Abstract: A laser pulse emitter circuit comprises a laser diode and a laser diode driver circuit. The laser diode driver circuit includes an inductive circuit element in series with the laser diode, at least one capacitive circuit element connected in series with the inductive circuit element, and a switch circuit configured to activate the laser diode using duty cycling that includes an on-period and an off-period, wherein energy used in an activation of the laser diode is stored in the inductive circuit element and the at least one capacitive circuit element, and the stored energy is recycled by use in a subsequent activation of the laser diode.

Abstract: A device for the protection of laser optics or to their lifetime increase. The device for the protection of laser optics comprises a housing arranged below a laser optics housing with a connection for the supply of a cutting gas, and on the opposite side to the laser optics outlet nozzle for the cutting gas and a pressure-resistant protective glass on the side of the laser optics and a process-side protective glass, which is arranged between the nozzle and pressure-resistant protective glass available.

Abstract: A control device that can apply a laser oscillator control device to various types of systems. The control device includes an analog signal input unit configured to receive an output control signal for controlling a laser output of the laser oscillator or a mode control signal for controlling an operation mode of the laser oscillator as an analog signal; a digital signal input unit configured to receive the output control signal or the mode control signal as a digital signal; and a controller configured to transmit a laser command for controlling the laser output to the laser oscillator in response to the output control signal received by the analog signal input unit or the digital signal input unit, and transmit an operation command for operating the laser oscillator to the laser oscillator in the operation mode in response to the mode control signal received by the analog signal input unit or the digital signal input unit.

Abstract: In some examples, an apparatus includes a multi-layer code generator to generate codewords based on application of a plurality of layers of encoding, an optical source to produce encoded optical pulses based on the generated codewords, and an optical coupler to propagate the encoded optical pulses to an optical medium.

Abstract: A programmable circuit includes an array of printed groups of microscopic transistors or diodes having pn junctions. The devices are pre-formed and printed as an ink and cured. The devices have a proper orientation and a reverse orientation after settling on a conductor layer. The devices are connected in parallel within small groups. To neutralize the reverse-oriented devices, a sufficient voltage is applied across the parallel-connected diodes to forward bias only the devices having the reverse orientation. This causes a sufficient current to flow through each of the reverse-orientated devices to destroy an electrical interface between an electrode of the devices and the conductor layer to create an open circuit, such that those devices do not affect a rectifying function of the devices in the group having the proper orientation. An interconnection conductor pattern may then interconnect the groups to form complex logic circuits.

Abstract: The excimer laser apparatus may include a laser chamber configured to contain gas, a pair of electrodes provided in the laser chamber, a power source unit configured to supply a pulse voltage between the pair of electrodes, a gas supply unit configured to supply gas into the laser chamber, a gas exhaust unit configured to partially exhaust gas from within the laser chamber, and a gas control unit configured to control the gas supply unit and the gas exhaust unit, where a replacement ratio of gas to be replaced from within the laser chamber increases as deterioration of the pair of electrodes progresses, the deterioration being represented by a deterioration parameter of the pair of electrodes.

Abstract: A laser apparatus may comprise: a laser chamber configured to include a laser gain medium; a pair of electrodes disposed in the laser chamber; an energy detector configured to measure pulse energy of laser beams outputted by discharging between the pair of the electrodes; an optical element disposed on a light path of the laser beams; and a controller configured to calculate an integration value of absorption energy at the optical element, and determine whether the integration value exceeds a lifetime integration value of the optical element based on the pulse energy of the laser beams.

Abstract: An addressable illuminator is disclosed consisting of multiple optical sources used in combination with an electrical circuit so that different combinations of the optical sources can be energized without exceeding eye-safety limits. Operation of multiple optical sources may be proximate, which is eye-safe, regardless of the number of or which ones of the optical sources are energized and regardless of the position of observers. An illuminator with multiple optical sources remains eye-safe when there are single-point electrical failures, such as short circuits, in the driving circuit. Monitoring or a feedback loop for the output power is not required or necessary to control the distance of an observer in order to be eye-safe.

Abstract: The specification and drawings present an apparatus and a method for protecting lasers or other sources of high optical power from damage due to external sources of contamination using a concept of a sacrificial optical component and automatic laser shutdown based on a pressure indication of a substantial damage to the sacrificial optical component such as puncturing through that component.

Abstract: A semiconductor laser device includes a semiconductor laser element having an active layer and semiconductor layers on opposite sides of the active layer, and a PN-junction diode in part of the semiconductor layers. The PN-junction diode is connected, in inverse polarity, in parallel with the semiconductor laser element.

Abstract: There provided is a semiconductor laser control device which including plural light sources that are configured with eight or more semiconductor laser elements, a one detecting section that detects a light power of the light sources, a light power control unit that compares a signal according to a light power detected by the detecting section with a control signal corresponding to a predetermined light power to control a current supplied to the light sources, and a voltage clamp circuit that functions as an overvoltage preventing means for the detecting section when turning on each of the light sources to perform light power control.

Abstract: Output power of a laser beam emitted by a laser in an electro-optical reader is regulated by storing a killswitch byte in non-volatile memory, and by checking whether the killswitch byte is in a default state or a kill state prior to performing reading. A controller detects a fault condition and responsively changes the killswitch byte to the kill state, in order to permanently deenergize the laser and to maintain the laser permanently deenergized after the killswitch byte has been changed to the kill state.

Abstract: The disclosure provides a quality detection device for laser source and the quality detection method thereof. The laser source quality detection device comprises: a reflective mirror set located in a range of emitting light from the laser source for receiving light beams from the laser source, and having at least one reflective mirror to reflect the light emitted from the laser source in a profile the same as that of the light emitted from the laser source; and at least one sensor capable of receiving the reflected light out of a predetermined range so as to determine quality of the laser source.

Abstract: A method and device for providing a laser interlock having a first optical source, a first beam splitter, a second optical source, a detector, an interlock control system, and a means for producing dangerous optical energy. The first beam splitter is optically connected to the first optical source, the first detector and the second optical source. The detector is connected to the interlock control system. The interlock control system is connected to the means for producing dangerous optical energy and configured to terminate its optical energy production upon the detection of optical energy at the detector from the second optical source below a predetermined detector threshold. The second optical source produces an optical energy in response to optical energy from the first optical source. The optical energy from the second optical source has a different wavelength, polarization, modulation or combination thereof from the optical energy of the first optical source.

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: The invention relates to the field of laser sources (3), and for specifically to inhibiting damage due to misuse of a laser source (3), in particular of a high-power laser source (3) provided in a consumer product (1). The proposed device (1) includes at least a laser source (3) and a safety unit (2), wherein by means of the arrangement of the safety unit (2) it is provided that potential harm caused by misuse of the laser source (3) based on an unauthorized access to the laser source (3) is confined or even prevented by reducing the power level of the output of the laser source (3) or by even completely stopping any laser output therefrom. A corresponding method of providing a laser source (3) and a further method of preventing misuse of a laser source (3) are also proposed.

Abstract: A semiconductor device includes a vertical cavity surface emitting laser (VCSEL) with an integrated protection diode arranged between the VCSEL and an emitting surface. By locating the protection diode above the VCSEL, a minimal increase in substrate area is consumed to protect the VCSEL from electrostatic discharge events. A relatively small capacitance introduced by the protection diode, is controllably adjusted by one of the radial size of the protection diode and the thickness of the intrinsic layer therein. The relatively small capacitance introduced by the protection diode enables the VCSEL to operate at data rates above 10 Gb/s.

Abstract: A fiber laser apparatus in which pump light is introduced into an optical fiber to generate laser light includes a detecting section that detects signal light leaking out from a core of the optical fiber as leakage signal light, a determining section that determines that, in a case where there is a decrease in an intensity of the leakage signal light detected in the detecting section, a failure of the fiber has occurred, and a stopping section that stops, in a case where the determining section has determined that a failure of the fiber has occurred, the introduction of the pump light into the optical fiber. The detecting section detects the leakage signal light leaking out of a High Reflectivity FBG that is provided on a side opposite to an output side of the laser light.

Abstract: A semiconductor laser driving device that drives a semiconductor laser with a driving current output from a driving current output terminal is disclosed. The semiconductor laser driving device includes a driving current monitoring terminal configured to output a driving current monitoring current having a value of 1/? of the driving current; a current-voltage conversion resistor connected to the driving current monitoring terminal and configured to convert the driving current monitoring current having the value of 1/? of the driving current into a corresponding driving current monitoring voltage; and a detector configured to generate a reference voltage and detect whether the corresponding driving current monitoring voltage has reached the reference voltage.

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: A safety and interlock circuit for use with devices which could cause injury if an error condition causes improper operation. A control program executing on a processor monitors a variety of device conditions, including pulse over-duration threshold, diode over-current threshold, pulse lock-out duration, temperature threshold, and pulse repetition frequency limit, and prevents the laser from firing if an error condition is detected. In addition, the error conditions are logged in a persistent memory to facilitate subsequent diagnosis and correction.

Abstract: A protection circuit for protecting light-emitting diodes of a laser emitter is provided. The laser emitter includes a first LED for reading multimedia data stored in a first media and a second LED for reading multimedia data stored in a second media. Cathodes of the first LED and the second LED are grounded, and anodes of the first LED and the second LED are connected with soldering tin. The protection circuit includes a first protection element with a first breakdown voltage and a second protection element with a second breakdown voltage. One end of each of the first protection element and the second protection element is grounded. When the circuit is connected to the laser emitter, residual ends of the first protection element and the second protection element are respectively connected to the anodes of the first LED and the second LED.

Abstract: A method of closed loop control for an optical link is presented, utilizing a copper feedback connection between the optical transmitter and optical receiver, suitable for short distance applications. An architecture is provides that may be used to define and maintain an optimum optical launch power for a defined bit error rate, guaranteeing extinction ratio and absolute optimum operating power. The invention also includes the use of such a loop in achieving fast link initialization and dynamic optimization to compensate for all effects of time and temperature for all components within the link.

Abstract: A scanning projector includes a MEMS device with a scanning mirror that sweeps a light beam in two dimensions. A laser limit comparison circuit determines a metric from measured peak scan angles and measured light output. The metric is compared to a threshold and a light source is shut down when the metric exceeds the threshold.

Abstract: Embodiments provide systems, devices, and methods for controlling a laser. The system includes a controller to control a laser, a ramp generator to ramp down laser power, the ramp generator electrically coupled with the controller and coupleable with the laser, and a hardware protection system electrically coupled with the ramp generator, wherein the ramp generator monitors signals sent from the controller and the hardware protection system to the ramp generator to detect signal failure and ramps down the laser power upon signal failure detection. The method includes sending a control status signal from a controller for a laser to a ramp generator, monitoring the control status signal for missing pulses, sending a hardware interlock status signal from a hardware protection system to the ramp generator, monitoring the hardware interlock status signal for signal failure, and ramping down laser power upon detection of missing pulses or signal failure.

Abstract: A device includes: a providing unit that provides a driving electric current to a semiconductor laser, the electric current being superimposed a first alternating current signal having a first frequency at a low side of an operational range of the semiconductor laser and a second alternating current signal having a second frequency at a high side of the operational range; a first filter that extracts a first component corresponding to the first frequency from a voltage to be applied to the semiconductor laser; a second filter that extracts a second component corresponding to the second frequency from the voltage to be applied to the semiconductor laser; and a judge circuit that judges a state of the semiconductor laser based on a first differential resistance obtained from the result of the extracting by the first filter and a second differential resistance obtained from the result of the extracting by the second filter.

Abstract: An RF powered CO2 gas-discharge laser includes discharge electrodes and a lasing gas mixture between the electrode. The lasing gas mixture is ionized when the RF power is applied to the electrodes and laser action is initiated when the RF power has been applied for a duration sufficient to ignite a discharge in the lasing gas mixture. The gas mixture is pre-ionized by periodically applying the RF power to the electrodes for a predetermined period during which ignition of a discharge is not expected to occur. RF power reflected back from the electrodes is monitored. If the monitored power falls below a predetermined level indicative of the imminent onset of laser action before the predetermined duration has elapsed, application of the RF power to the electrodes is terminated to prevent the laser action from occurring.

Abstract: A circuit for preventing destruction of a semiconductor laser element of an optical disc device comprises a light-emission-directing circuit part for outputting a light-emission-directing signal for directing the semiconductor laser element to emit light; a voltage-monitoring circuit part for monitoring a light-emitting voltage and, when a judgment is made that the light-emitting voltage is normal, outputting a light-emission-permitting signal for permitting the semiconductor laser element to emit light, the light-emitting voltage being supplied from a power source for the semiconductor laser element to an optical-output-controlling circuit part in order to cause the semiconductor laser element to emit light; and a light-emission-permitting circuit part for using the optical-output-controlling circuit part to cause the semiconductor laser element to emit light only when the light-emission-directing signal and the light-emission-permitting signal are inputted.

Abstract: A laser system with a safety protection function includes a main body and a detecting unit. The main body includes an object side portion corresponding in position to a target, and a laser-emitting module. The laser-emitting module is for providing a laser beam which is emitted at a position of the object side portion. The detecting unit is disposed at the main body, and includes a light-emitting element and a light-receiving element. The light-emitting element is for providing a light beam which is emitted at the position of the object side portion. The light-receiving element is for receiving the light beam which is reflected toward the object side portion. The laser-emitting module is prevented from emitting the laser beam when the light beam received by the light-receiving element reaches a predetermined luminous flux value.

Abstract: Aspects include electrodes that provide specified reflectivity attributes for light generated from an active region of a Light Emitting Diode (LED). LEDs that incorporate such electrode aspects. Other aspects include methods for forming such electrodes, LEDs including such electrodes, and structures including such LEDs.

Abstract: The invention concerns an optical pointing device comprising a coherent light source for illuminating a surface portion with radiation, a driver of the coherent light source for controlling coherent light emissions, a photodetector device responsive to radiation reflected from the illuminated surface portion, processing means for determining, based on the photodetector device response, a measurement of relative motion between the optical pointing device and the illuminated portion of the surface, wherein the coherent light source driver is a fault-tolerant driver comprising redundant power control means for limiting the output power of coherent light emissions.

Abstract: A pulse of laser light is switched out of a pulse train and spatially dispersed into its constituent wavelengths. The pulse is collimated to a suitable size and then diffracted by high groove density multilayer dielectric gratings. This imparts a different angle to each individual wavelength so that, when brought to the far field with a lens, the colors have spread out in a linear arrangement. The distance between wavelengths (resolution) can be tailored for the specific laser and application by altering the number of times the beam strikes the diffraction gratings, the groove density of the gratings and the focal length of the lens. End portions of the linear arrangement are each directed to a respective detector, which converts the signal to a 1 if the level meets a set-point, and a 0 if the level does not. If both detectors produces a 1, then the pulse train is allowed to propagate into an optical system.

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: In accordance with certain embodiments, an apparatus has a depletion-mode transistor electrically connected to a laser diode. The transistor provides a low impedance path for diverting electrostatic current away from the laser diode. In accordance with certain embodiments, a method for protecting a laser diode from an electrostatic charge includes providing a transistor that is electrically connected to a laser diode and has a drain and a source. The method further includes redirecting the electrostatic charge through a low impedance path from the drain to the source during a powered-on state.

Abstract: Detecting electrical overstress events in electronic circuitry such as optical emitters. In one example embodiment, a laser includes an active area and a contact region in electrical communication with the active area. A portion of the contact region is configured to manifest a change in a visual attribute of the portion in response to exposure of the portion to an electrical overstress event.

Abstract: Aspects concerning a method of making electrical contact to a region of semiconductor in which one or more LEDs are formed include that a dielectric region can be formed on a p region of the semiconductor, and that a metallic electrode can be formed on (at least partially on) the region of dielectric material. A transparent layer of a material such as Indium Tin Oxide can be used to make ohmic contact between the semiconductor and the metallic electrode, as the metallic electrode is separated from physical contact with the semiconductor by one or more of the dielectric material and the transparent ohmic contact layer (e.g., ITO layer). The dielectric material can enhance total internal reflection of light and reduce an amount of light that is absorbed by the metallic electrode.

Abstract: An electrode structure is disclosed for enhancing the brightness and/or efficiency of an LED. The electrode structure can have a metal electrode and an dielectric material formed intermediate the electrode and a light emitting semiconductor material. Electrical continuity between the semiconductor material and the metal electrode is provided by an optically transmissive ohmic contact layer, such as a layer of Indium Tin Oxide. The metal electrode thus can be physically separated from the semiconductor material by one or more of the dielectric material and the ohmic contact layer. The dielectric layer can increase total internal reflection of light at the interface between the semiconductor and the dielectric layer, which can reduce absorption of light by the electrode. Such LED can have enhanced utility and can be suitable for uses such as general illumination.

Abstract: A semiconductor laser apparatus has a Zener diode containing a first semiconductor region of a first conduction type and a second semiconductor region of a second conduction type joined with the first semiconductor region, and a vertical-cavity surface-emitting semiconductor laser diode stacked above the Zener diode and containing at least a first mirror layer of a first conduction type, a second mirror layer of a second conduction type and an active region sandwiched between the first and second mirror layers. The first semiconductor region and the second mirror layer are electrically connected and the second semiconductor region and the first mirror layer are electrically connected.

Abstract: A control circuit for a laser diode is disclosed, in which the driving current may be suppressed even when the monitor PD breaks down to make the APC feedback control inoperable. The control circuit comprises an LD driver to supply the driving current to the LD, a monitor PD to detect a portion of output light from the LD, and the APC controller to adjust the driving current. The current limiter, when the driving current reaches or exceeds the threshold, controls the driving current Id so as to keep the current in a preset value or a value just before the extraordinary increase of the driving current occurs.

Abstract: A scanning laser system has a scan position controller to control an X-Y beam translator and a beam power controller to control a light source. A processor has accessible a table having a matrix of elements representing regions having spatial coordinates in at least two dimensions. A plurality of regions is required to define a space approximately sized as a human head. Each element contains a beam power variable indicative of radiation exposure at a corresponding region. Software resident in the processor has code for receiving a value of beam power incident on each region being scanned, for incrementing a stored beam power variable for each region if the beam power value is above a predetermined threshold, and for outputting to at least one of the scan position and the beam power controller a signal indicative of each region at which the beam power variable is above a predetermined value.

Abstract: An electrode structure is disclosed for enhancing the brightness and/or efficiency of an LED. The electrode structure can have a metal electrode and an optically transmissive thick dielectric material formed intermediate the electrode and a light emitting semiconductor material. The electrode and the thick dielectric cooperate to reflect light from the semiconductor material back into the semiconductor so as to enhance the likelihood of the light ultimately being transmitted from the semiconductor material. Such LED can have enhanced utility and can be suitable for uses such as general illumination.

Abstract: A laser output power command determination value from a controller (17) is input to an upper limit current determination unit (32), and an upper limit current value to be decided based on the laser output power command determination value is determined. Then, a second comparator (30) compares a command current value determined from the laser output power command determination value and a laser output power command determination value measured with a power monitor (13), with an upper limit current value determined with a upper limit current determination unit (32). The second comparator (30) determines a command current value when the upper limit current value is greater than the command current value and the upper limit current value when the command current value is greater than the upper limit current value, as a reference current value, by which reference current value a current to be supplied to pumping means is configured to be controlled.

Abstract: A computer may include a database and a power reducing routine. The database may be configured to store an input power level of an input laser beam transmitted onto and storing power within a gain module. The database may be further configured to store a discharge power level of at least partially discharged stored power discharged from the gain module through an output laser beam. The database may also be configured to store a power safety differential limit. The power reducing routine may include an algorithm. The algorithm may be configured to calculate a power differential by subtracting the discharge power level from the input power level, and to at least one of reduce power to and shut down the input laser beam if the calculated power differential exceeds the power safety differential limit.

Abstract: A laser diode package (10) according to the present invention is tolerant of short-circuit and open-circuit failures. The laser diode package (10) includes a laser diode bar (12), a forward-biased diode (14), a heat sink (18), and a lid (16) which may have fusible links (86). The laser diode bar (12) and the forward-biased diode (14) are electrically connected in parallel between the heat sink (18) and the lid (16). The emitting region of the laser diode bar (12) is aligned to emit radiation away from the forward-biased diode (14). Several packages can be stacked together to form a laser diode array (42). The forward-biased diode (14) allows current to pass through it when an open-circuit failure has occurred in the corresponding laser diode bar (12), thus preventing an open-circuit failure from completely disabling the array (42).

Abstract: An over current protection device is described. It includes a plurality of input channels for receiving an input signal; a plurality of low pass filters coupled to a first group of the plurality of input channels, wherein each low pass filter is associated with one input channel within the first group of input channels, the plurality of low pass filters operative for removing spikes in associated with the input signal; and a plurality of digital to analog converters coupled to a second group of the plurality of input channels, wherein each digital to analog converter is associated with one low pass filter in the second group of input channels, the digital to analog converters operative for triggering over current protection when a signal received from the associated low pass filter is beyond a preset level, wherein the over current protection device is on chip with the laser diode driver.

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: A laser generator includes a generation means for pumping by a pumping light source (7) a pumping medium (3) to generate a fundamental-wave laser beam, an output sensor (6) for measuring average output power or pulse energy of the fundamental-wave laser beam, a wavelength-conversion element (5), arranged on an optical path for the fundamental-wave laser beam, for converting the fundamental-wave laser beam into its higher-harmonic-wave laser beam, and a controller (9) for memorizing a determination value set to a value lower than a breakage threshold for average output power or pulse energy of the laser beam converted by the wavelength-conversion element (5), and for, when the measurement value becomes not lower than the determination value, controlling the output power of the fundamental-wave laser beam to be a value lower than the breakage threshold; thereby, the beam intensity through the wavelength-conversion element (5) never exceeds the breakage threshold, and thus breakage of the wavelength-conversion e

Abstract: The present invention provides an auto-power control (APC) circuit and a method to stabilize the extinction ratio of an optical output from a laser diode (LD) in an optical transmitter. The APC circuit according to the invention includes two feedback loops for the modulation IM and the bias current IB each having variable loop gain. The extinction ratio of the optical output from the LD is kept constant by setting the ratio of the loop gains of respective APC circuits to be ER?1.

Abstract: A computer may include a database and a power reducing routine. The database may be configured to store an input power level of an input laser beam transmitted onto and storing power within a gain module. The database may be further configured to store a discharge power level of at least partially discharged stored power discharged from the gain module through an output laser beam. The database may also be configured to store a power safety differential limit. The power reducing routine may include an algorithm. The algorithm may be configured to calculate a power differential by subtracting the discharge power level from the input power level, and to at least one of reduce power to and shut down the input laser beam if the calculated power differential exceeds the power safety differential limit.

Abstract: In an optical supply arrangement, a laser source (10) provides transmitted laser light down an optical supply line (12, 14). A first coupler (16), remote from the laser source (10) along the optical supply line (14), taps off a small proportion of the transmitted laser light to be returned along the optical supply line (14) to a photo detector (26) driving a monitor (28) and a controller (30). If the monitor (28) detects that the photo detector (26) is experiencing a loss of return laser light, possibly due to a break in the optical supply line (14), the monitor (28) causes the controller (30) to extinguish the laser source (10) in less time than escaping laser light can cause damage to property, person or eyesight. A first embodiment has the transmitted light on a transmission fiber optic (12) and the return laser light on a separate return fiber optic (24). A second embodiment has the return laser light being sent back down the transmission fiber optic (12).