Controlling Light Intensity Patents (Class 372/29.014)
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Patent number: 7345513Abstract: A driver circuit is provided, which includes a differential amplifier whose output signal controls the driving input signal, a reference signal generator that supplies a reference input of the differential amplifier, an external feedback that applies a signal, which is dependent on the output signal, to a feedback input of the differential amplifier, an adapter circuit, and an internal feedback activated in a compensation mode as an alternative to the external feedback, which internal feedback provides a signal to both the feedback input and the adapter circuit even for input signals that do not exceed the first threshold. The adaptor circuit generates and stores a compensation signal that compensates an offset signal acting alone at the reference input when the reference signal generator is switched off, and feeds the stored compensation signal, together with a reference signal, to the reference input or feedback input when the external feedback is activated.Type: GrantFiled: November 23, 2005Date of Patent: March 18, 2008Assignee: Atmel Germany GmbHInventors: Karl-Josef Gropper, Herbert Knotz, Michael Offenwanger, Armin Prohaska
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Patent number: 7336685Abstract: YAG laser can simultaneously emit a plurality of laser beams having different wavelengths from each other. By simultaneously irradiating the laser beams having different wavelengths from each other to a same region of a non-single crystal semiconductor film, an interference influence is suppressed to obtain a more uniform laser beam. For example, by simultaneously generating second and third harmonics of YAG laser to irradiate the same region through suitable optical system, a laser beam having higher uniformity and having an energy in which interference is highly suppressed is obtained.Type: GrantFiled: January 14, 2004Date of Patent: February 26, 2008Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Koichiro Tanaka
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Patent number: 7298977Abstract: The present invention is intended to prevent a light-emitting diode from emitting light continuously in the case when the level at an input terminal is fixed high because of software or the like and to avoid various problems, such as battery exhaustion and breakdown of the light-emitting diode, in PDAs, cellular phones, etc. For these purposes, a high-pass filter 21 for passing the high-frequency components of an optical transmission input signal having a pulse waveform and a binary circuit 22 for binarizing the output signal of the high-pass filter 21 so as to be returned to a pulse waveform are provided in the preceding stage of a light-emitting device driving circuit 23 for driving a light-emitting diode 8 for optical transmission.Type: GrantFiled: November 28, 2002Date of Patent: November 20, 2007Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Katsuichi Ohsawa, Toyoyuki Shimazaki, Tetsuo Chato, Yuzo Shimizu, Kenji Imaizumi
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Publication number: 20070263683Abstract: An optical apparatus includes a light source for emitting laser light perpendicularly to a surface of a semiconductor substrate; a positioning member for positioning the light source; an aperture stop defining an opening for limiting transmission of laser light emitted from the light source; a light detection member, provided on or close to the positioning member, for detecting an intensity of laser light; a reflection member, provided on the aperture stop, for reflecting the laser light from the light source toward the light detection member; and an adjusting means for adjusting an intensity of laser light emitted from the light source on the basis of a detection result of the light detection member.Type: ApplicationFiled: May 7, 2007Publication date: November 15, 2007Applicant: CANON KABUSHIKI KAISHAInventor: Hiroshi NAKAHATA
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Patent number: 7294816Abstract: A light source and method for controlling the same. The light source includes a first component light source that includes N LEDs, a photo-detector, and a collector, where N>1. Each LED has a light emitting chip in a package. The light emitting chip emits light in a forward direction and light in a side direction. The light generated in the forward direction is determined by a drive signal coupled to that LED. A portion of the light in the side direction leaves the package. The collector is positioned such that a portion of the light in the side direction that leaves the package of each of the LEDs is directed onto the photo-detector. The photo-detector generates N intensity signals, each intensity signal having an amplitude related to the intensity of the light emitted in the side direction by a corresponding one of the LEDs.Type: GrantFiled: December 19, 2003Date of Patent: November 13, 2007Assignee: Avago Technologies ECBU IP (Singapore) Pte. Ltd.Inventors: Fook Chuin Ng, Kee Yean Ng, Heng Yow Cheng
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Patent number: 7282706Abstract: The present invention is directed to a novel arrangement of optical devices for the rapid patterning of laser profiles used for desorption and/or ionization sources in analytical mass spectrometry. Specifically, the new optical arrangement provides for a user-defined laser pattern at the sample target that can be quickly changed (on a microsecond timescale) to different dimensions (or shapes) for subsequent laser firings.Type: GrantFiled: February 11, 2005Date of Patent: October 16, 2007Assignee: The Texas A&M University SystemInventors: David H. Russell, John A. McLean
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Publication number: 20070223544Abstract: This laser processing apparatus includes an amp fiber, a seed laser oscillating unit, a fiber core exciting unit, a laser emitting unit, a controlling unit, a light sensor, etc. A Q-switched pulse seed laser beam from the seed oscillating unit enters into one end surface of the amp fiber, and a continuously oscillated core excitation light from the fiber core exciting unit 14 enters into the other end surface. The seed laser beam is amplified in the activated core during the propagation through the amp fiber and comes out as a high-power processing laser beam from the other end surface of the amp fiber. The light sensor 64 feeds back the laser power of the processing laser beam to the seed laser oscillating unit.Type: ApplicationFiled: March 20, 2007Publication date: September 27, 2007Inventors: Nobuyuki Yamazaki, Kazunori Sakae
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Publication number: 20070047602Abstract: The present invention provides an LD driver able to stably control the output power and the extinction ratio of the optical signal without regarding the coupling mode, the AC mode or the DC mode, between the laser diode and the LD driver. The LD driver includes the peak hold and the bottom hold, each detecting the peak level or the bottom level of the monitored signal, respectively. The bias driver adjusts the bias current so as to equalize the peak level of the monitored signal to the reference, REF_PEAK, while, the modulation driver adjusts the modulation current so as to equalize the bottom level of the monitored signal to the reference, REF_BOTTOM. In the present invention, the adjustment of the modulation current by the modulation driver starts with a substantial delay with respect to the stabilization of the bias current by the bias driver.Type: ApplicationFiled: August 23, 2006Publication date: March 1, 2007Applicant: Sumitomo Electric Industries, Ltd.Inventors: Keiji Tanaka, Katsumi Uesaka
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Patent number: 7184614Abstract: A method and apparatus are disclosed for improving bodily safety during exposure to an eye hazardous monochromatic treatment light source by diverging the light, such as with a diffusing unit attached to the light source distal end so that the radiance of the light exiting the distal end is an eye safe level. At a first position of the light source distal end substantially in contact with an outer surface of a target, the energy density of an exit beam from the distal end is suitable for effecting a desired treatment, and at a second non-contact position of the distal end the exit beam energy density is significantly less than a value suitable for effecting the treatment. In an additional embodiment, the diverging or diffusing unit has a device for evacuating vapors or particles from the target.Type: GrantFiled: July 7, 2003Date of Patent: February 27, 2007Assignee: Inolase 2002 Ltd.Inventor: Michael Slatkine
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Patent number: 7139295Abstract: A system for tuning the wavelength of a beam from a tunable laser. A tunable etalon assembly includes a Fabry-Perot etalon with paired reflectors to filter the laser beam. The tunable etalon also includes a thermal unit to thermally adjust the separation of the paired responsive to an etalon tuning signal. A photodetector receives the laser beam after filtering the etalon and generates a detected signal based on intensity. A controller generates the etalon tuning signal, and receives the detected signal and generates a laser tuning signal based on it. Optionally, additional Fabry-Perot etalons, photodetectors, and one or more beamsplitters permit extending wavelength range and determining relative wavelength difference with a beam from a second laser.Type: GrantFiled: January 27, 2004Date of Patent: November 21, 2006Assignee: Fibera, Inc.Inventors: John C. Tsai, David W. Wang
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Patent number: 7123844Abstract: In optical filter systems and optical transmission systems, an optical filter compresses data into and/or derives data from a light signal. The filter way weight an incident light signal by wavelength over a predetermined wavelength range according to a predetermined function so that the filter performs the dot product of the light signal and the function.Type: GrantFiled: January 25, 2002Date of Patent: October 17, 2006Inventor: Michael L. Myrick
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Publication number: 20060222025Abstract: A laser module includes a semiconductor laser, an output optical system provided on an optical output side of the semiconductor laser, a temperature detecting element that detects a temperature of the output optical system; and an output controller that calculates a drive current to set an optical output intensity of the laser module at a desired value on the basis of temperature information obtained by the temperature detecting element, and outputs the drive current to the semiconductor laser.Type: ApplicationFiled: March 30, 2006Publication date: October 5, 2006Applicant: EUDYNA DEVICES INC.Inventors: Haruyoshi Ono, Isao Baba
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Patent number: 7095762Abstract: An object of the present invention is obtaining a semiconductor film with uniform characteristics by improving irradiation variations of the semiconductor film. The irradiation variations are generated due to scanning while irradiating with a linear laser beam of the pulse emission. At a laser crystallization step of irradiating a semiconductor film with a laser light, a continuous light emission excimer laser emission device is used as a laser light source. For example, in a method of fabricating an active matrix type liquid crystal display device, a continuous light emission excimer laser beam is irradiated to a semiconductor film, which is processed to be a linear shape, while scanning in a vertical direction to the linear direction. Therefore, more uniform crystallization can be performed because irradiation marks can be avoided by a conventional pulse laser.Type: GrantFiled: July 26, 2005Date of Patent: August 22, 2006Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Koichiro Tanaka
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Patent number: 7095763Abstract: An improved laser-based wafer carrier mapping sensor is provided. The sensor includes a number of improvements including laser source improvements; optical improvements; and detector improvements. Laser source improvements include the type of laser sources used as well as the specification of size and power of such sources. Optical improvements include features that intentionally defocus the laser stripe on the wafer as well as additional features that help ensure precision stripe generation. Detector improvements include increasing gain while decreasing the effects of ambient light. Various combinations of these features provide additional synergies that facilitate the construction of a sensor with significantly improved dynamic response while decreasing the frequency of false cross slot errors.Type: GrantFiled: December 16, 2002Date of Patent: August 22, 2006Assignee: CyberOptics Semiconductor, Inc.Inventor: Felix J. Schuda
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Patent number: 7075956Abstract: An optical semiconductor device comprises: an optical semiconductor element; and a circuit. The circuit is connected to the optical semiconductor element and has a series rectifying circuit including a plurality of zener diodes connected in series. The circuit further has a rectifying element whose anode is connected to an anode of the series rectifying circuit.Type: GrantFiled: August 27, 2003Date of Patent: July 11, 2006Assignee: Kabushiki Kaisha ToshibaInventor: Masaru Numano
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Patent number: 7065111Abstract: Systems, methods and computer software are provided for testing a laser. Initially, the laser is operated at a first bias setting and a data rate of about 10 Gb/s, and a first side mode suppression ratio of the laser output is measured that is based on a first ratio of a highest and next highest optical power peaks as a function of a first wavelength. Next, the laser is operated at a second bias setting and a data rate of about 10 Gb/s, and a second side mode suppression ratio of the laser output is measured that is based on a second ratio of a highest and next highest optical power peaks as a function of a second wavelength. A test result for the laser is then generated in accordance with a difference between the first and second side mode suppression ratios.Type: GrantFiled: April 14, 2004Date of Patent: June 20, 2006Assignee: Finisar CorporationInventor: Charles W. Miller
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Publication number: 20060098700Abstract: The invention relates to a method and laser device for producing a high optical power density by forming laser bars (LB) of diode lasers (E) in a manner that in a single laser bar (LB) the slow axes (x) of adjacent diode lasers (E) are positioned relative to each other in the same line and said diode lasers (E) emit substantially to the same direction (z), and radiation emitted by said plurality of laser bar (LB) is further collected to a combined and bright beam that is parallel with the optical axis (A). In accordance with the invention the laser bars (LB) are arranged in sectors relative to the optical axis (A) to an axial symmetrical structure in a manner that the direction of beams leaving from different sectors is turned (DE) in order to combine said beams. Preferred embodiments of the invention enable combination of efficient sector-by-sector radiation of laser bars (LB) using spatial, polarisation and/or wavelength multiplexing.Type: ApplicationFiled: May 20, 2003Publication date: May 11, 2006Applicant: Oseir OyInventors: Taito Alahautala, Erkki Lassila
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Publication number: 20060088071Abstract: A method, apparatus and system for controlling operation of a laser driver to limit emission levels of laser diodes each producing different monitor photocurrents are disclosed. In one embodiment, a laser driver controller includes a control signal generator configured to generate a single control signal to concurrently regulate an average power of the emission levels to a target average power level, and to generate a monitored output power reference to determine whether an output power of the emission levels exceeds an output power limit. The control signal generator can more accurately limit the emission levels than if the monitored output power reference is adjusted independent of regulating the average power.Type: ApplicationFiled: October 20, 2005Publication date: April 27, 2006Inventor: Ka'ren Hovakimyan
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Patent number: 7024864Abstract: An adjustable bipolar current source for a load, such as a thermoelectric cooler, includes a voltage-controlled power supply having a unipolar output, and an H-bridge. At least one of the two active elements on a first side and at least one of the two active elements on a second side of the H-bridge comprises an active conductive element responsive to a control signal to set a magnitude of current flow through the active conductive element. Control logic provides the control signals to the active elements on the first and second sides to set the polarity of the current to the load. Logic coupled to the voltage-controlled power supply maintains a supply voltage sufficient to maintain a voltage drop across the active conductive elements within a linear range of operation of the conductive elements. The output of the voltage-controlled power supply is clamped at or near a minimum stable level.Type: GrantFiled: December 3, 2002Date of Patent: April 11, 2006Inventor: Anthony J. Alfrey
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Patent number: 7002128Abstract: The invention relates to a feedback loop for a laser diode driving circuit for ensuring that the laser diode generates optical power at a constant safe level. The feedback loop includes a monitor diode, which generates a monitor current Imon, and a set resistance for generating a set voltage based on the monitor current and the set resistance. The set voltage is compared with a reference voltage in an operational amplifier, which generates a control signal for controlling the laser diode current source. The laser diode current source dictates the amount of bias current transmitted to the laser diode. Safety features, in the form of voltage comparators, are provided to ensure that: a) the feedback loop is closed, i.e. Imon is not too low; b) the optical power is not above standard safety threshold, i.e. Imon is not too high; and c) the monitor diode voltage is sufficient to provide specified optical power to electrical power conversion.Type: GrantFiled: August 14, 2003Date of Patent: February 21, 2006Assignee: JDS Uniphase CorporationInventors: Daniel Scott Hedin, Matthew James Paschal
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Patent number: 6989520Abstract: There is provided an emission control apparatus with which it is capable of variably controlling the intensity of a light beam to be set, in a stable manner and at a low cost without increasing the circuit size. A semiconductor laser diode LD emits a light beam. A photo diode PD detects the intensity of the light beam emitted from the semiconductor laser diode LD. A driving circuit supplies driving current to the semiconductor laser diode LD. A switching section switches the driving current according to a video signal. An input terminal receives a pulse width modulation signal. A smoothing circuit smoothes the received pulse width modulation signal. A laser driver controls a value of the driving current according to smoothed voltage obtained by the smoothing circuit such that the detected intensity of the light beam is equal to a target intensity.Type: GrantFiled: April 11, 2003Date of Patent: January 24, 2006Assignee: Canon Kabushiki KaishaInventors: Masataka Mochiduki, Yasuhiro Tomioka
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Patent number: 6975813Abstract: Using a switching signal from a coarse/fine switching and operation mode switching circuit, the width of change of a counter control value during power up is increased, and the width of change is reduced once a steady state is reached. In the steady state, the frequency of updating is limited by a control signal from an update permit control circuit. In the steady state, the frequency band of a current source in an LD driving circuit is reduced in width.Type: GrantFiled: February 17, 2000Date of Patent: December 13, 2005Assignee: Fujitsu LimitedInventors: Tadao Inoue, Tadashi Ikeuchi, Hiroyuki Rokugawa, Masaaki Kawai, Norio Ueno, Norio Murakami, Toru Matsuyama, Makoto Miki, Toshiyuki Takauji
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Publication number: 20050271097Abstract: An object of the present invention is obtaining a semiconductor film with uniform characteristics by improving irradiation variations of the semiconductor film. The irradiation variations are generated due to scanning while irradiating with a linear laser beam of the pulse emission. At a laser crystallization step of irradiating a semiconductor film with a laser light, a continuous light emission excimer laser emission device is used as a laser light source. For example, in a method of fabricating an active matrix type liquid crystal display device, a continuous light emission excimer laser beam is irradiated to a semiconductor film, which is processed to be a linear shape, while scanning in a vertical direction to the linear direction. Therefore, more uniform crystallization can be performed because irradiation marks can be avoided by a conventional pulse laser.Type: ApplicationFiled: July 26, 2005Publication date: December 8, 2005Inventors: Shunpei Yamazaki, Koichiro Tanaka
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Patent number: 6944195Abstract: An object of the present invention is obtaining a semiconductor film with uniform characteristics by improving irradiation variations of the semiconductor film. The irradiation variations are generated due to scanning while irradiating with a linear laser beam of the pulse emission. At a laser crystallization step of irradiating a semiconductor film with a laser light, a continuous light emission excimer laser emission device is used as a laser light source. For example, in a method of fabricating an active matrix type liquid crystal display device, a continuous light emission excimer laser beam is irradiated to a semiconductor film, which is processed to be a linear shape, while scanning in a vertical direction to the linear direction. Therefore, more uniform crystallization can be performed because irradiation marks can be avoided by a conventional pulse laser.Type: GrantFiled: December 10, 2002Date of Patent: September 13, 2005Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventors: Shunpei Yamazaki, Koichiro Tanaka
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Publication number: 20050175048Abstract: A method and apparatus are provided to controllably reduce power of a laser projection display (LPD) in response to detecting a variation in a viewing surface. During the operation of the LPD, a controller 142 monitors laser light being reflected from the viewing surface. Since the controller 142 “knows” the amount of power that the LPD is being instructed to deliver, it may compare the known power to the reflected laser light to determine if a foreign object may be in the path of the laser light, and therefore, affecting the magnitude of the laser light. The controller 142 responds to detecting such an event by reducing power to the lasers.Type: ApplicationFiled: April 30, 2004Publication date: August 11, 2005Inventors: Miklos Stern, Paul Dvorkis, Narayan Nambudiri, Carl Wittenberg, Chinh Tan, Ron Goldman, Dmitriy Yavid, Frederick Wood
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Patent number: 6922420Abstract: A workpiece is irradiated by a laser beam scanned in an oscillating track as the workpiece is advanced along a feed path in a hardening process. Sinusoidal variations in scan velocity are offset by decreasing the laser beam power level at phases in the scanning cycles corresponding to high and low scan displacement peaks, where the scan velocity is least. The beam power is increased near the scanning center line where the scan velocity is highest. The beam energy applied per unit of area is thus equalized over the scanning cycle. The workpiece temperature can be sampled at regular phases by a non-contact temperature sensor in the optical path, and used to control beam power versus phase in a subsequent scanning cycle. Alternatively or in addition, a sinusoidal beam power pattern can be stored and used to offset scan velocity variations as a function of phase.Type: GrantFiled: October 25, 2002Date of Patent: July 26, 2005Assignee: Yamazaki Mazak Kabushiki KaishaInventors: Tsunehiko Yamazaki, Naoomi Miyagawa, Toshihiko Inoue, Toshihiko Asari, Masaaru Matsumura
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Publication number: 20050135441Abstract: A light source and method for controlling the same. The light source includes a first component light source that includes N LEDs, a photo-detector, and a collector, where N>1. Each LED has a light emitting chip in a package. The light emitting chip emits light in a forward direction and light in a side direction. The light generated in the forward direction is determined by a drive signal coupled to that LED. A portion of the light in the side direction leaves the package. The collector is positioned such that a portion of the light in the side direction that leaves the package of each of the LEDs is directed onto the photo-detector. The photo-detector generates N intensity signals, each intensity signal having an amplitude related to the intensity of the light emitted in the side direction by a corresponding one of the LEDs.Type: ApplicationFiled: December 19, 2003Publication date: June 23, 2005Inventors: Fook Ng, Kee Ng, Heng Cheng
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Patent number: 6894314Abstract: A power monitoring arrangement for semiconductor light emitting devices used in optoelectronic packages includes a mounting structure, a light emitting device, and a monitor photodetector. The mounting structure has a mounting surface with the light emitting device and the monitor photodetector positioned thereon. The light emitting device provides emitted light at a monitoring output and an active output. The monitor photodetector has a light sensitive region and is positioned on the mounting surface of the mounting structure proximate the monitoring output of the light emitting device. A hemisphere of material is formed to include at least the light sensitive region of the monitor photodetector and the monitoring output of the light emitting device. An outer surface of the hemisphere operates as a reflecting surface to reflect light from the monitoring output of the light emitting device to the light sensitive region of the monitor photodetector.Type: GrantFiled: February 10, 2004Date of Patent: May 17, 2005Inventor: Robert William Musk
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Patent number: 6891866Abstract: A method for determining a condition of the laser system includes determining a change in a laser current from an initial value. A method for measuring a laser current includes determining a difference between the values of a power supply current, which is the value of the laser current. A method for measuring a transmitted power includes generating a first control signal that sets a magnitude of a bias current supplied to a laser, generating a second control signal that sets a of a modulation current supplied to the laser, and determining a difference between values of a high and a low transmitted powers. A method for measuring a received optical power includes determining a received OMA corresponding to the power signal, which is the transmitted OMA minus a known loss through a calibration fiber that couples the laser transmitter to the laser receiver.Type: GrantFiled: January 10, 2003Date of Patent: May 10, 2005Assignee: Agilent Technologies, Inc.Inventors: Michael A. Robinson, Gideon Z. Romm, Randall P. Clark, Frederick W. Miller
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Patent number: 6885684Abstract: A laser control circuit comprises a temperature control circuit and a data processing circuit. The temperature control circuit adjusts the temperature of a laser diode by controlling a temperature regulator. The data processing circuit receives the output of a wavelength monitor. The data processing circuit first adjusts the, temperature of the laser diode to a temperature value previously associated with the target wavelength. Then the data processing circuit finely adjusts the temperature of the laser diode according to the output of the wavelength monitor. Because rough adjustment has been carried out, it is not necessary to change the wavelength significantly according to the output of the wavelength monitor. Therefore, the periodic wavelength dependence of the output of the wavelength monitor does not decrease the accuracy of the control.Type: GrantFiled: April 23, 2003Date of Patent: April 26, 2005Assignee: Sumitomo Electric Industries, Ltd.Inventor: Moriyasu Ichino
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Patent number: 6872913Abstract: A laser unit, which provides markings on a surface of a continuous strip of metal, includes a laser for generating a beam of laser radiation. The laser unit further includes a lens arrangement for focusing the laser beam onto the surface of the strip, and a beam scanner that effects a controlled deflection of the laser beam in two mutually perpendicular directions. The beam scanner is arranged intermediate the laser and the lens arrangement. The laser unit is operable to provide laser engraved markings at exact locations on the surface when the strip intermittently is in an immobilized condition before being fed into a subsequent processing apparatus, which mechanically shapes the thus-marked strip into marked articles to be included in cans.Type: GrantFiled: November 28, 2000Date of Patent: March 29, 2005Assignee: REXAM ABInventor: Manfred Jendick
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Patent number: 6870863Abstract: A laser used in a DWDM optical-fiber application is controlled so that, before it is powered up or down, its output power is maximally attenuated, the result being minimal cross-channel interference due to out-of-spec. wavelength. Laser control is further characterized by the steps of: (a) with laser current at zero, establishing a desired temperature of operation of the laser; (b) with output attenuation at maximum, increasing the current and regulating it to a level at which the design operating wavelength is achieved, and (c) decreasing the attenuation until the desired output power to the optical-fiber link is attained. Maximum attenuation is preferably applied during step (a).Type: GrantFiled: November 29, 1999Date of Patent: March 22, 2005Assignee: Marconi UK Intellectual Property Ltd.Inventors: Graham Butler, Michael Leach
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Patent number: 6827502Abstract: The present invention provides a two VCSEL array mounted in a single can with a monitoring diode. One VCSEL is directed toward the can window (for coupling with an attached fiber optic in a completed subassembly) and the other is directed toward the monitor diode. The two VCSELS are electrically coupled in parallel, are connected to the same pins in the TO can, and are driven by the same source. Preferably the two VCSELS are identical or nearly identical. The current of the monitor diode is proportional to the light emitted by both VCSELs. Since the monitor diode measures incident light from the second VCSEL, no angle of reflection is affected by changes in temperature. Since the two VCSELs are coupled in parallel, the device has a naturally low impedance.Type: GrantFiled: March 6, 2001Date of Patent: December 7, 2004Assignee: Infineon Technologies AGInventor: Stefan J. Burmeister
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Patent number: 6807202Abstract: The invention relates to a method that can be used to compensate the influence of the temperature on the optical output power (light power) of light emitting diodes and laser diodes without the need to measure the temperature or light power. The method is based on the fact that the current flowing through a light emitting or laser diode and the forward voltage drop on the diode are at a constant light power independent of the temperature in a functional correlation that is often linear and can be obtained. If it is known, it must only be achieved during operation that the current and the forward voltage exhibit this correlation in order to eliminate the temperature effect on the light power.Type: GrantFiled: March 17, 2000Date of Patent: October 19, 2004Assignee: Sensor Line-Gesellschaft fuer Optoelektronische Sensoren mbHInventors: Joerg Plamper, Josef Engl
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Publication number: 20040190568Abstract: Systems, methods and computer software are provided for testing a laser. Initially, the laser is operated at a first bias setting and a data rate of about 10 Gb/s, and a first side mode suppression ratio of the laser output is measured that is based on a first ratio of a highest and next highest optical power peaks as a function of a first wavelength. Next, the laser is operated at a second bias setting and a data rate of about 10 Gb/s, and a second side mode suppression ratio of the laser output is measured that is based on a second ratio of a highest and next highest optical power peaks as a function of a second wavelength. A test result for the laser is then generated in accordance with a difference between the first and second side mode suppression ratios.Type: ApplicationFiled: April 14, 2004Publication date: September 30, 2004Inventor: Charles W. Miller
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Patent number: 6795656Abstract: An optical transmission circuit includes: a semiconductor laser; a drive circuit for supplying drive current to the semiconductor laser; a duty changing circuit for changing a duty value of an input data; a converting circuit for supplying a duty control signal to the duty changing circuit in order to adjust the duty value of the input data; and an adjusting circuit for supplying an optical power control signal to the converting circuit and the drive circuit. The adjusting circuit performs an initial setting of an optical power of the semiconductor laser, and the converting circuit performs the initial setting of the duty value so as to have a characteristic opposite to the optical power. According to the above structure, it is possible to realize the duty adjustment and the optical power adjustment by using only one adjusting circuit so that it is possible to achieve a simplified, miniatuarized, and low cost optical transmission circuit.Type: GrantFiled: March 15, 2000Date of Patent: September 21, 2004Assignee: Fujitsu LimitedInventors: Tadashi Ikeuchi, Yuji Tochio, Toshiyuki Takauji
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Patent number: 6778566Abstract: A key requirement of a fiber optic communication system is its ability to transmit data from one location to another relatively free of errors in the data stream. The data stream error rate is a function of the error rate of the laser module utilized to transmit the data. A fast and efficient method of testing a laser module, in order to estimate its bit error rate, is to measure side mode suppression ratios of the laser module output while operating the laser module at each of a first and second bias setting, and to generate a test result for the laser module in accordance with the difference between the first and second side mode suppression ratio measurements. Furthermore, a system is provided for performing this laser module testing method.Type: GrantFiled: September 18, 2002Date of Patent: August 17, 2004Assignee: Finisar CorporationInventor: Charles W. Miller
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Patent number: 6763054Abstract: The optical system includes a stack of lensed, AR-coated laser diode bars and optics to brighten the stack's output. A spatial filter forces each bar to lase in one or a few high-order modes having two strong emission lobes. Radiation in the first lobe is passed to a collimating optic to form a filtered image of each of the lensed diode bars on an associated grating, whose angle then determines the lasing wavelength of that bar. Radiation in the second lobe is directed into an output path where another collimating optic produces an array of spatially separated, collimated beams. The wavelengths set for each beam allow them to be spectrally combined into a single, multi-wavelength, collimated output beam possessing substantially the same cross section and divergence as an individual input beam.Type: GrantFiled: November 19, 2002Date of Patent: July 13, 2004Assignee: The Boeing CompanyInventor: Richard M. Whitley
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Patent number: 6738398Abstract: The invention provides an SHG laser light source whose optical output can be modulated using a simple mechanism without having to equip the light source with an external modulator, and a method of modulation for use with the SHG laser light source, wherein the SHG laser light source comprises a laser diode for outputting a fundamental wave of light, a drive circuit for simultaneously modulating one or more electric currents or voltages supplied to the laser diode to modulate the fundamental wave outputted by the laser diode, and an SHG device which receives the modulated or unmodulated fundamental wave, converts the wavelength thereof, and outputs a second harmonic wave which is intensity modulated.Type: GrantFiled: December 1, 2000Date of Patent: May 18, 2004Assignees: Yokogawa Electric Corporation, Matsushita Electric Industrial Co., Ltd.Inventors: Takaaki Hirata, Shinji Iio, Takeshi Inoue, Yasuo Kitaoka, Kazuhisa Yamamoto
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Patent number: 6731662Abstract: A laser light intensity controller includes a polarizing beam splitter for passing most of one of an x-direction polarization component perpendicular to a direction in which a laser beam emitted from a light source travels and a y-direction polarization component parallel with the traveling direction and for reflecting a little portion of the one polarization component as monitoring light, and a photodetector for receiving the reflected monitoring light to generate a light intensity signal. The controller drives the light source in accordance with the light intensity signal. The photodetector reflects the other of the x-direction polarization component and the y-direction polarization component and is not sensitive thereto, and absorbs the one polarization component and is sensitive thereto.Type: GrantFiled: October 3, 2001Date of Patent: May 4, 2004Assignee: Pioneer CorporationInventors: Naoharu Yanagawa, Fumihiko Sano
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Publication number: 20040066807Abstract: A light source device can attain a stable output of a harmonic even when there occurs a change in the ambient temperature or fluctuation in the output power. The light source device is provided with a semiconductor laser source (4), an optical waveguide-type QPM-SHG device (5) for generating a second harmonic from light emitted from the semiconductor laser source (4), a wavelength control means (7) for controlling a wavelength of light emitted from the semiconductor laser source (4), a means for slightly fluctuating wavelength (8) for changing a wavelength of light emitted from the semiconductor laser source (4) and a means for detecting a change in output light power of the optical waveguide-type QPM-SHG device (5) that occurs when a wavelength of light emitted from the semiconductor laser source (4) is changed.Type: ApplicationFiled: June 26, 2003Publication date: April 8, 2004Inventors: Ken?apos;ichi Kasazumi, yasuo Kitaoka, Tosifumi Yokohama, Kiminori Mizuuchi, Kazuhisa Yamamoto, Hisashi Senga, Shigeru Furumiya, Hiromichi Ishibashi
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Patent number: 6678290Abstract: According to the present invention, an optical output automatic control circuit includes an optical output cutoff control circuit outside its feedback loop, and sets an optical output setting voltage at the ground level to prevent overshoot of the optical output while an optical output cutoff signal is being input.Type: GrantFiled: March 12, 2002Date of Patent: January 13, 2004Assignee: NTT Electronics CorporationInventors: Takeshi Yoshida, Masaki Hirose, Takeshi Inagaki, Katsuhito Toyoda
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Patent number: 6671468Abstract: A light source with a broadband frequency-periodic output spectrum for digital spectrally coded data, whereby the light source consists of a solid state laser that is frequency-modulated or phase-modulated within one bit period.Type: GrantFiled: May 19, 1999Date of Patent: December 30, 2003Assignee: AlcatelInventor: Thomas Pfeiffer
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Patent number: 6624917Abstract: Optical power adjustment is provided for parallel optical transmitters, in particular, for an array of vertical cavity surface emitting lasers (VCSEL's). The lasers in the array can be independently digitally adjusted with associated digital circuitry to compensate for manufacturing and temperature variations. In particular, the threshold current and modulation current for each VCSEL in the array, as well as a global temperature coefficient for all the VCSEL's in the array, can be digitally setup and adjusted for desired power levels. Once set, the associated digital code can be stored in non-volatile memory, and loaded at powering-up of the transmitters.Type: GrantFiled: October 28, 1999Date of Patent: September 23, 2003Assignee: International Business Machines CorporationInventors: Matthew James Paschal, Kevin Paul Demsky, Ladd William Freitag
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Patent number: 6594291Abstract: An etalon as a wavelength selection element is configured by an optical element whose transmittance or reflectivity cyclically varies, such that, of two oscillation lines of different wavelengths and light intensities in fluorine laser, when a center wavelength of an oscillation line having a stronger light intensity is situated at one selected wavelength in the element, a center wavelength of an oscillation line having a weaker light intensity is situated between two adjacent selected wavelengths in the element. Accordingly, it is possible to oscillate an ultra narrow band fluorine laser apparatus by one line only, a wavelength width of this line can be narrowed to about 0.2 pm, and the drop in laser output can be reduced. By monitoring the laser output (output characteristics) with the etalon serving as the wavelength selection element, the wavelength selected by the etalon can be adjusted so as to maximize the output of the laser output from the etalon.Type: GrantFiled: June 8, 2000Date of Patent: July 15, 2003Assignee: Komatsu Ltd.Inventor: Kiwamu Takehisa
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Patent number: 6577655Abstract: The invention pertains to a control circuit (4) for a radiation source (2). The circuit comprises means (43) for generating an error signal (Perr) which is indicative for a difference between a measured average value of the output power of the radiation source (2) and a desired average value (Pset) of the output power of the radiation source. The circuit further comprises combining means (44, 45, 46) for generating a control signal (Sout) for the radiation source (2) in response to said error signal (Perr) and to an information signal (Sin) for modulating the radiation source. The combining means comprise first means (44) for modifying the information signal by a multiplicative factor &ggr; which is dependent on the error signal, and second means (45, 46) for modifying the information signal by an additive factor &sgr; which is dependent on the error signal.Type: GrantFiled: February 7, 2001Date of Patent: June 10, 2003Assignee: Koninklijke Philips Electronics N.V.Inventor: James Joseph Anthony McCormack
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Publication number: 20030086451Abstract: The present invention provides a method and apparatus for controlling laser power, using at least two Brewster windows which are aligned along an axis which is parallel to the direction of the laser beam and which are rotatable around said axis, wherein the first Brewster window is rotated in one direction and the second Brewster window is rotated in the opposite direction. Preferably, both Brewster windows only have to rotate each through +/−45° to control transmission of the laser beam from maximum to minimum.Type: ApplicationFiled: July 22, 2002Publication date: May 8, 2003Inventors: Stephen Hastings, Peter Dullin, Alistair Gill, Erwin Wagner, Peter Von Jan, Wolfgang Hauck
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Patent number: 6556601Abstract: A variation in optical output of a semiconductor luminous device outputting an optical signal to an optical fiber which is caused due to a variation in ambient temperature and an end of a life thereof capable of being compensated for without measuring the optical output. An output variation quantity H0(Ta) of the semiconductor luminous device due to the ambient temperature Ta is operated in a step S2. In a step S4, an output reduction quantity ST of the semiconductor luminous device obtaining by accumulating an output reduction ST thereof per unit time due to a deterioration of the device is provided. In a step S5, it is judged that a life of the device reaches an end when the output reduction ST exceeds a reference value ST0. When the former fails to exceed the latter, a variation quantity IH(Ta) of a drive current command value due to the ambient temperature Ta and a current reduction quantity IST(ST, dST) determined due to a deterioration of the device are operated in a step S6.Type: GrantFiled: June 29, 2001Date of Patent: April 29, 2003Assignee: Sanyo Denki Co., Ltd.Inventor: Shin Nagata
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Patent number: 6539037Abstract: A laser apparatus has a function to easily select a component having a wavelength near to an oscillated wavelength of a laser beam from among components of a reference beam having a spectral distribution, which is already known, as a reference in measurement of the oscillated wavelength of the laser beam. The laser apparatus has a laser oscillator for outputting a laser beam, a reference light source for outputting a reference beam having a spectral distribution which is already known, two spectrum separation units having different resolving power, a detecting device for detecting a part of the laser beam and a part of the reference beam separated by the two spectrum separation units, and a control unit for measuring an oscillated wavelength of the detected laser beam by using as a reference a component selected from among components of the detected reference beam and having a wavelength near to the oscillated wavelength of the detected laser beam.Type: GrantFiled: August 1, 2000Date of Patent: March 25, 2003Assignee: Komatsu Ltd.Inventors: Koji Shio, Osamu Wakabayashi, Toru Suzuki
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Patent number: 6532244Abstract: An illumination system includes a multimode diode-laser and two optical fibers. Light from the diode-laser is directed into the first optical fiber having a first core diameter. The light exits the first optical fiber and is directed by an optical system into a second optical fiber having a core diameter greater than the first optical fiber and a numerical aperture greater than the numerical aperture of the optical system. A light beam exiting the second optical fiber has an intensity distribution having sharp edges and uniformity better than plus or minus ten percent over a central ninety percent of the beam.Type: GrantFiled: July 13, 2000Date of Patent: March 11, 2003Assignee: Lumenis Inc.Inventors: David A. Dewey, Lukas Hunziker