Total Reflection Prism Research Articles

全反射棱镜式激光陀螺自适应稳频技术

全反射棱镜式激光陀螺自适应稳频技术

全反射棱镜式激光陀螺稳频特性研究

全反射棱镜式激光陀螺稳频特性研究

全反射棱镜式激光陀螺双纵模稳频技术

全反射棱镜式激光陀螺双纵模稳频技术

Mid-Infrared Pulsed Laser Lithotripsy with a Tunable Laser Using Difference-Frequency Generation

A novel technique of lithotripsy was investigated with a mid-infrared tunable pulsed laser using difference-frequency generation (DFG). Human gallstone samples obtained from 24 patients were analyzed with their infrared absorption spectra. It was found that the principal components of the gallstones were different for the different patients and that the gallstone samples used in this research could be classified into four groups, i.e., mixed stones, calcium bilirubinate stones, cholesterol stones, and calcium carbonate stones. In addition, some gallstone samples had different compositions within the single stone. The mid-infrared laser tunable within a wavelength range of 5.5 - 10 μm was irradiated to the cholesterol stones at two different wavelengths of 6.83 and 6.03 μm, where the cholesterol stones had relatively strong and weak absorption peaks, respectively. As the result, the cholesterol stones were more efficiently ablated at the wavelength of 6.83 μm with the strong absorption peak. Therefore, it is suggested that the gallstones could be efficiently ablated by tuning the wavelength of the laser to the strong absorption peak of the gallstones. The higher efficiency of the ablation using the characteristic absorption peaks should lead to the safer treatment without damage to the surrounding normal tissues. In order to identify the composition of the gallstones in the patients, endoscopic and spectroscopic diagnosis using the DFG laser and an optical fiber probe made with two hollow optical fibers and a diamond attenuation total reflection prism should be useful. The absorption spectrum of the gallstones in the patients could be measured by measuring the energy of the DFG laser transmitted through the optical fiber probe and by scanning the wavelength of the DFG laser.

谐振腔应力对全反射棱镜式激光陀螺输出光强分布特性影响

谐振腔应力对全反射棱镜式激光陀螺输出光强分布特性影响

Direct excitation of the Tamm plasmon-polaritons on a dielectric Bragg reflector coated with a metal film

AbstractTamm plasmon-polariton is a surface state or surface wave formed at the boundary between a metal and a dielectric Bragg reflector. In order to directly excite the Tamm plasmon-polaritons with unit transmission, we design a structure of Bragg reflector coated with a metal film. Through the Bloch theorem of periodic structures and transfer matrix method, we deduce the existence conditions of the Tamm plasmon-polaritons. For a a finite structure, the Tamm plasmon-polaritons can be excited, which is dependent on the thickness of metal, the period number of the Bragg reflector, the incident direction and frequency. On proper conditions, a perfect transmission for the Tamm plasmon-polariton mode can be achieved without the use of attenuated total reflection prism coupling or diffraction grating.

全反射棱镜式环形激光器合光输出及陀螺精度特性分析

全反射棱镜式环形激光器合光输出及陀螺精度特性分析

Correction of Baseline Drifts due to the Pressure Changes between Attenuated Total Reflection Prism and Human Skin for Noninvasive Blood Glucose Sensing with Fourier Transform Infrared Spectroscopy

.For noninvasive blood sensing with attenuated total reflection (ATR)-Fourier Transform infrared spectroscopy(FTIR), the baseline of spectra human skin will drift because of the exitence of pressure changes between ATR prism and human skin . To correct the baseline drifts ,In the paper, the fingertips spectra in mid-infrared were recorded under the special conditions. A line equation was calculated using the last 14 spectra coupled with the linear regression analysis between the absorbance spectra at the 1035cm-1and the 950cm-1. And the corrected absorption intensities, after the removal of the baseline drifts, can be applied for the quantification of glucose concentrations in blood easily with the given method in the paper.

Evidence of Light Depolarization in Grazing Incidence Germanium Attenuated Total Reflection Prisms

Attenuated total reflection (ATR) infrared absorption spectroscopy is a well-known vibrational spectroscopy technique for many different applications. In recent years this technique has been used to detect thin layer(s) lying on a solid substrate. Such a sample needs high pressure to ensure good optical contact between sample and prism and a p-polarization to enhance the signal to be detected. Such conditions have not been detailed in the literature regarding the effect of high pressure on the ATR measurement. This study shows the detrimental effect of high pressure on the ATR spectra. This effect is related to light depolarization induced by the germanium prism under high pressure. Moreover, the importance of polarizer position in the optical bench is highlighted. Indeed, due to the pressure-induced depolarization of the prism, the polarizer has to be placed before the prism to limit undesirable effects on the ATR spectrum baseline.

Surface plasmon-induced enhancement of the magneto-optical Kerr effect in magnetoplasmonic heterostructures

We developed a self-consistent analytical approach to describe the optical response of a magnetoplasmonic heterostructure upon surface plasmon polariton (SPP) excitation. The approach is based on the effective susceptibility concept in the frame of the Green’s function method and accounts for the local-field effects in the system. The formalism was applied to describe the polar Kerr effect in magnetoplasmonic bilayers consisting of Co and Au on an attenuated total reflection prism. It is demonstrated that the excitation of the SPP in the plasmonic film can lead to an enhancement of the Kerr effect. Analysis performed for the s- and p-polarized incident radiation showed that the enhancement of the Kerr effect is of resonant character, and it is observed when the incident angle of the probing light is close to the angles of the SPP excitation. Thickness-dependent study revealed that the largest enhancement of the Kerr effect is observed for rather thin magnetic layers in the range of couple of nanometers.

A Novel Method for Heightening Sensitivity of Prism Coupler-Based SPR Sensor

We present a novel method for heightening the sensitivity of a prism coupler-based surface plasmon resonance (SPR) sensor. The method is based on the total reflection prism made of BK7 glass combined with the Kretschmann geometry of theattenuated total reflection (ATR) method. Compared to the conventional methods of prism coupler-based SPR, the novel method provides higher sensitivity to the measurement system. Theoretical simulations show that the detection sensitivity to the refractive index (RI) of the sensor based on the novel approach has a strong dependence on the thickness of the metal layer. The RI resolution of the sensor is predicted to be 8 × 10−7 refractive index units (RIU) under the condition of optimum metal film thickness. This novel method can leave out a precision angle rotation device in the angle modulation and it is unnecessary to adjust the acceptance angle of the light detector. The principal advantage of this method over other methods of light intensity modulation based on prism coupler-based SPR is high sensitivity, expediency to measure and application of long distances.

Infrared Laser Therapy using IR absorption of biomolecules

Since numerous characteristic absorption lines caused by molecular vibration exist in the mid-infrared (MIR) wavelength region, selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules. By applying this feature to the medical fields, less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers. A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation (DFG) between a Nd:YAG and a tunable Cr:forsterite lasers. The MIR-DFG laser was tunable in a wavelength range of 5.5–10 μm and generated a laser pulses with an energy of up to 1.4 mJ, a pulse width of 5 ns, and a pulse repetition rate of 10 Hz. Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75 μm, which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions. We have developed a non-destructive diagnostic probe with an attenuated total reflection (ATR) prism and two hollow optical fibres. An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser, and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.

Peptide Route Functionalization of ZnSe Crystals Preserves Activity and Structure of Proteins while Adsorption

Despite the current fast development of materials science, preserving activity and native structure of biomolecules upon their adsorption on a solid substrate is still a challenge in the elaboration of hybrid functional materials. We describe a novel functionalization method of the Zinc Selenide (ZnSe) semiconductor with a peptide presenting surface recognition properties for this material. The peptide was further used as a linker and interface layer when horseradish peroxidase (HRP) was adsorbed onto the ZnSe surface. Our ELISA assays evidenced that HRP activity was enhanced 2-fold when adsorbed on ZnSe via use of the specific peptide compared to when it was directly adsorbed onto the bare surface or the one modified by a polyelectrolyte film. We demonstrate that the secondary structure of the enzyme in its adsorbed form is much closer to its native secondary structure found in solution when peptide functionalization of ZnSe crystal was performed prior to HRP adsorption. The affinity of the peptide for the ZnSe was quantified via force spectroscopy measurements performed with atomic force microscopy and the binding forces between this peptide and the ZnSe were measured to be 125 ± 30 pN. Our results demonstrate the outstanding utility of the specific peptide in surface modification of ZnSe thus avoiding protein denaturation while adsorption. This may be of great interest in triggering biological applications of ZnSe based devices (diodes, attenuated total reflection crystals, prisms, and quantum dots) where interaction with biomolecules is expected.

LESS-INVASIVE LASER THERAPY AND DIAGNOSIS USING A TABLETOP MID-INFRARED TUNABLE LASER

Since numerous characteristic absorption lines caused by molecular vibration exist in the mid-infrared (MIR) wavelength region, selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules. By applying this feature to the medical fields, less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers. A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation (DFG) between a Nd:YAG and a tunable Cr:forsterite lasers. The MIR-DFG laser was tunable in a wavelength range of 5.5–10 μm and generated laser pulses with energy of up to 1.4 mJ, a pulse width of 5 ns, and a pulse repetition rate of 10 Hz. Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75 μm, which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions. We have developed a non-destructive diagnostic probe with an attenuated total reflection (ATR) prism and two hollow optical fibers. An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser, and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.

Investigation of vibrotactile sensation of human fingerpads by observation of contact zones

An experimental apparatus has been developed to observe the contact zones between human fingerpads and a smooth flat surface of a total-reflection prism. Using this apparatus, the following experiments have been carried out: (1) measurement of the apparent and real contact areas of fingerpads under a controlled contact load, (2) measurement of the vibrotactile thresholds of fingerpads under a controlled contact load, and (3) investigation of the discrimination of tones by tactile sensation under a controlled contact load. From the third experiment, it is found that human fingerpads can discriminate between tones from the differences in their harmonic components.

A Novel Method for Enhancing Goos–Hänchen Shift in Total Internal Reflection

Due to the tiny shift in order of optical wavelength for Goos–Hänchen (GH) shift, it is very difficult to directly measure and apply the GH shift. We develop a new method for enhancing GH shift of both TE and TM polarized waves. The method is based on a total reflection prism made of BK9 glass combined with a precise measurement of the resulting spatial displacement with a one-dimensional charge coupled device (CCD). Measurements are performed to examine the validity of the method. Experimental and theoretical results indicate the feasibility of the method with an enhancement in optical wavelenghth shift at millimetre scale. The method is advantageous to application the GH shift in the optical domain, and is also meaningful for measuring even smaller changes in the refractive index of a liquid.

Real time measurement of photochemical surface reactions by using a total reflection prism

ABSTRACTThe photochemical reaction processes, i.e., photo-dissociation of a reaction solution, defluorination of fluorocarbon [FEP], and substitution of a hydrophilic group, were measured in real time, when irradiating a Xe2 excimer lamplight on the water or ammonia solution as a reaction solution and FEP placed on the attenuated total reflectance [ATR] prism. In case of ammonia solution, with the increase in irradiation time, the absorption peaks of 3300 cm−1 and 1650 cm−1 gradually decreased, and the new absorption of -CF2-NH2 gradually appeared at 1410 cm−1, which presented the strongest absorption after UV irradiation for 25 minutes. The results indicate that the ammonia water has turned to amino groups. In addition, the contact angle of water was measured. When compared to the untreated sample, whose contact angle was 110 degrees, the contact angle of the sample treated with water became 31 degrees after the Xe2 lamp irradiation for 25 minutes, and that of the sample modified by ammonia water further improved to 27 degrees after the irradiation for 25 minutes.

Attenuated total reflection Fourier transform infrared spectroscopy of redox transitions in photosynthetic reaction centers: comparison of perfusion- and light-induced difference spectra

Chemically induced Fourier transform infrared difference spectra associated with redox transitions of several primary electron donors and acceptors in photosynthetic reaction centers (RCs) have been compared with the light-induced FTIR difference spectra involving the same cofactors. The RCs are deposited on an attenuated total reflection (ATR) prism and form a film that is enclosed in a flow cell. Redox transitions in the film of RCs can be repetitively induced either by perfusion of buffers poised at different redox potentials or by illumination. The perfusion-induced ATR-FTIR difference spectra for the oxidation of the primary electron donor P in the RCs of the purple bacteria Rb. sphaeroides and Rp. viridis and P700 in the photosystem I of Synechocystis 6803, as well as the Q A −/Q A transition of the quinone acceptor (Q A) in Rb. sphaeroides RCs are reported for the first time. They are compared with the light-induced ATR-FTIR difference spectra P +Q A −/PQ A for the RCs of Rb. sphaeroides and P700 +/P700 for photosystem 1. It is shown that the perfusion-induced and light-induced ATR-FTIR difference spectra recorded on the same RC film display identical signal to noise ratios when they are measured under comparable conditions. The ATR-FTIR difference spectra are very similar to the equivalent FTIR difference spectra previously recorded upon photochemical or electrochemical excitation of these RCs in the more conventional transmission mode. The ATR-FTIR technique requires a smaller amount of sample compared with transmission FTIR and allows precise control of the aqueous environment of the RC films.

3-D orientation and switching studies of FLCs using ATR FTIR spectroscopy

Three different alignments of FLC molecules at the surfaces of attenuated total reflection (ATR) prisms are used for investigating the switching and the 3-D orientations of FLC molecules. ATR FTIR study for a depth of a penetration of ∼1.2 μmUm shows that the reorientation of molecules within a thin layer for vibrational bands is the same as for the bulk sample. A 3-D ATR study of FLC cell shows that the rotation of molecules around the long molecular axis is biased.

Extended-spectral-range Fourier transform infrared-attenuated total reflection spectroscopy on Si surfaces using a novel Si coated Ge attenuated total reflection prism

We show that it is possible to extend the lower limit of the spectral range of Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy on Si surfaces from 1500 to ∼850 cm−1 using a Ge ATR prism coated with a thin epitaxial layer of Si, making accessible the especially important fingerprint region of organic molecules. The utility of the ATR prism is demonstrated by collecting FTIR spectra of several surface terminations of Si (H, oxide, 3-aminopropyltrimethoxysilane, and DNA) that contain peaks in the newly accessible spectral region.