Abstract: A laser beam machining apparatus forms blind holes at predetermined intervals in a workpiece by intermittently irradiating a laser beam from a laser nozzle to the workpiece while the laser nozzle and the workpiece being moved relatively. During the time the workpiece is subjected to machining, the electrostatic capacity between the support member and the laser nozzle is detected by an electrostatic capacity sensor while the workpiece made of conductive material is supported on the support member. The irradiation output power is controlled by a control unit which operates to vary the number of output pulses from the laser nozzle each time one hole is formed according to the result detected in response to variation in the thickness of the workpiece.

Abstract: The present invention relates to the use of a laser to remove surface contamination and oxidation from a ball grid array substrate. The laser etching can be configured to cover the entire substrate or pinpointed to the epoxy molding compound/solder resist (EMC/SR) interfaces. Additionally, a laser can be used to roughen the surface of a substrate to provide better adhesion when attaching the die to the substrate.

Abstract: A marking device for the creation of an optical mark onto an object has a laser connected to a power supply unit to create a laser beam and a speed acquisition device for determining a positioning speed at which the laser beam follows a repetitive pattern upon the object. The power supply unit has a controlling unit connected to the speed acquisition device which controls the intensity of the laser beam based upon the positioning speed. When the positioning speed decreases the lower predetermined value, the laser beam power is reduced and, if the positioning speed decreases below a minimum positioning speed, the laser beam is switched off.

Abstract: A method and system for locally processing a predetermined microstructure formed on a substrate without causing undesirable changes in electrical or physical characteristics of the substrate or other structures formed on the substrate are provided. The method includes providing information based on a model of laser pulse interactions with the predetermined microstructure, the substrate and the other structures. At least one characteristic of at least one pulse is determined based on the information. A pulsed laser beam is generated including the at least one pulse. The method further includes irradiating the at least one pulse having the at least one determined characteristic into a spot on the predetermined microstructure. The at least one determined characteristic and other characteristics of the at least one pulse are sufficient to locally process the predetermined microstructure without causing the undesirable changes.

Abstract: Embodiments of methods and an apparatus for creating points or areas of laser-induced damage inside a transparent material are disclosed. One or more embodiments of the invention comprise a method and system for producing etch points by control of breakdown process development. In one embodiment, at the beginning an applied laser radiation level just exceeds an energy threshold for creating a plasma condition in the material, and thereafter the energy level of the applied laser radiation is just maintain the plasma condition and is applied before the plasma condition extinguishes, but after a shock wave associated therewith has passed. Other embodiments of the invention comprise a method and a system for producing etch points by controlling a space structure of laser beam. According to the invention a laser generates a TEMmnm radiation. The values of the integers m and n are controlled and determined so as to reproduce particular gray shades for a particular point of an image.

Abstract: A control system is provided for a laser-equipped machine tool which is capable of preventing self-burning. The temperature of the workpiece proximate the cut is monitored, and a numerical control compares the actual workpiece temperature to a prestored temperature limit, empirically determined, which is predictive of the onset of self-burning. If the workpiece temperature approaches or reaches the limit, an abort signal is generated. Upon generation of an abort signal the control processor deenergizes the laser to prevent commencement of self-burning. In addition the processor stores the cutting parameters and the coordinate locations of the aborted cut, so that the processor can later return to finish the cut, and sets a cool-down timer. The processor then causes movement to a next available cutting position, tests the temperature at that position, then commences cutting.

Abstract: An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser having a first wavelength for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a fiber amplifier subsystem for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses.

Abstract: The invention relates to a device for influencing a laser beam by means of an adaptive mirror (12) in the beam path, having a piezoelectric adjusting member (17) arranged on the back of the mirror (12), it being the case that, in order to achieve low-aberration deformation of the mirror (12) for the purpose of influencing the divergence of the beam, there is provided between the adjusting member (17) and the back (24) of the mirror (12) a pressure-transmitting device (19) which acts on a large area of the deformable surface of the mirror (12).

Abstract: This is to present a laser machining method and a laser machining apparatus for drilling holes, capable of achieving conduction securely between adjacent conductive layers, by detecting the machining state of a workpiece adequately, and controlling the machining. For this purpose, the number of laser pulse outputs capable of machining securely is preset. During laser machining, reflected laser beam intensity from the workpiece and incident laser beam intensity are detected, and the machining state of the workpiece is detected. As a result, when judging the workpiece has reached a desired machining state, laser machining is finished if the number of times of laser machining has not reached the set number of laser pulse outputs. If it is judged that the workpiece has not reached the desired machining state, laser machining is finished when reaching the set number of laser pulse outputs.

Abstract: There is described a laser processing device (1) whereby, by means of laser light (6), a workpiece (4) can be processed and wherein, at the same time, an image of the workpiece (4) to be processed is obtained, wherein the focusing of the imaging optics is independent of the focusing of the laser optics. The device (1) comprises a stationary laser mirror (21) and laser focusing optics (22), which laser focusing optics (22) are axially displaceable relative to the laser mirror (21). The device (1) further comprises imaging optics (23) which are al axially displaceable relative to the laser mirror (21), such that the axial distance between the laser focusing optics (22) and the imaging optics (23) is constant.

Abstract: Motorized slides are inserted between the end of a robot arm and a robot tool/sensor arrangement to provide additional positioning ability. A control unit of the slides cooperates with the control unit of the sensor to maintain the tool correctly positioned over a feature while the robot arm moves following a programmed path. The control unit of the sensor has look-ahead and additional buffers from which corrected information is determined to compensate for robot teaching inaccuracies, calibration and robot arm response errors. A sensor with two distinct probing zones is used to get information about the position of the tool tip and of the feature to assist in calibrating the sensor/tool relation.

Abstract: Methods, systems, and apparatus consistent with the present invention use laser energy for thermally processing a quartz object using a beam of laser energy. Once placed in a configuration where the laser beam can be applied to an exterior surface of the quartz object, one or more laser beams are applied to a starting point on the surface. The laser beams may have the same or different wavelengths, energy levels and/or focal lengths. As the surface is heated by the laser energy, the surface is eventually pierced by the beam and a channel forms within the quartz object. As the channel deepens to access an inner portion of the object, the energy of the beam is altered to thermally process or selectively heat the inner portion. After processing the inner portion, the channel is typically closed by fusion welding the walls of the channel (or the channel and quartz filler material) using the beam.

Abstract: A method and apparatus is disclosed for forming lines of weakness in an automotive trim piece so as to enable formation of an airbag deployment opening in the trim piece. A cutting beam, such as a laser is directed at the trim piece surface to be scored and a sensor emits a sensing beam, and a beam combining device receives both the sensor beam and the laser beam and causes downstream beam segments to be collinear with each other as they impinge the trim piece surface. The scoring is thereby able to be carried out in a single pass, and is precise, repeatable and independent of cutting depth, angle of cutting, scoring patterns, material inconsistency, material color, and surface grain variability.

Abstract: A heavy-duty laser plate cutting machine capable of cutting heavy plate at production rates. The machine includes a laser source having an output power of 4 kilowatts or more. The machine is preferably of the flying optic configuration, and an automatic beam control system, such as an automatically adjustable collimator is interposed between the laser source and a focusing optic carried in the cutting head. The cutting head, in addition to normal Z-axis control, has an adjustment to position the focal spot relative to the workpiece. The focal spot can be driven into the workpiece when cutting heavy plate. A machine bed underlying the workpiece is capable of absorbing significant energy from the remnant laser beam without damaging the machine base.

Abstract: Cleaning and inspecting a surface of the substrate comprises subjecting the surface to the output of a laser source for applying a cleaning energy to the surface and thereby remove contaminants on the surface. The laser source is used for inspecting the surface being cleaned and to measure the effect of the cleaning.

Abstract: A method and apparatus for real time control of laser beam characteristics in a high power laser-equipped machine tool. A beam path input signal is produced related to changes in the length of the laser beam path as the processing head of the machine tool moves over the workpiece. An integrator produces a signal related to the real time changes in thermal loading of the laser output coupler as the laser beam is applied and as the output power level is adjusted. The beam path and thermal loading signals are used to drive a collimator so as to correct in real time for altered beam characteristics introduced by path length changes and thermal lensing of the output coupler. The result is to maintain control of the beam size at the focus optic. In addition, a further integrator produces a signal related to the real time changes in thermal loading of the focal optic as the laser beam is applied and as the input laser power level is adjusted.

Abstract: A method for controlling the laser texturing of a magnetic disk by using a texturing laser system to create texturing bumps and an analyzing laser system to determine texture bump height and to provide feedback to the texturing laser system. From an angular distribution of an array of diffracted light intensities of the texturing bumps, the intensity of a first diffraction peak (Int1) and its array position (P1) are determined and utilized to calculate the average bump height h according to the equation: h=A/P1+B(Int1)+C where A, B and C are constants that are determined for a batch of disks by taking a representative sample of disks and texturing them with differing laser energies within the energy level range.

Abstract: The invention relates to fused silica having low compaction under high energy irradiation, particularly adaptable for use in photolithography applications.

Abstract: In a power monitor mode, during the laser oscillation output there are fetched laser output measured values, lamp voltage measured values and lamp current measured values (step J1), and energy of each pulse is figured out on the basis of time integral value of the laser output measured values (step J2). Then, at a certain time Ta interval, an energy average value and a laser output average value are figured out for display based on the cumulative value of the energy of each pulse, and a lamp power average value QM and a lamp power input ratio KM are found by calculation from the cumulative value of the lamp power (SV·SI) of each pulse (step J5). In OFF display mode the lamp power input ratio KM appears. Under the laser output feedback control, the lamp power input ratio KM gradually goes up according as the deterioration with time increases within a laser oscillation unit.

Abstract: An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a laser amplifier for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses.

Abstract: This invention is directed toward a method of calculating the total laser energy needed to produce one or more selected laser induced surface modification reactions in a substrate moving relative to a laser beam. The present invention is further directed to a method for programming a programmable feedback control system with the calculated total laser energy such that the control system may be used to control laser beam power level and beam width in a process for producing a laser induced surface modification.

Abstract: An energy beam method and apparatus for processing a workpiece is accomplished by making the energy density per unit time and unit area of the energy beam proportional to the traveling velocity of the workpiece. This is accomplished by adjusting the frequency, irradiation power, or duty cycle of the energy beam. The travel velocity of the workpiece is measured by using a linear scale to generate pulse signals, calculating a traveling velocity based on the pulse signals and generating a pulse signal, dividing the pulse signals output by the calculation step, and generating a trigger signal in response to the pulse signals created by the dividing step to drive an energy beam irradiation device (such as a laser generator) to output the energy beam.

Abstract: In a laser welding, a laser beam is focused on a workpiece by a focusing lens or lenses. The focusing lens or lenses image an aperture liming the size of the laser beam on the workpiece and the size of focused laser beam is the image size of the aperture on the workpiece at the wavelength of the laser. A weld pool is generated by the interaction of the focused laser beam and the workpiece. Due to the thermal conduction of the workpiece, the size of the weld pool is generally not the same as the size of the focused laser beam and varies with the power of the laser or with the focus shift of the focusing lens or lenses. The weld pool radiates a thermal radiation. An apparatus and method is disclosed wherein the thermal radiation is measured back through the focusing lens or lenses and through the aperture limiting the size of the laser beam or any other aperture limiting a size of the thermal radiation to be measured in at least three spectral bands with single element detectors.

Abstract: An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser having a first wavelength for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a fiber amplifier subsystem for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses.

Abstract: An airbag cover and method is disclosed. The cover comprises a laminate formed from a thermoplastic substrate base layer, a foamed thermoplastic intermediate layer and a thermoplastic decorative foil layer, wherein a panel for permitting release of an airbag is outlined in the cover by laser cuts extending into the laminate from said base layer, said laser cuts having a substantially uniform depth into the laminate.

Abstract: Embodiments of methods and laser system for creating laser-induced damages inside a transparent material are disclosed. One or more embodiments of the invention comprise a method and system for production of an etch point by generating breakdowns in several separate focused small points inside the etch point area. Other embodiments of the invention comprise a method for production of etch points which have the same size but different brightness. Laser-induced damages produced by this method permit to reproduce image gradation without changing of their spatial resolution. According to the invention it is made by variation of a number of focused small points inside an etch point area. Other embodiments of the invention comprise method for creation of an etch point with desirable form. Using such etch points it is possible to produce images which from different directions will have right brightness.

Abstract: Cleaning a media surface, such as a disc surface, comprises subjecting the surface to a detector for sensing the nature of the surface for an irregularity in the smoothness of the surface. Directing, on detecting an irregularity beyond a predetermined amount, a burnishing pulse laser output to that irregularity, and energizing the laser to thereby impart an energy source to reduce the irregularity to a degree less than a predetermined amount.

Abstract: A device for machining a hole or a shape of varying profile in a mechanical workpiece using an excimer laser comprises a screen having an aperture of predetermined shape disposed between the excimer laser and a device for focussing the laser beam, the screen being movable in a plane perpendicular to the laser beam. Control means is provided for automatically controlling displacement of the screen in real time while the hole is being machined in the workpiece, the control being effected as a function of the number of pulses emitted by the excimer laser. As an alternative, the screen may be replaced by a diaphragm comprising variable-aperture shutters.

Abstract: A laser cutting system has a specially designed frame that allows the laser cutting head to be mounted to the underside of a cross beam for a more efficient movement. The frame is further designed so as to allow the accessing of the work area of the laser cutting system along three different directions. The movement of the laser cutting head for fabricating a sheet placed in the work area of the laser cutting system is effected by a process that takes into consideration a number of parameters and determined data all of which are interpolated for generating optimal movements to further enhance the operating efficiency of the laser cutting system. The laser resonator of the laser cutting system of the instant invention is configured to have a telescopic system that maintains the density and power of the laser beam by auto focusing the same so that optimum cuts can be effected irrespective of whichever area of the worksheet is to be fabricated.

Abstract: A method and apparatus for quality control of laser shock processing. The method includes measuring emissions and characteristics of a workpiece when subjected to a pulse of coherent energy from a laser. These empirically measured emissions and characteristics of the workpiece are correlated to theoretical shock pressure, residual stress profile, or fatigue life of the workpiece. The apparatus may include a radiometer or acoustic detection device for measuring these characteristics.

Abstract: A maskless patterning apparatus allows for laser beam ablation of one or more layers of material while not etching an underlying different material layer. A micromirror array produces the desired complex pattern on the workpiece and a continuous feature and end point detection system provides location and material parameter changes to accurately control the pattern position and depth of etching. End point detection includes monitoring energy reflected from a specially prepared replica of the material to be ablated, whose thickness and consistency match the active workpiece area. The process terminates when the proper amount of material is removed.

Abstract: A laser annealing apparatus has a laser generating section for producing a laser beam, a splitter arranged to partially reflect and partially transmit the laser beam. The apparatus has a first energy converting section for measuring the energy value of the laser beam reflected from the splitter and outputting it into an electrical signal and has an energy control section for comparing the output signal of the first energy converting section to a reference value and automatically correcting the energy value by the difference between them. A process window may be positioned so the laser beam can pass through a built-in slit for annelaing a substrate. The apparatus further has a second energy converting section for measuring the energy value of the laser beam passing through the process window. In response to the output of the second energy converting section, the energy control section corrects the energy intensity of the laser beam.

Abstract: This is to present a laser machining method and a laser machining apparatus for drilling holes, capable of achieving conduction securely between adjacent conductive layers, by detecting the machining state of a workpiece adequately, and controlling the machining.

Abstract: An energy-efficient method and system for processing target material such as microstructures in a microscopic region without causing undesirable changes in electrical and/or physical characteristics of material surrounding the target material is provided. The system includes a controller for generating a processing control signal and a signal generator for generating a modulated drive waveform based on the processing control signal. The waveform has a sub-nanosecond rise time. The system also includes a gain-switched, pulsed semiconductor seed laser for generating a laser pulse train at a repetition rate. The drive waveform pumps the laser so that each pulse of the pulse train has a predetermined shape. Further, the system includes a laser amplifier for optically amplifying the pulse train to obtain an amplified pulse train without significantly changing the predetermined shape of the pulses.

Abstract: A laser shock peening system includes an apparatus and method that senses a thickness of laser transparent confinement media flow, such as water. In one embodiment, the apparatus indicates a proper thickness, in another embodiment, the apparatus controls the flow rate of the confinement media using signals from probes of the apparatus. A first probe is used to sense a predetermined minimum thickness and another embodiment further includes a second probe to indicate a predetermined maximum thickness of the confinement media.

Abstract: There is provided a thin film semiconductor device capable of uniforming characteristics of semiconductor elements which use a polycrystalline silicon film formed by laser annealing as an active layer. A polycrystalline silicon film in which an &agr;-region and &bgr;-region are alternately distributed on a glass substrate is formed by laser annealing of scanning a laser beam having a rectangular cross-section shape. Silicon islands of transistors to be used for a data line drive circuit, silicon islands of transistors to be used for a sampling circuit, silicon islands of transistors to be used for a logic circuit, silicon islands of transistors to be used for a scan line drive circuit, silicon islands of transistors to be used for an amplifier circuit and silicon islands of transistors of a pixel electrode use switching circuit are formed in &bgr;-regions in which the polycrystalline silicon film has an approximately equal size of surface unevenness.

Abstract: A substrate removal approach involves sensing acoustic energy in a semiconductor device as a function of substrate thickness in the device as substrate is being removed. According to an example embodiment of the present invention, a semiconductor chip having substrate at a back side that is opposite circuitry at a circuit side is analyzed. Some or all of the substrate in the back side of the semiconductor chip is removed, and a thinned region having a bottom area is formed. A laser is directed to the bottom area, and a thermal parameter characterizing target circuitry in the device is detected in response to the laser. The detected parameter is used and an indication of the remaining substrate thickness between the bottom area and the circuitry is determined. In response to the indicated thickness, the substrate removal process is controlled, making possible effective control of the substrate removal process.

Abstract: This invention relates to a lens machining device for machining a lens so that the optical characteristics of light outputted by a semiconductor laser element (10) will be adjusted to desired ones. The lens (12) to be machined is provided at one end of the element (10) and the optical characteristics of the lens (12) are measured with a wave front measuring instrument (16) through the use of the light transmitted through the lens (12). A machining laser beam is focused upon the surface of the lens (12) through a beam splitter (14). The surface of the lens (12) is machined with the laser beam while a position adjusting device (22) adjusts the relative positional relation between the surface of the lens (12) and a position where the laser beam is focused. An ultraviolet laser (18) and the position adjusting device (22) are controlled by a controlling arithmetic device (24).

Abstract: A multiplicity of laser diodes aim laser light directly onto the surface of a workpiece and are disposed over and according to the to-be-shaped contour of a workpiece, so that a detector unit for determining the spatial shaping of the workpiece and an evaluation and control unit can determine process parameters for further illumination in dependence on a comparison of an actual state of shaping and a desired state of shaping of the workpiece.

Abstract: An apparatus for measuring an optical characteristic of an ablation standard object having a known ablation rate, as compared with an object to be processed having a unknown ablation rate which is ablated with laser beam, the apparatus comprising a retaining device for retaining the ablation standard object so that a surface thereof may be at the predetermined height, a refractive power measuring device for measuring a refractive power of the ablation standard object, which includes a projecting optical system for projecting target luminous flux for use in refractive power measurement onto the ablation standard object retained by the retaining device and a detecting optical system for detecting the target luminous flux projected by the projecting optical system, a moving device for moving the refractive power measuring device to the predetermined measuring position in order to measure the refractive power of the ablation standard object, and an output device for outputting results measured by the refractive p

Abstract: The penetration depth of a machining laser beam into workpiece is continuously monitored in that a measuring laser beam is directed onto the vapor capillary that is generated in the workpiece by the machining laser beam.

Abstract: Methods and apparatus for forming three-dimensional objects from a medium solidifiable when subjected to a beam of pulsed radiation wherein the pulses of radiation are made to occur when the beam is directed to desired pulsing locations on a target surface of the medium. Preferred embodiments of the instant invention include a pulsed laser assembly, including a laser and a pulse generation circuit, a control computer, a plurality of mirrors and mirror encoders. The computer controls the movement of the mirrors which guide the laser beam across the surface of the solidifiable medium. The pulsing of the laser beam is correlated to the position of the mirrors and thus, is not dependent upon time. Pulsing linked to position of beam placement allows controlled and repeatable use of a pulsed beam for the formation of objects.

Abstract: To provide parts soldering apparatus and method which improve the productivity during parts soldering and increase the mounting accuracy of parts on a circuit board. The parts soldering apparatus of the present invention has: a stage for positioning a circuit board whereon, the circuit board is mounted a solder tip whereon; a loading arm made of a light-transmitting material, for loading a part onto the solder tip; a fluctuating mechanism for pressing the loading arm toward the circuit board; and an optical source for irradiating light onto the part through the loading arm and for melting the solder tip by the conductive heat of the light irradiated onto the part.

Abstract: This invention relates to a dynamic laser cutting apparatus for cutting successively various configurations on a moving feed stock or other moving web or successive sheets. The apparatus includes a control device, which monitors the relative location of the moving feed stock, and controls a scanner to direct a laser beam to cut successively various configurations on the desired relative location of the feed stock. One of the configurations that may be cut with the present invention is sets of successive sheets with index tabs in different locations, from a high-speed moving feed stock, thereby eliminating the need for collating the individual index tab sheets into a set. In order to cut consistently, the control device also monitors the speed of the moving feed stock, and based on the speed of the feed stock, adjusts the power level of the laser to cut consistently on the moving feed stock.

Abstract: An improved method for operating a steered laser beam system employs selective laser power control. A laser beam is provided having a selectively positionable focal point. A workpiece is provided on which a selected laser beam pattern is used to process the workpiece, and the laser beam focal point is controlled to travel along the selected pattern at varying velocities. A position of the focal point on the workpiece is dynamically determined as the focal point travels along the selected pattern. A velocity of the focal point on the workpiece is dynamically calculated based on multiple determined positions of the focal point. An energy level of the laser beam is controlled based on the calculated velocity of the focal point. In one embodiment, the energy level of the laser beam is adjusted to maintain a constant energy per unit distance traveled by the focal point.

Abstract: A Q-switched solid state laser system (24) operates in a pulse processing control system (10) that employs an autopulse mode and a pulse-on-position mode to stabilize the pulse-to-pulse laser energy delivered to a workpiece (20) that is moved by an X-Y positioner (18). In the autopulse mode, laser pulses are emitted at a near maximum PRF, but the pulses are blocked from reaching the workpiece by an external modulator (28, 32), such as an acousto-optic modulator (“AOM”) or electro-optic modulator (also referred to as a Pockels cell). In the pulse-on-position mode, the laser emits a pulse in response to the positioner moving to a location on the workpiece that coincides with a commanded coordinate location. The processing control system delivers a stream of coordinate locations, some requiring processing, at a rate that moves the positioner and triggers the laser at about the near maximum PRF.

Abstract: A laser output detector is provided which comprises: a convertor unit having a light sampling port to be located adjacent a projecting portion of a laser beam projector for sampling a fraction of a convergent portion of a laser beam projected from the laser beam projector or a fraction of a non-convergent portion of the laser beam outside the convergent portion of the laser beam, and adapted to convert the sampled laser beam fraction into an electrical signal; and a detection circuit for computing the energy amount of the projected laser beam on the basis of the electrical signal outputted from the convertor unit.