Showing papers by "Edward S. Fry published in 2000"
TL;DR: This comment on that paper disputes the claims that (1) their list of references on pure water absorption is complete, (2) their result "...provides reliable data in the 320-420-nm region...," and (3) their data agree well with existingData in the literature.
Abstract: Measurements of the absorption of pure water have been described [Appl. Opt. 38, 1216 (1999)]. This comment on that paper disputes the claims that (1) their list of references on pure water absorption is complete, (2) their result "...provides reliable data in the 320-420-nm region...," and (3) their data agree well with existing data in the literature. The clearest demonstration of these points is made by plotting their data and its associated error bars together with plots of other data in the literature that should be considered significantly more reliable. Finally, for practical applications that require absorption data, a suggestion is made for the best choice of absorption coefficients in the range of 196 nm
46 citations
TL;DR: In this paper, the double-dark scheme of four-level atomic coherence was used to obtain strong laser gain in the ultra-violet and vacuum ultraviolet, and a new technique for eliminating Doppler broadening in a large class of multi-level schemes was presented.
28 citations
TL;DR: In this paper, the authors present recent advances in fundamental tests of quantum mechanics, particularly those involving entangled Einstein-Podolsky-Rosen (EPR) pairs, and provide an extensive review of an experiment based on photodissociation of the dimer 199 Hg2.
Abstract: Publisher Summary This chapter presents recent advances in fundamental tests of quantum mechanics, particularly those involving entangled Einstein-Podolsky-Rosen (EPR) pairs. Quantum mechanics predicts that the total spin of this two-particle system is zero, and for measurements of both components in one specific direction, it predicts that the results will be opposite with unit probability.It briefly mentions the latest down-conversion experiments and also concentrates. The chapter discusses the first atomic entanglement in the micromaser; and provides an extensive review of an experiment based on photodissociation of the dimer 199 Hg2 on the atom-based tests. The isotope 199 Hg has nuclear spin I = 1/2, and those molecules in a state with total nuclear spin I = 0 are selected. In addition, it is an exact experimental realization of Bohm's well-known version of the EPR gedankenexperiment. This experiment can test the Bell inequalities in a regime very different from those using photons.
22 citations
TL;DR: The Integrating Cavity Absorption Meter (ICAM) as mentioned in this paper was developed to measure the separate contributions to the spectral absorption coefficient due to a pure liquid, due to particles suspended in it, and due to the substances dissolved in it.
19 citations
TL;DR: The measurements of the absorption spectrum of pure water in a paper by Pope and Fry have been criticized by Quickenden et al.
Abstract: The measurements of the absorption spectrum of pure water in a
paper by Pope and Fry [Appl. Opt.36, 8710 (1997)]
have been criticized by Quickenden et al. [Appl. Opt.39, 2740 (2000)]. These criticisms are
answered.
9 citations
Patent•
26 Jan 2000TL;DR: In this paper, a system for underwater object detection using an optical signal generator and an absorption cell was proposed. But the system was not designed for underwater applications. And it was not shown that the absence of a portion of the shifted frequency component of the optical signal caused the detection of an underwater object.
Abstract: A system for detecting an underwater object includes an optical signal generator operable to generate and transmit an optical signal into the water. The system also includes an absorption cell operable to receive the optical signal reflected from the water and absorb an unshifted frequency component of the reflected optical signal. The system further includes a detector operable to receive a shifted frequency component of the optical signal from the absorption cell and detect the object using the shifted frequency component of the optical signal. Displacement of the water by the object causes an absence of a portion of the shifted frequency component of the optical signal.
7 citations
TL;DR: The modulation in the spectrum generated by the windows of a Pockels cell is discussed, where the residual reflectivity of the highly parallel window faces can still have etalon effects that lead to pronounced spectrum modulation.
Abstract: We discuss the modulation in the spectrum generated by the windows of a Pockels cell. Although they are antireflection coated, the residual reflectivity of the highly parallel window faces can still have etalon effects that lead to pronounced spectrum modulation. This problem is easily solved by the use of slightly wedged windows.
2 citations
07 May 2000
TL;DR: In this article, the beam of a low power seed source is gated with an electro-optic gate and then consecutively amplified first by a high gain fiber amplifier (up to 60 dB gain) followed by four-passing through a bulk amplifier.
Abstract: Summary form only given.Laser sources with energies in the microjoule to millijoule range are used in a multitude of applications. Many applications require narrow linewidth and tunability. The traditional approach employed is to use a low power, narrow linewidth master laser to injection seed a high power slave oscillator. In order for the oscillator to operate at the seeder frequency the cavity of the former has to be resonant with the seeder mode. Two alternative approaches are currently employed to achieve this goal: (1) the minimization of the build-up time or (2) the ramp-fire technique, in which the Q-switch is fired, when a resonance is detected while one cavity mirror is ramped rapidly. An alternative approach is presented. The beam of a low power seed source is gated with an electro-optic gate and then consecutively amplified first by a high gain fiber amplifier (up to 60 dB gain) followed by four-passing through a bulk amplifier. In contrast to a Q-switched fiber laser, our configuration does not form a closed cavity and no resonance condition must be fulfilled.
1 citations
07 May 2000
TL;DR: In this article, an edge detector based on iodine absorption lines has been implemented in a lab to obtain the first measurements, to the best of our knowledge, of the temperature dependence of the sound speed in fresh water.
Abstract: Summary form only given. The edge technique is a powerful method for measuring small frequency variations such as the Brillouin shifts of an ocean backscattering signal from a pulsed laser. Besides yielding a direct measurement of the speed of sound in the ocean, an edge technique has obvious advantages over the heterodyne techniques, which are based on devices such as interference filters or Fabry-Perots, including a much higher solid angle of acceptance and relative insensitivity to mechanical instability and environmental variations. One model of this edge detector based on iodine (/sup 129/I/sub 2/) absorption lines has been implemented in our lab to obtain the first measurements, to our knowledge, of the temperature dependence of the sound speed in fresh water. We provide an illustration of the detection apparatus to measure sound speed (temperature) based on the Brillouin Lidar return. Our laser system is a modified Continuum PowerLite Nd:YAG, which provides 1 joule of pulse energy at 532 nm.
1 citations
01 Mar 2000
TL;DR: In this paper, the beam of a low power seed source is gated with an electro-optic gate and then consecutively amplified first by a high gain fiber amplifier (up to 60 dB gain) followed by four-passing through a bulk amplifier.
Abstract: Summary form only given.Laser sources with energies in the microjoule to millijoule range are used in a multitude of applications. Many applications require narrow linewidth and tunability. The traditional approach employed is to use a low power, narrow linewidth master laser to injection seed a high power slave oscillator. In order for the oscillator to operate at the seeder frequency the cavity of the former has to be resonant with the seeder mode. Two alternative approaches are currently employed to achieve this goal: (1) the minimization of the build-up time or (2) the ramp-fire technique, in which the Q-switch is fired, when a resonance is detected while one cavity mirror is ramped rapidly. An alternative approach is presented. The beam of a low power seed source is gated with an electro-optic gate and then consecutively amplified first by a high gain fiber amplifier (up to 60 dB gain) followed by four-passing through a bulk amplifier. In contrast to a Q-switched fiber laser, our configuration does not form a closed cavity and no resonance condition must be fulfilled.