Abstract: A control system includes a field-programmable gate array (FPGA), a digital-to-analog conversion (DAC) circuit, an external TEC driver, and a pump chip. The field-programmable gate array (FPGA) includes a pump driver and a thermoelectric-cooler (TEC) controller. The digital-to-analog conversion (DAC) circuit is coupled to the FPGA. The external TEC driver is external to the FPGA and coupled to the FPGA. The pump chip includes a pump and a TEC and is coupled to the DAC circuit and the external TEC driver.

Abstract: A laser assembly is provided that includes a laser resonator that emits a first light having a first pulse width, and a trigger assembly electrically coupled to the laser resonator to actuate the laser resonator. The laser assembly also includes a sensor configured to detect the first light as the light emits from the laser resonator, and one or more processors coupled to the trigger assembly. The one or more processors are configured to obtain a first time delay interval from when the trigger assembly is actuated to when the sensor detects the first light, and actuate the laser resonator to emit a second light having a second pulse width based on the time delay interval determined.

Abstract: Described herein are methods for developing and maintaining pulses that are produced from compact resonant cavities using one or more Q-switches and maintaining the output parameters of these pulses created during repetitive pulsed operation. The deterministic control of the evolution of a Q-switched laser pulse is complicated due to dynamic laser cavity feedback effects and unpredictable environmental inputs. Laser pulse shape control in a compact laser cavity (e.g., length/speed of light <˜1 ns) is especially difficult because closed loop control becomes impossible due to causality. Because various issues cause laser output of these compact resonator cavities to drift over time, described herein are further methods for automatically maintaining those output parameters.

Abstract: A driver circuit for laser diodes is provided with first and second terminals for the laser diodes. The driver circuit also includes capacitors, each being assigned to a laser diode, and at least one input for connection to a charging means. Further included is at least one input for a control signal and at least one first switch means. Each capacitor is connected to the input for connection to the charging means, and a first terminal of each capacitor is connected to the first terminal for the laser diode. The second terminal for the laser diode is connected to a first terminal of the at least one first switch means, and a second terminal of each capacitor is connected to ground. A second terminal of the at least one first switch means is connected to ground and wherein the at least one input for a control signal is connected to a control terminal of the at least one first switch means.

Abstract: A laser assembly is provided that includes a laser resonator that emits a first light having a first pulse width, and a trigger assembly electrically coupled to the laser resonator to actuate the laser resonator. The laser assembly also includes a sensor configured to detect the first light as the light emits from the laser resonator, and one or more processors coupled to the trigger assembly. The one or more processors are configured to obtain a first time delay interval from when the trigger assembly is actuated to when the sensor detects the first light, and actuate the laser resonator to emit a second light having a second pulse width based on the time delay interval determined.

Abstract: Negative pressure wound therapy apparatuses and dressings, and systems and methods for operating such apparatuses for use with dressings are disclosed. In some embodiments, controlling the delivery of therapy can be based on monitoring and detecting various operating conditions. An apparatus can have a controller configured to monitor a duty cycle of a source of negative pressure. Based on the monitored duty cycle, the controller can determine whether a leak is present and provide an indication to a user. The controller can determine a duty cycle threshold in order to achieve an optimal or near optimal balance between an uninterrupted delivery of therapy, avoidance inconveniencing a user, conserving power, achieving optimal or near optimal efficiency, and/or limiting vibrational noise. In some embodiments, the duty cycle threshold is determined based at least in part on a capacity of a power source and an operational time of the apparatus.

Abstract: This disclosure is directed to, among other things, techniques to quickly replenish a capacitance of a laser diode driver circuit after an optical pulse, which can enable a burst of pulses (more than one pulse), such as to enable pulse coding. An energy reservoir circuit can be coupled to a laser diode driver circuit and to a power supply circuit and configured to store enough energy to fire the RD laser diode driver more than once. The energy reservoir circuit can act as an intermediate interface between the RD laser diode driver and the power supply circuit to better optimize the current requirements of each block.

Abstract: A driver circuit includes a fly capacitor with a first end and a second end. The driver circuit includes a laser diode having an anode and a cathode. The driver circuit is configured to operate in first and second operating states. The anode is coupled to the first end of the fly capacitor. In the first operating state, the cathode is coupled to a first voltage supply node, the first end of the fly capacitor is coupled to a second voltage supply node, and the second end of the fly capacitor is coupled to a first reference terminal. In the second operating state, the cathode is coupled to a second reference terminal and decoupled from the first voltage supply node, the first end of the fly capacitor is decoupled from the second voltage supply node, and the second end of the fly capacitor is coupled to a third reference terminal.

Abstract: In certain embodiments, a system for detecting a peak laser pulse includes a laser, a photodiode configured to detect pulses emitted by the laser, and circuitry for detecting a peak pulse timing of the laser. The circuitry is configured to receive a periodic series of voltage signals based on laser pulses detected by the photodiode, stretch the voltage signals, and obtain sampled voltages from the stretched voltage signals using periodic control signals. The circuitry is further configured to shift the timing of the periodic control signals, compare the sampled voltages for respective timings of the control signals, and select an optimal control signal timing based on the comparison.

Abstract: An impedance matching circuit for a gas-laser excitation system includes a high-frequency connection line configured to be connected at a first connection point to a power source and at a second connection point to a gas-laser electrode. The impedance matching circuit is characterized in that an impedance of at least one section of the high-frequency connection line changes by a change to a configuration of the high-frequency connection line, in particular to at least one parameter of the high-frequency connection line in the at least one section.

Abstract: A laser source for use in providing a laser beam for industrial operations in an industrial plant. The laser source selectively providing a first laser beam at a first outlet having relatively high power and lower beam quality and a second laser beam at a second outlet having relatively lower power and higher beam quality. The laser source including an optical path selector device for selectively transmitting a first laser beam along a first or second optical line toward respective first and second outlets. The second optical path having an optical amplification unit for changing the first laser to the second laser. An industrial plant including at least a first laser source selectively controls the first laser source to provide the first and the second lasers to predetermined laser processing stations. A second laser source may be used and controlled to provide a first or second laser to an alternate laser processing station on a failure of another laser source.

Abstract: A method for preventing spatial or spectral beam seeding in a Q-switched laser is described. The Q-switch trigger of the laser is delayed by several laser resonator lifetimes after the end of the pump pulse. In this way, beam seeding is completely eliminated whilst pre-lase is maintained. The method described may be used for any laser system where the fall time of the pump radiation is sufficiently fast with respect to the upper state lifetime of the laser medium.

Abstract: A light emitting device which includes at least one of a laser light source (1), wiring (9), a lens for excitation (2), a luminous body (4), a laser cut filter (6), a half parabolic mirror (5P), and a base (5h), in which a part of the wiring (9) is installed at a portion in which a breakage easily occurs due to at least one deformation of the laser light source (1), the lens for excitation (2), the luminous body (4), the laser cut filter (6), the half parabolic mirror (5P), and the base (5h), or a change in an installation position thereof.

Abstract: A microlaser system includes an optical source, a microlaser, an actuator switch, and a photovoltaic power source. The microlaser, which includes a control element, is optically pumped by at least a portion of light emitted by the optical source. The actuator switch is configured to be activated by a triggering event. Furthermore, the photovoltaic power source is coupled in a series connection with the actuator switch and the control element, the series connection configured to connect the photovoltaic power source to the control element of the microlaser when the actuator switch is activated by the triggering event.

Abstract: A laser driver circuit having a differential circuit and an output circuit includes a control circuit receiving a regulated supply voltage that also supplies the differential circuit as an input signal. The control circuit generates a feedback voltage across a first resistor to cause a first current to flow in the first resistor having a current value equal or proportional to the modulation current value. The laser driver circuit includes an operational amplifier receiving the feedback voltage and a reference voltage indicative of a desired modulation current value and to generate the regulated supply voltage. The control circuit and the operational amplifier form a feedback control loop to adjust the regulated supply voltage to regulate the feedback voltage to be equal to the reference voltage, thereby regulating the modulation current value to the desired modulation current value.

Abstract: An assembly that includes a laser diode and a driver circuit that operates to give the assembly an adjustable impedance. The driver circuit adjusts impedance by repeatedly alternating between two operational phases. In one operational phase, current is primarily or fully supplied through the laser diode using a first current path being from the first supply node, to the laser diode, and into the second supply node. In the other operational phase, current is supplied through the laser diode using a recirculating second current path. The current through the laser diode increases during the first operational phase, and decays during the second operational phase. For a given applied voltage level between the first and second supply nodes, the duty cycle of the first and second operational phases may be adjusted so that the current through the laser diode is approximately a target current.

Abstract: A good way to avoid extreme current levels when supplying large amounts of power is to increase the voltage. The easiest way to do this is connecting the radiation elements (e.g. laser diode pixels) in series (La1 to La-n). In such a pixelated driver, the amount of components and complexity per pixel are reduced by connecting as many radiation elements as possible in series, supplying the string by one current controlled driver (Is), shortening pixels which should be in off state by a switch in parallel (40-1 to 40-n) to the radiation element, storing binary on/off information (30-1 to 30-n) for each pixel locally, creating a floating supply (20-1 to 20-n) for the switches, and managing information transfer to the floating storage and switches.

Abstract: A laser light source module includes a laser source, a connecting unit, a controlled switch unit, and a verification unit. When a verification signal is received, the verification unit judges whether the verification signal complies with a verifying condition. If the verification signal complies with the verifying condition, the controlled switch unit is in the on state, so that a first output voltage is transmitted to the laser source through the controlled switch unit to drive illumination of the laser source. Whereas, if the verification signal does not comply with the verifying condition, the controlled switch unit is in the off state, so that the first output voltage fails to be transmitted to the laser source through the controlled switch unit and the laser source is turned off.

Abstract: An apparatus operates at least one light-emitting diode in the form of a laser diode. The light-emitting diode is interconnected in series with the load section of a controllable semiconductor element and a current measuring resistor between a first supply voltage terminal and a second supply voltage terminal. The supply voltage terminals are the output connections of a voltage-regulating circuit in the form of a DC voltage boost converter which provides a supply voltage), and wherein a current-regulating circuit is provided for the current through the at least one light-emitting diode, whose actuator is the controllable semiconductor element.

Abstract: A method and a device include a fiber laser generating a laser pulse for processing materials. An optical switching element disposed in a beam path of a laser beam is closed at the earliest when an output power of the laser beam falls below a specified value.

Abstract: A light determination circuit having a laser module and a detection circuit is provided. The detection circuit comprises a threshold voltage determination unit, a comparison unit and a switch unit. The threshold voltage determination unit determines a threshold voltage corresponding to the laser module. The comparison unit is for comparing a voltage level at a first node of the laser module with the threshold voltage to output a switch signal. The switch unit is controlled by the switch signal to switch the voltage level at an output end of the detection circuit. When the laser module is conducted, the voltage level at the first node is lower than the threshold voltage, the switch signal controls the switch unit, such that the output end outputs a high level voltage and vice versa.

Abstract: In one embodiment, a driver circuit of a vertical-cavity surface-emitting laser (VCSEL) includes bias current sources, modulation current sources, and a switch component connected to the bias current sources at a first node and to the modulation current sources at second nodes; the switch component is configured to modulate a current from the bias and modulation current sources based on an input signal to the switch component; and the switch component is also configured to provide the modulated current to the VCSEL through a folded cascode transistor.

Abstract: Apparatus and systems create differential drive signals suitable for HAMR data recording. A laser diode differential driver provides heating current pulses at a time ?1. The pulses energize a laser diode to pre-heat the magnetic medium to be written. Some embodiments duplicate portions of the laser diode circuit architecture to create a magnetic write head differential driver. The write head driver provides write current pulses to a magnetic write head in one direction with ?1 timing and in the opposite direction with ?2 timing. Both drivers utilize sets of reference voltages capable of being switched to one terminal or the other of the element to be driven. In the laser diode case, the common mode is split between the anode and cathode sections of the driver. A feedback element is added between the cathode and anode sections to provide current accuracy independent of the electrical characteristics of the selected laser diode.

Abstract: Circuit arrangement or circuit, in particular driver circuit, and a method for controlling at least one light-emitting component, such as an electro-optical transducer, a light-emitting diode (LED), an electroluminescent diode, a laser, or a semiconductor laser, by switching a switching element between a first switching position and a second switching position, and the voltage supply is effected by a supply element, such as a voltage source or a current source supported by a decoupling capacitor on the output side, so that current drain and output resistance are as low as possible, so that the highest possible frequency or switching speed as well as the highest possible output voltage for the light-emitting component can be achieved, the light-emitting component is controlled by varying its operating voltage, in particular by switching between the switching positions, and the first and second switching positions are of low impedance for the operating frequency.

Abstract: An opto-electronic oscillator circuit, including: an opto-electronic circuit loop including an optical modulator that receives a first electrical signal and produces an optical output signal coupled with an optical resonator, a photodetector circuit optically coupled with the optical resonator, and a phase shifter coupled with the photodetector circuit for producing a phase shifted output signal that is fed back as the first electrical signal; an optical loop comprising the optical coupling of the optical resonator with the photodetector; and an electrical feedback circuit loop for coupling the first electrical signal with the photodetector circuit.

Abstract: An electro-optical distance measuring device includes a laser driver for a laser diode for emitting laser light pulses. The measuring device further includes a laser diode voltage supply having a cascade of at least two voltage regulators, each of which provides an output voltage at a level below a laser threshold voltage of the laser diode. By changing from a first to a second switching position of an electronic switching element of the measuring device, one of the laser light pulses can be emitted and, in the steady-state first and the steady-state second switching positions, no laser light is emitted.

Abstract: Embodiments of the present disclosure provide laser safety techniques and configurations. In one embodiment, an optical module includes a first die including a laser configured to transmit optical signals, a first node electrically coupled with the laser, and a second node electrically coupled with the laser, and a second die including a power supply line configured to provide power to the laser, a third node electrically coupled with the power supply line and electrically coupled with the first node to provide the power to the laser, a fourth node electrically coupled with the second node of the first die, and a switch configured to prevent the power of the power supply line from reaching the laser through the third node based on a voltage of the fourth node when a laser fault event occurs. Other embodiments may be described and/or claimed.

Abstract: Proposed is a light emitting module (1), comprising a semiconductor light emitting device (10) and a thermal switch (20). The thermal switch (20) is arranged to protect the device (10) from over heating. At elevated temperatures the junction of the device (10) may reach a critical level causing catastrophic breakdown of the device. According to the invention, the thermal switch is arranged to shunt the semiconductor light emitting device. This is especially advantageous as the thermal protection offered by the switch (20) correlates directly to the (junction) temperature of the device (10).

Abstract: A driver circuit is provided which comprises a series-connected unit having a light-emitting element and a current limiting inductor directly connected to the light-emitting element, a regenerative diode which is connected in parallel to the series-connected unit and which regenerates energy stored in the current limiting inductor, a transistor which controls a current flowing through the light-emitting element and the current limiting inductor, and a controller which controls an operation of the transistor, wherein the controller controls the transistor according to a voltage value of a power supply applied to the light-emitting element.

Abstract: A laser light source module includes a laser source, a connecting unit, a controlled switch unit, and a verification unit. When a verification signal is received, the verification unit judges whether the verification signal complies with a verifying condition. If the verification signal complies with the verifying condition, the controlled switch unit is in the on state, so that a first output voltage is transmitted to the laser source through the controlled switch unit to drive illumination of the laser source. Whereas, if the verification signal does not comply with the verifying condition, the controlled switch unit is in the off state, so that the first output voltage fails to be transmitted to the laser source through the controlled switch unit and the laser source is turned off.

Abstract: A semiconductor laser driving device and an image forming apparatus are disclosed that are capable of accurately detecting the deterioration of the semiconductor laser with a smaller circuit size and regardless of the variation of the characteristics of the semiconductor laser and the use conditions of the semiconductor laser by adding a minimum circuit are disclosed. In the semiconductor laser driving device, the output voltage generated by an operational amplifier circuit by amplifying a voltage difference between a monitoring voltage (Vm) and a predetermined reference voltage (Vref) is transmitted to a bias current generating circuit unit as a bias current setting voltage (Vbi) through a sample/hold circuit having a switch (SW1) and a sample/hold capacitor (Csh). When the bias current setting voltage (Vbi) is greater than a predetermined voltage, a deterioration detecting circuit transmits a deterioration detecting signal indicating that the deterioration of the semiconductor laser is detected.

Abstract: An apparatus is provided. The apparatus includes a lasing element, a laser driver and logic. The laser driver is configured to drive the lasing element at multiple current levels, and the laser driver includes a switching network, multiple direct current (DC) loops, and an output circuit. The switching network receives a differential input signal, and each DC loop is coupled to the switching network. The output circuit is also coupled to the lasing element, and the logic is coupled to each of the DC current loops, where the logic selects one or more of the DC loops in each (of several) modes. Each mode generates one or more output lasing currents for the lasing element that corresponds to a one or more of the current levels in response to the differential input signal.

Abstract: An optical-pickup apparatus includes: a first laser light source including a first laser diode to emit a laser beam having a first wavelength, and a back-monitor photodetector to receive the laser beam emitted in a backward direction, not being an optical-disc direction, and output a first monitor signal; a second laser-light source including a second laser diode to emit a laser beam having a second wavelength; a light-receiving circuit including a front-monitor photodetector to receive the laser beam emitted in a forward direction, being the optical-disc direction, and output a second monitor signal, and a switch circuit to be inputted with the first and second monitor signals, and output the first or second monitor signal according to a switch signal; and first and second drive circuits to drive the first and second laser diodes according to the first and second monitor signals outputted from the light-receiving circuit, respectively.

Abstract: A disclosed laser diode driving device drives laser diodes with driving currents obtained by adding switch currents to corresponding bias currents and includes a common switch current generating circuit configured to generate a common switch current according to an input signal; switch current generating circuits provided for the corresponding laser diodes and configured to generate the switch currents based on the common switch current and input signals; switches configured to control the output of the switch currents to the corresponding laser diodes according to input signals; bias current generating circuits configured to generate the bias currents and output the generated bias currents to the corresponding laser diodes; and a control unit configured to detect the light intensities of the respective laser diodes and to control the common switch current generating circuit, the switch current generating circuits, and the switches to adjust the light intensities of the respective laser diodes.

Abstract: A Dynamically Variable Spot Size (DVSS) laser system for bonding metal components includes an elongated housing containing a light entry aperture coupled to a laser beam transmission cable and a light exit aperture. A plurality of lenses contained within the housing focus a laser beam from the light entry aperture through the light exit aperture. The lenses may be dynamically adjusted to vary the spot size of the laser. A plurality of interoperable safety devices, including a manually depressible interlock switch, an internal proximity sensor, a remotely operated potentiometer, a remotely activated toggle and a power supply interlock, prevent activation of the laser and DVSS laser system if each safety device does not provide a closed circuit. The remotely operated potentiometer also provides continuous variability in laser energy output.

Abstract: The present invention comprises, in various embodiments, systems and methods for shutting down a laser system in an intelligent and flexible manner. An intelligent laser interlock system includes both hardwired components, and intelligent components configured to execute computing instructions. The hardwired components and the intelligent components are configured to shutdown the laser system to one or more alternative shutdown states in response to one or more interlock signals.

Abstract: A method and apparatus are disclosed for controlling bandwidth in a multi-portion laser system comprising a first line narrowed oscillator laser system portion providing a line narrowed seed pulse to an amplifier laser system portion, may comprise utilizing a timing difference curve defining a relationship between a first laser system operating parameter other than bandwidth and the timing difference and also a desired point on the curve defining a desired timing difference, wherein each unique operating point on the curve corresponds to a respective bandwidth value; determining an actual offset from the timing difference at the desired point on the curve to an actual operating point on the curve; determining an error between the actual offset and a desired offset corresponding to a desired bandwidth; modifying the firing differential timing to remove the error between the actual offset and the desired offset.

Abstract: Many approaches to tunable lasers use an array of DFBs, where each element of the array has a different wavelength. In some operations one element of the array is activated at a time depending on the desired wavelength. For modulated applications, an RF voltage is applied to a specific element of the DFB array, generally using an RF switch. In standard configurations, the demands on the switch are relatively difficult, generally requiring low RF insertion loss and good high frequency performance to 10 GHz. The DFB arrays are generally common cathode or common anode, depending on the type of the substrate used to fabricate the devices. Described herein is an array with a common cathode or anode configuration using a MEMS based switch that shorts the selected laser to RF ground. With this topology, preferably the off-state capacitance should be low with the MEMS switch.

Abstract: Disclosed herein is a laser driver including a light emission controlling section configured to stop generation of a control voltage by a control voltage generating section, causing a given voltage corresponding to a magnitude of a reference current to be outputted to an input node of a first emitter follower to operate the first emitter follower for a first time period from start of a light emission time period, release stop of the generation of the control voltage by the control voltage generating section, causing the control voltage to be outputted to the input node of the first emitter follower to operate the first emitter follower until end of the light emission time period of the laser, and operate a second emitter follower to discharge electric charges accumulated in the laser for a second time period after the end of the light emission time period of the laser.

Abstract: A system for self-aligning assembly and packaging of semiconductor lasers allows reduction of time, cost and testing expenses for high power density systems. A laser package mounting system, such as a modified TO-can (transistor outline can), has modifications that increase heat transfer from the active laser to a heat exchanger or other heat sink. A prefabricated heat exchanger assembly mounts both a laser package and one or more lenses. Direct mounting of a fan assembly to the package further minimizes assembly steps. Components may be physically and optically aligned during assembly by clocking and other indexing means, so that the entire system is self-aligned and focused by the assembly process without requiring post-assembly adjustment. This system can lower costs and thereby enable the use of high powered semiconductor lasers in low cost, high volume production, such as consumer items.

Abstract: A compact mid-IR laser device utilizes a quantum cascade laser to provide mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. The compact housing size may be approximately 20 cm×20 cm×20 cm or less. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser is thermally coupled. The heat spreader not only serves to dissipate heat and conduct same to the TEC, but also serves as an optical platform to secure the optical elements within the housing in a fixed relationship relative on one another.

Abstract: A laser drive circuit and use of digital-to-analog converters is provided, each with a current input and a current output to set current values of partial currents switchable by means of digital channel signals to provide a laser current pulse at least on the basis of a sum of partial currents, wherein at least one current output of one of the digital-to-analog converters is connected to at least one current input of an additional digital-to-analog converter via an analog switch.

Abstract: An on-the-fly analog switching method and system for providing a switching time of less than one second between energy levels and laser heads for laser shock peening applications. An analog switch is used with variable resistance devices that produce a switching time of less than one second. One advantage of the present invention is that a switching time of less than one second is provided which provides for an energy and time efficient system. The laser shock peening process is never delayed for switching purposes as the switching occurs during the standard pause between treated linear areas.

Abstract: In a semiconductor device, a switching current generator circuit generates and outputs a switching current such that a voltage input to a switching current setting terminal is equal to a voltage input to a switching current control terminal, and a bias current generator circuit generates and outputs a bias current such that a voltage input to a bias current setting terminal equals a voltage input to a bias current control terminal. A memory circuit inputs a voltage according to an amount of light emitted by a semiconductor laser, and generates a voltage to make the input voltage equal to a predetermined first reference voltage corresponding to a predetermined amount of light. An APC output terminal outputs the voltage output by the memory circuit to an external device. A current adding circuit combines the switching current and the bias current to generate a drive current to drive the semiconductor device.

Abstract: A method and apparatus are disclosed for controlling bandwidth in a multi-portion laser system comprising a first line narrowed oscillator laser system portion providing a line narrowed seed pulse to an amplifier laser system portion, may comprise utilizing a timing difference curve defining a relationship between a first laser system operating parameter other than bandwidth and the timing difference and also a desired point on the curve defining a desired timing difference, wherein each unique operating point on the curve corresponds to a respective bandwidth value; determining an actual offset from the timing difference at the desired point on the curve to an actual operating point on the curve; determining an error between the actual offset and a desired offset corresponding to a desired bandwidth; modifying the firing differential timing to remove the error between the actual offset and the desired offset.

Abstract: A laser (10) provided with a discharge activation power supply (11) supplied with power from a 3-phase AC power line, the discharge activation power supply (11) provided inside it with three first capacitors (12a, 12b, and 12c), the laser (10) including an external ground fault protection device comprising a voltage measuring unit using the first capacitors (12a, 12b, and 12c) to measure voltages between the phases of the 3-phase AC power line and the ground and a power breaking unit (18) comparing the values of voltages measured by the voltage measuring unit and a predetermined threshold and breaking the supply of power from the 3-phase AC power line to the power supply (11) when the value of a voltage exceeds the threshold.

Abstract: Proposed is a light emitting module (1), comprising a semiconductor light emitting device (10) and a thermal switch (20). The thermal switch (20) is arranged to protect the device (10) from over heating. At elevated temperatures the junction of the device (10) may reach a critical level causing catastrophic breakdown of the device. According to the invention, the thermal switch is arranged to shunt the semiconductor light emitting device. This is especially advantageous as the thermal protection offered by the switch (20) correlates directly to the (junction) temperature of the device (10).

Abstract: A light source device includes a plurality of first laser emission units and a plurality of second laser emission units for emitting light. The plurality of first laser emission units and the plurality of second laser emission units are disposed on a flat surface. The first laser emission units and the second laser emission units are composed so that a drive for light emission is sequentially switched. Each of the second laser emission units is disposed between the adjoining first laser emission units.

Abstract: A laser diode module with an adjustable monitoring current, wherein the photo diodes monitoring the light-emitting power of the laser diode are arranged in array, and wherein a programmed photo diode is formed by the photo diodes in match of a memory and switch control unit. In this way, the problem of an inconstant monitoring current of the prior art is avoided. Meanwhile, an adjustable monitoring current is achieved.

Abstract: Pickup head circuits with a protection circuit capable of preventing unexpected large current flowing through a laser diode during power-on interval. A driving transistor is coupled between a laser diode and a first power voltage, an automatic laser power control (ALPC) circuit is coupled between the first power voltage and a second power voltage, controlling the driving transistor to drive the laser diode. A protection circuit is coupled between the power voltage and a control terminal of the driving transistor, forcing a voltage at the control terminal of the driving transistor to follow the first power voltage during a power-on interval.