89 results about "Fourth harmonic" patented technology

An optically pumped semiconductor laser includes an active ring-resonator having two or more optically pumped semiconductor (OPS) structures each including a mirror-structure and a multilayer gain-structure. The mirror-structures serve as fold mirrors for the resonator axis. An optically nonlinear crystal may be included in the ring-resonator for generating second-harmonic radiation from fundamental radiation generated in the resonator. Another optically nonlinear crystal may be provided for generating third-harmonic or fourth-harmonic radiation from the second-harmonic radiation. In one example, including a third-harmonic generating crystal, a passive ring-resonator partially coaxial with the active ring-resonator is provided for circulating second-harmonic radiation to provide resonant amplification of the second-harmonic radiation for enhancing third-harmonic conversion. Apparatus for automatically maintaining the passive ring-resonator in a resonant condition for the second-harmonic radiation is disclosed.

The present invention provides a radiation source apparatus which can generate a DUV radiation beam having a wavelength of 193.4 nm efficiently. The radiation source apparatus according to the invention has first wavelength conversion means arranged to receive a first laser beam of a first fundamental wavelength and to generate a fourth-harmonic wavelength of the first fundamental wavelength, second wavelength conversion means arranged to receive the beam of the fourth-harmonic wavelength of the first fundamental wavelength (266 nm) and a second laser beam of a second fundamental wavelength and to sum-frequency mix the fourth-harmonic with the second fundamental wavelength radiation to generate a beam of second DUV radiation having a wavelength between approximately 232 nm and 237 nm, and third wavelength conversion means arranged to receive the beam of second DUV radiation and the third laser beam of a third fundamental wavelength and to sum-frequency mix the second DUV radiation with the third fundamental wavelength radiation to generate third DUV radiation having a wavelength between approximately 192.5 nm and 194.5 nm.

A method of correcting for phasefront aberrations in ultrasound imaging uses highly spaced apart point scatterers artificially placed in the tissue being imaged. The point scatterers reflect the transmitted sound and are individually differentiated to provide singular reference points for correction of signals reflected from the surrounding tissue. The differentiation is performed by comparison of the third or fourth harmonic frequencies of the reflected signals. To ensure the necessary high dispersal of the point scatterers, high amplitude pulses of the transmitted signal destroy point scatterers in selected image regions. In an alternate embodiment, correction is performed by stochastic analysis of signals reflected from the highly dispersed point scatterers. A reference signal is compared to the second harmonic of the reflected signal to reduce noise.

A radio frequency (“RF”) harmonic filter circuit as disclosed herein is fabricated using integrated passive device (“IPD”) technology. The RF harmonic filter circuit is configured to provide second, third, and fourth harmonic rejection while providing good input and output impedance matching. The RF harmonic filter circuit employs only one IPD loop inductance (preferably used for a second harmonic resonance circuit), which results in a significant die/package size reduction. The RF harmonic filter circuit also employs a combined circuit that performs input and/or output impedance matching and third harmonic rejection.

The present invention is to provide an optical modulating system for generating a signal of a frequency (f₀+2f_m) and a signal of a frequency (f₀−2f_m) and suppressing a signal of a frequency (f₀) by a DSB-SC modulator.

A fourth harmonic generating system for solving the above problem comprises a first DSB-SC modulator (2) a second DSB-SC modulator (3) and a signal control section (5) for controlling a modulating signal from a signal source (4) for generating modulating signals applied to the first and second DSB-SC modulators (2,3) so that a lower side-band signal (f₀) generated by modulating the upper side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) and an upper side-band signal (f₀) generated by modulating the lower side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) cancel each other.

In order to generate efficiently a deep ultraviolet laser beam having a wavelength in a deep ultraviolet region and to make the generated laser beam to be high output, it is arranged in such that a laser beam having about 227 nm wavelength is generated by sum-frequency mixing of fourth harmonic of the laser beams obtained by amplifying semiconductor laser beams having 1064.0 to 1065.0 nm wavelengths by means of an optical fiber amplifier, and the laser beams obtained by amplifying semiconductor laser beams having 1557.0 to 1571.0 nm wavelengths by means of another optical fiber amplifier; and further laser beams having 198.4 to 198.7 nm wavelengths are generated by sum-frequency mixing of the above sum-frequency mixed laser beam and the above-described semiconductor laser beams having 1557.0 to 1571.0 nm wavelengths.

The invention discloses a control method for suppressing modularized multi-level current transformer output current harmonic wave. At first, the modularized multi-level output current is detected, a second harmonic component, a third harmonic component, and a fourth harmonic component or above are obtained by a Fourier analysis method and then are compared with 0, and the modulated voltage components of suppressed harmonic wave via a generalized frequency division PI regulator and are added to the modulated component under voltage stabilization control and the modulated component of the output voltage to obtain a total modulated voltage. After the total modulated voltage is obtained, the modulation is carried out by means of a closest level approximation method to obtain modularized multi-level current transformer triggering pulse. By means of the harmonic compensation scheme, the harmonic components, after being detected, of the output current are superposed to a control system through negative feedback, so that the output harmonic wave of the modularized multi-level current transformer can be directly and effectively suppressed.

A laser system is enabled to generate laser beam stably for a long term by avoiding the decay of nonlinear optical crystals due to moisture. The fundamental laser wave at a wavelength of 1064 nm is emitted from the pumping chamber unit of the solid-state laser device. The fundamental laser wave enters the first nonlinear optical crystal unit (20). The wavelength of the laser beam is converted into a half by the first nonlinear optical crystal unit (20). The converted laser beam emanates out of the unit. The fundamental laser wave and the second harmonic laser wave are introduced into the second nonlinear optical crystal unit. Each of the laser beams is converted into the third harmonic laser wave (three-time fundamental frequency) or the fourth harmonic laser beam (four-time fundamental frequency) and the laser beam comes out of the exit-window (34). The nonlinear optical crystal units (20), (30) are held in a hermetically sealed cell whose inner surface is treated to be water-repellent. As the dry atmosphere is kept by means of isolating the nonlinear optical crystal from the outer air, the crystals can avoid decay due to moisture and the damage on the crystals can be reduced.

The invention discloses a six-axis robot which comprises a base, a rotating base, supporting big arms, shoulder joints, supporting small arms, wrist joints and a terminal end actuator, wherein a first servo motor is fixedly arranged in the inner cavity in the base, a first harmonic speed reducer is arranged on the lower end of the inner cavity of the rotating base, a second servo motor is fixedly arranged on the upper end of the inner cavity of the rotating base, a second harmonic speed reducer and a third harmonic speed reducer are arranged on the inner cavities of the supporting big arms, a third servo motor and a fourth servo motor are fixedly arranged on the inner cavities of the shoulder joints, a first belt wheel is fixedly connected to the output shaft of the fourth servo motor, a fifth servo motor, a fourth harmonic speed reducer and a fifth harmonic speed reducer are arranged on the inner cavities of the supporting small arms, a second belt wheel is fixedly connected to a soft wheel of the fourth harmonic speed reducer, the second belt wheel is in transmission connection with the first belt wheel through a first synchronization belt, a sixth servo motor and a sixth harmonic speed reducer are arranged on the inner cavities of the wrist joints, and the terminal actuator is fixedly connected with the soft wheel of the sixth harmonic speed reducer. The six-axis robot is good in flexibility and fast in action.

A permanent-magnet rotary electric machine preferably includes a stator and a rotor opposed thereto via an air gap. The stator includes a stator core having 4m (m is an integer equal to or larger than 2) main poles each having inductor teeth at a tip thereof. The rotor includes two rotor units adjacent to each other in the axial direction. Each rotor unit includes a pair of rotor magnetic poles and a permanent magnet arranged therebetween. The permanent magnets in the rotor are axially magnetized in opposite directions to each other. Each rotor magnetic pole has magnetic teeth on its outer periphery at a regular pitch. The rotor magnetic poles in each rotor unit are arranged such that the magnetic teeth of one rotor magnetic plate are offset by half a pitch from those of the other rotor magnetic pole, and the magnetic teeth of adjacent rotor magnetic poles are aligned with each other in the axial direction. The tooth pitch of the inductor teeth of each stator main pole is different from that of the magnetic teeth of the rotor magnetic pole to generate a fourth harmonic component of a permeance between the stator and the rotor zero.

The invention relates to an optical quadruple frequency millimeter wave optical carrier wireless communication system which comprises a center station, a base station and a downlink fiber. The center station and the base station are in fiber connection through a down link. The center station comprises a laser, a double-electrode Mach-Zehnder optical modulator and an erbium doped fiber amplifier which are in series connection in order. The double-electrode Mach-Zehnder optical modulator is used for generating a fourth harmonic side frequency component containing a cosine microwave signal, and carrying OFDM-16QAM data information. The base station is used for receiving the fourth harmonic side frequency component containing the cosine microwave signal and carried OFDM-16QAM data information, and through carrying out bias set, filtering and amplification on the received signal, a millimeter wave signal of OFDM-16QAM modulation for antenna emission is obtained. The system in the invention has the characteristics of simple structure, easy realization and low cost.

The invention relates to measurement of the modulation degree and the initial phase of sinusoidal phase modulating interference measurement. The object of the invention is to propose a method for overcoming the defect of complicated measuring process of the modulation degree in the sinusoidal phase modulating interference measurement, the method is simple and feasible, and the calculated modulation degree value avoids errors in the principle. According to the technical scheme, the measurement method of the modulation degree and the initial phase of sinusoidal phase modulating interference measurement includes: light splitting of light beams emitted by a laser is performed by employing a light-splitting apparatus to construct a Michelson interferometer, and sine modulation is performed on an interference phase by employing an external modulation technology or an internal modulation technology; and a photoelectric conversion module receives modulated Michelson interference signals, the Michelson interference signals are input to a signal processing module after analog-to-digital conversion, a fourth harmonic amplitude is extracted, and the modulation degree and the initial phase are solved through calculation. The method is mainly applicable to occasions of modulation interference measurement.