A laser system comprising high voltage AC-to-DC power converter and one or more current sources coupled to the high voltage AC-to-DC power converter without a DC-to-DC converter between the one or more current sources and the AC-to-DC power source. Each of the one or more current sources includes a high voltage switch and one or more independent safety shutoffs. A laser module is operably coupled to the one or more current source and configured to emit electromagnetic radiation wherein the one or more safety shutoffs are configured to disable emission of electromagnetic radiation from the laser module when triggered.

The present disclosure provides an automatic power control circuit and method, and a laser diode circuit comprising the automatic power control circuit. The automatic power control circuit comprises: a voltage measurement unit configured to obtain an indicative voltage at a specific measurement point and output the indicative voltage to a processor, wherein the indicative voltage is configured to indicate a forward voltage of a laser diode in laser emitting state; and the processor configured to output a pulse parameter control signal in response to change in the indicative voltage, wherein the pulse parameter control signal is used to control an adjustment for a pulse parameter of laser pulses of the laser diode, such that laser emission power is within a preset range, and wherein the pulse parameter of the laser pulses of the laser diode is used to set a total duration of pulses within a preset time period.

The present invention provides methods and an apparatus for monitoring the optical output power of a laser diode (LD) having an associated photodiode (PD), and a particle sensor apparatus. The photodiode (PD) is operable together with the laser diode (LD), wherein it detects the light (LS) of the laser diode (LD) and converts it into an electrical current, and is thermally coupled to the laser diode (LD). Monitoring of the optical output power P is effected during the operation of the laser diode (LD) and is based on current measurements and/or voltage measurements at the laser diode (LD) and at the photodiode (PD).

A laser system includes a high voltage AC-to-DC power converter and one or more current sources coupled to the power converter without a DC-to-DC converter between the current sources and the power converter. Each of the current sources includes a high voltage switch and one or more independent safety shutoffs. A laser module is operably coupled to the one or more current source and configured to emit electromagnetic radiation wherein the one or more safety shutoffs are configured to disable emission of electromagnetic radiation from the laser module when triggered. A current source controller coupled to the safety shutoff(s) is configured to generate enabling signals that enable normal current source operation. The controller includes circuitry configured to measure power across the high voltage switch when the controller instructs the high voltage switch to turn off to determine proper operation of the safety shutoff(s).

A current control device supplies a current to a semiconductor laser in order to output laser light to the semiconductor laser, and includes a current commander and a supplier. The current commander outputs a command value corresponding to a current value by increasing the command value with a lapse of time until reaching a target command value corresponding to a current value for outputting the laser light with a predetermined strength. The supplier supplies a current with a size corresponding to the command value output by the current commander to the semiconductor laser.

The light source control apparatus controls drive of multiple light sources included in a light source unit to be used in a state where the multiple light sources are lit. The multiple light sources each include multiple light-emitting elements. The light source control apparatus includes an acquirer acquiring temporal information relating to a temporal change of each of the light sources, an estimator acquiring an estimated lifetime of each of the multiple light sources by using the temporal information, and a controller decreasing, when the multiple light sources include a first light source whose estimated lifetime is shorter than a target lifetime set for the light source unit, a light emission amount of the first light source.

A pulsed laser diode array driver includes an inductor having a first terminal configured to receive a source voltage, a source capacitor coupled between the first terminal of the inductor and ground, a bypass capacitor connected between a second terminal of the inductor and ground, a bypass switch connected between the second terminal of the inductor and ground, a laser diode array with one or more rows of laser diodes, and one or more laser diode switches, each being connected between a respective row node of the laser diode array and ground. The laser diode switches and the bypass switch are configured to control a current flow through the inductor to produce respective high-current pulses through each row of the laser diode array, each of the high-current pulses corresponding to a peak current of a resonant waveform developed at that row of the laser diode array.

The present disclosure relates generally to a device, such as a wearable display device configured with a laser diode driver implementing dynamic voltage control for laser diodes. The laser diodes may include one or more of a red laser diode, a blue laser diode, and a green laser diode. The device may determine a load condition based on a frame to be displayed at the device, and determine a target voltage level for a laser diode operably coupled to the laser diode driver of the device based on the load condition (e.g., an image signal processor (ISP) frame buffer load). The device may generate the target voltage level for the laser diode based on a base voltage level. For example, the device may be configured with a voltage booster operably coupled to the laser diode driver to provide the target voltage level in addition to the base voltage level.

A drive apparatus includes a light emitting device, a light receiving device configured to receive light emitted by the light emitting device, a comparison circuit configured to compare a light quantity of light detected by the light receiving device with a target value indicating a light quantity of light to be emitted by the light emitting device and generate a control signal corresponding to a comparison result, and a drive circuit configured to supply a drive signal corresponding to the control signal to the light emitting device. The drive circuit includes a gain changing switch configured to change, in accordance with the target value, a gain of the drive circuit.

A light emitter includes a substrate, a first semiconductor layer having a first conductivity type, a second semiconductor layer having a second conductivity type different from the first conductivity type, a light emitting layer provided between the first semiconductor layer and the second semiconductor layer and capable of emitting light when current is injected into the light emitting layer, and a third semiconductor layer provided between the substrate and the first semiconductor layer and having the second conductivity type, in which the first semiconductor layer is provided between the third semiconductor layer and the light emitting layer, and the third semiconductor layer has a protruding/recessed structure.