photodiode Arrays ◽  
Silicon Based ◽  
Anti Stokes

The techniques and capabilities of near infrared (NIR) multichannel microprobing are described in detail in this paper.The advantages and drawbacks of various kinds of instruments used to measure Raman spectra excited in the NIR spectral range have been extensively studied and compared. We demonstrate that a dispersive spectrometer specially designed to match the recently improved NIR multichannel detectors (silicon-based CCD,Germanium and InGaAs photodiode arrays) may provide better results than a Fourier Transform Interferometer in two fields:- spatial resolution close to the diffraction limit in a micro-Raman confocal configuration (1.5 to 2 μm) and- extension of the Raman spectrum to the low-frequency region (Stokes and Anti-Stokes).Moreover, to observe the excitation profiles of both resonance and fluorescence, a combined multichannel instrument covering the entire range from 0.4 to 1.5 μm enables the user to select the best conditions of measurement.For the study of very small samples (close to the diffraction limit),it is optically impossible to fill in the wide entrance aperture of the interferometer with the image of the sample while covering correctly the optical elements inside the interferometer.

Low-Frequency Raman Spectra Using Synchronously Scanned Optical Parametric Oscillator CARS

1997 ◽  
Vol 51 (11) ◽  
pp. 1678-1681
Author(s):  
Peter C. Chen ◽  
Michon Pinnix
Keyword(s):  
Optical Parametric Oscillator ◽  
Rayleigh Scattering ◽  
Low Frequency ◽  
Parametric Oscillator ◽  
Stray Light ◽  
Raman Signal ◽  
Optical Parametric ◽  
A New Technique ◽  
Wavelength Detection ◽  
Anti Stokes

Synchronously scanned optical parametric oscillator (OPO) coherent anti-Stokes Raman spectroscopy (CARS) is a new technique that can be used with single-wavelength detection in order to reject background stray light and eliminate spectral interference. In this paper, results are presented illustrating the use of this method to also reject stray light from Rayleigh scattering without attenuation of the Raman signal, resulting in the ability to probe low-frequency Raman levels.

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