Along with rapid development of semiconductor, photodetector arrays (e.g. CCD) have offered the great promise of compact Optical Multichannel Analyzer (OMA) for spectrum fast measurements in a variety of applications. It deserves to pay attention to frequency response of electronic circuit in OMA, otherwise it will impair the spectrum resolving power of the analyzer. In this paper, we present a detailed frequency analysis of electronic circuit in OMA, and find that the frequency response should be met a severe condition, in which the cutoff frequency is much higher than the output frequency of photodetector arrays, to guarantee the resolution performing well in OMA.
The research of the optical level gauge is to realize its use in oil tank. Its fundamental structure and principle of operation are introduced, especially the technique of double light paths is adopted in order to avoid the influence caused by temperature and the bending resulted from installing and own weight. The experimental set-up and measured data of 40m alignment experiment, the basic experiment using cube corner retroreflector(CCR) and experiment using single wavelength coupler are respectively presented. Some adjustment problems of optical path are analyzed and resolved. It is proved that the selections of single-mode and multimode fibers are suitable through experiments. The right method of optical design is given through experiments and analysis, which effectively reduces the demand for linearity of CCR in moving, that is, to extend the effective diameter of receiving light spot as possible. Finally, the further improvement of optical design-using polarized light and further reducing diameter of CCR are presented in order to easily mount the device on the tank on the basis of the above researches.
The design proposals of active alignment system suitable for different transmission ranges are presented. Influence of light power distribution on the focal plane ofthe receiver on complexity of a alignment system is analyzed, The optical system ofthe lasercom system is not used in imaging, but transmitting signals, and so the optical design method of the suitable power distribution of the light spot on the focal plane of the receiver should be adopted in the design of whole optical system from transmitter to receiver in order to reduce the bad influence due to the spot shifting on signal transmitting.
This paper presents design of a multichannel spectrophotometer, which uses a holographic concave grating as dispersive element. The flat spectral field of the grating generates the integration of collimation, disperse and convergence. Meanwhile, a CCD with 2048 pixels is placed on the spectral plane as a multichannel photodetectors so that the system can eliminate mechanical scanning. Due to the features of those elements and design procedure, the spectrophotometer shows more advantages that the structure of the new typed spectrometer becomes smaller, its stability, reproducibility and the rate of measurement have been much more increased.
An active three dimension imaging laser a radar based on phase comparison technique, using an amplitude modulation cw laser diode source was established, its optical scanning system consisting of a nodding mirror and a 4-facet polygon rotor is analyzed in detail, 3D image sampling systems with real time range nonlinear calibration, light intensity-phase compensator and RS422 standard sending interface was realized. The 3D laser radar had demonstrated successfully and reliably in field test of autonomous land vehicle.
A new electro-optic modulator is designed and constructed. It is suitable for maintaining modulation at a high frequency and can be used to generate ultra-wide-sideband signals to form ultrashort optical
pulses. In experiments, phase modulation with a modulation index of 57 rad is successfully obtained at 16.25 GHz, and thereby optical sidebands extending over widths as wide as 1.85 THz are attained. The sidebands
produced are broad enough to form subpicosecond pulses using the chirping-compression method.
A new structure electrooptic modulator is designed and constructed. It is suitable for deep modulation at high frequency and can be used to generate ultrawide sideband signals for forming ultrashort optical pulses. In experiments, phase modulation with a modulation index of 57 rad has been successfully obtained at 16.25 GHz, and thereby optical sidebands extending over as wide as 1.85 THz have been attained. The sidebands produced are broad enough to form subpicosecond pulses using the chirping-compression method.
In the report, we explain how the quasi-velocity-matched electrooptic (EO) modulator using domain inversion can generate extreme wide sideband. The quasi-matching between the phase velocity of microwave and the group velocity of light was established by using periodic domain inversion of an EO crystal LiTaO3 at a frequency of 9.35 GHz. Long effective interaction length was also obtained at such a high modulation frequency. As a result, we obtained modulation index 22.5 rad and extended the sidebands up to 420 GHz.
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