共查询到20条相似文献,搜索用时 31 毫秒
1.
Yukihiro Ishii 《Optics and Lasers in Engineering》1991,14(4-5):293-309
Laser-diode (LD) interferometry based on heterodyne techniques is described. The developments covered include: sinusoidal phase- modulating, distance-measuring feedback and phase-shifting interferometry. The wavelength is controlled by the laser injection current and is continuously or stepwise changed to introduce a time-varying phase difference between the two beams of an interferometer with unbalanced optical path lengths. A feedback interferometer is described with electronics to stabilize the phase shift and to lock the interferometer on a preset phase condition by controlling the injection current of the LD. An automated phase-measuring interferometric system is developed in which the laser current is changed to synchronize intensity data acquisition with the clocks of a charge-coupled device. A typical experimental result shows measurements of the profile of a diamond- turned Al surface. 相似文献
2.
We describe fiber-based quadrature low-coherence interferometers that exploit the inherent phase shifts of 3 x 3 and higher-order fiber-optic couplers. We present a framework based on conservation of energy to account for the interferometric shifts in 3 x 3 interferometers, and we demonstrate that the resulting interferometers provide the entire complex interferometric signal instantaneously in homodyne and heterodyne systems. In heterodyne detection we demonstrate the capability for extraction of the magnitude and sign of Doppler shifts from the complex data. In homodyne detection we show the detection of subwavelength sample motion. N x N (N > 2) low-coherence interferometer topologies will be useful in Doppler optical coherence tomography (OCT), optical coherence microscopy, Fourier-domain OCT, optical frequency domain reflectometry, and phase-referenced interferometry. 相似文献
3.
一种探测光纤BSBS温敏效应的新方法黄民双(长沙铁道学院长沙410075)刘邦群(武汉大学物理学系武汉430072)ANewDetectionMethodofOpticalFiberThermalySensitiveEfectusingBSBSAbs... 相似文献
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Raman heterodyne detection is a coherent optical-RF double resonance technique where the optical and RF fields induce coherence within a three level system and a resultant Raman field is measured using heterodyne detection. This approach has been used previously to detect NMR and more recently EPR. In this paper the parameters that affect the amplitude and signal to noise ratio of the Raman heterodyne signals are considered. The power levels in relation to the oscillator strength and dephasing times, the amplitude and spectrum of the laser frequency jitter in relation to the optical homogeneous linewidths and holeburning rates, and the sample properties such as absorption strength and optical quality, are all factors that affect the Raman signal. The presentation is focused on the Raman heterodyne detected EPR of the nitrogen-vacancy pair centre in diamond making comparisons with Raman heterodyne detected NMR signals obtained for rare earth ion systems. RF-RF double resonance studies, RF holeburning and ENDOR, which give information about the hyperfine levels are also reported for the nitrogen-vacancy centre. The resonance frequencies are in agreement with those predicted from the spin Hamiltonian. The factors affecting the lineshapes and relative intensities of the double resonance signals are discussed. 相似文献
6.
Self-sustained oscillations in a laser optical fibre heterodyne interferometer are discussed; oscillations were produced by closing into a loop the single-mode optical fibres of the interferometer. Such oscillatory systems are shown to feature high-frequency stability. It is proposed to use this oscillating interferometer as a high-sensitivity sensor of external factors affecting the optical waveguide. 相似文献
7.
便携式空间外差拉曼光谱仪集成了光学功能镜头、干涉仪组件,以及探测器和激光器等热辐射器件,因此仪器在使用过程中存在着较为复杂的热环境,环境温度变化导致光学系统性能下降。采用光机热集成分析方法,重点研究了环境温度及热辐射器件对关键器件成像镜头的性能影响。在便携式空间外差拉曼光谱仪光学和结构方案设计的基础上,建立热-结构耦合模型;仿真得到成像功能镜头内镜片的间距和面形的变化,并利用Zernike多项式拟合其变化;将拟合结果代入光学设计软件中进行成像质量评估和分析。结果表明,在使用环境温度(-10℃~40℃)范围内,调制传递函数在光谱仪截止频率76.9 lp/mm处对比度均优于0.38,满足便携式空间外差拉曼光谱仪的使用要求。 相似文献
8.
K. Orsel E. T. Garbacik M. Jurna J. P. Korterik C. Otto J. L. Herek H. L. Offerhaus 《Journal of Raman spectroscopy : JRS》2010,41(12):1678-1681
We demonstrate a new technique that combines polarization sensitivity of the coherent anti‐Stokes Raman scattering (CARS) response with heterodyne amplification for background‐free detection of CARS signals. In this heterodyne interferometric polarization CARS (HIP‐CARS), the major drawbacks of polarization and heterodyne CARS are rectified. Using a home‐built picosecond optical parametric oscillator, we are able to address vibrational stretches between 600 and 1650 cm−1 and record continuous high‐resolution Raman equivalent HIP‐CARS spectra. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
9.
B. J. Rye 《Optical and Quantum Electronics》1979,11(5):441-446
The concept of the reference range, a parameter used to characterize the ranging capability of radar systems, is applied to atmospheric backscatter lidar employing direct detection and optical heterodyne receivers. Use of the reference range is suggested for system evaluation in this area. 相似文献
10.
This paper evaluates the coherent optical code-division multiple-access (OCDMA) techniques and examines the overall system
performance in terms of signal-to-noise ratio (SNR) penalty as a function of simultaneous users accommodated to maintain an
appropriate value of the bit-error rate (BER) for homodyne and heterodyne detections. As spreading codes, the proposed structures
are utilizing a recently introduced prime code family hereby referred to as double-padded modified prime code (DPMPC). As
a coherent modulation, binary phase-shift keying (BPSK) format is deployed. In homodyne detection, two different phase modulations
are studied including either an external phase-modulator or injection-locking methods. The phase limitation and the performance
for two methods plus multiple-access interferences (MAI) and receiver noise in a shot-noise limited regime are investigated.
In heterodyne detection, BER analysis of the system based on only external phase modulator is examined. It is found that by
maintaining BER = 10−9, this system can accommodate an increased number of simultaneous users to compare with systems which employ conventional
bipolar codes. 相似文献
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12.
Shinn-Fwu Wang 《Optics and Lasers in Engineering》2009,47(10):1039-1043
In this paper, an optical fiber sensor based on multiple total internal reflections (MTIRs) in heterodyne interferometry is proposed. With the optical fiber sensor the phase shift difference due to the multiple total internal reflections effect between the p- and s-polarizations is measured by using heterodyne interferometry. Substituting the phase shift difference into Fresnel's equations, the refractive index for the tested medium can be calculated. The resolution of the sensor can reach 1.6×10?6 refractive index unit (RIU). The optical fiber sensor could be valuable for chemical, biological and biochemical sensing. It has some merits, such as, high resolution and stability, high sensitivity, high resolution and real-time measurement. 相似文献
13.
Ting-Chung Poon Kyu B. Doh Bradley Schilling Kazunori Shinoda Yoshiji Suzuki Ming Hsien Wu 《Optical Review》1997,4(5):567-571
Three-dimensional (3-D) or holographic information extracted by two-dimensional active optical heterodyne scanning has been demonstrated recently. The technique is called optical scanning holography. To reconstruct the obtainable 3-D holographic information, digital techniques have been used and demonstrated. For real-time applications, we need to investigate spatial-light-modulator-based systems. In this paper, we first briefly review optical scanning holography, and then present experimental results of 3-D image reconstruction using an electron-beam-addressed spatial light modulator. 相似文献
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This paper proposes an optical method for measuring small displacements using the surface plasmon resonance (SPR) heterodyne interferometry. A heterodyne light beam reflected by a mirror passes through a hemisphere glass and then enters into a surface plasmon resonance apparatus at the resonant angle. A small displacement of the mirror will introduce a phase-difference variation between p- and s-polarizations of the light emerging from the SPR apparatus. The phase-difference variation can be precisely measured with the heterodyne interferometric technique, and the associated displacement can be estimated. The feasibility of this method was verified by experiment, and the displacement measurement resolution of about 1.4 nm over a traveling range of 6 μm was achieved. Our method of measurement has the merits of both common-path interferometry and heterodyne interferometry. 相似文献
16.
Optimal interferometer designs for optical coherence tomography 总被引:2,自引:0,他引:2
We introduce a family of power-conserving fiber-optic interferometer designs for low-coherence reflectometry that use optical circulators, unbalanced couplers, and (or) balanced heterodyne detection. Simple design equations for optimization of the signal-to-noise ratio of the interferometers are expressed in terms of relevant signal and noise sources and measurable system parameters. We use the equations to evaluate the expected performance of the new configurations compared with that of the standard Michelson interferometer that is commonly used in optical coherence tomography (OCT) systems. The analysis indicates that improved sensitivity is expected for all the new interferometer designs, compared with the sensitivity of the standard OCT interferometer, under high-speed imaging conditions. 相似文献
17.
Bitou Y 《Optics letters》2003,28(17):1576-1578
A digital phase-shifting interferometer with a liquid-crystal-display coupled, parallel aligned, nematic liquid-crystal spatial light modulator is developed. The optical phase shift in the Michelson-type polarization interferometer is achieved by a digital phase shift of a grating displayed on the spatial light modulator. Accurate experimental results of using the heterodyne system for pi/2 phase steps were demonstrated. A phase-shifting interferometer with no moving parts and no requirement for calibration of the value of the phase shift was achieved. 相似文献
18.
Various optical coherent transient signals in ruby have been examined by using an optical phase sensitive detection (PSD) technique. The PSD is performed by comparing the phase of the heterodyne beat signals obtained by the Stark switching technique with that of a local oscillator whose frequency is equal to the heterodyne beat frequency. The optical FID, two-pulse photon echoes, radiation locked echoes and notched echoes have been detected as υ-mode signals with small u-mode signals probably due to the asymmetry of the inhomogeneous broadening. The dependence of the phase of the radiation locked and notched echoes upon the driving pulses is also examined. The experimental results are in good agreement with theoretical predictions based on Bloch equations. 相似文献
19.
All-fiber digital heterodyne interferometry is a laser metrology technique employing pseudo-random codes phase modulated onto
an optical carrier signal. In this heterodyne interferometer system, the optical signal includes signal reflected and transmitted
from the sample, respectively. Compared with the conventional heterodyne interferometry, this enhanced optical system has
much higher measurement sensitivity, and can distinguish the signal which reflected from the front and the rear surface of
the sample. Analysis and simulation for the digital heterodyne interferometry are presented. It takes approximately 4 s to
scan the whole surface with the diameter of 300 mm. The thickness profile of the sample is obtained in the experiment. The
discussion about the experiment is given finally. 相似文献
20.
本文提出的光外差调制法用于提高空间解调低相干光纤传感器峰顶位置的分辨率,由此提高系统的测量灵敏度.未采用光外差调制法前的杨氏空间解调低相干光纤位移传感器的测量灵敏度为0.12μm;而采用后可达0.033μm. 相似文献