A pulsed laser system includes a laser pump (14), a laser rod (12), a reflector (18) interposed between the laser pump and the laser rod, through which energy from the laser pump enters the laser rod, an output reflector (28) through which energy is emitted from the laser rod, a switch (20) interposed between the laser rod and the output reflector, and a control device. The control device allows a primary laser pulse emitted from the laser rod during the emission period to impinge on a workpiece and blocks from the workpiece secondary laser emission occurring during the emission period after emission of the primary pulse. The pulsed laser system is operated over a range of repetition rates, so as to cause laser energy emitted during plural emission periods at each repetition rate. A portion of the laser energy emitted is directed toward the target structure.

Pulse control in laser systems

An illumination system (10, 40, 74, 100) is provided having one or more light sources (24, 26), opaque baffles (30, 32), and mirrors (50, 64, 66) for illuminating indicia on a substrate, such as a semiconductor wafer (18), for viewing by a camera (12, 42) aligned parallel to or at an angle (14) to the substrate. The light sources (24, 26) include light emitting diodes for illuminating soft marks and broad spectrum incandescent lamps for illuminating hard marks. Dark field and light field illuminators are provided for enhanced reading of light indicia on a dark background and dark indicia on a light background, respectively. A light control unit (158) allows for manual or automated control of light source selection and light intensity. Opposing mirrors extending along the optical paths of the light sources reflect light emitted from the light sources into the camera's field of view, thereby increasing the illumination efficiency and permitting the use of fewer light sources.

Illumination system for ocr of indicia on a substrate

An intracavity modulated pulsed laser and methods of using the same. In one preferred form, an intracavity modulated pulsed laser comprises an amplification medium, a pulsed pumping source, a beam modulator, and two mirrors, one totally reflective and one partially reflective for generating at least one laser output burst comprising a plurality of sub-pulses having variably controllable peak powers. In another preferred form, a non-linear crystal is utilized to double the frequency of each laser output burst. In still another preferred form, a fluorescence feedback control circuit is utilized to control the beam modulator.

Intracavity modulated pulsed laser and methods of using the same

A pulsed-laser includes a pump-light source, a gain-medium and a Q-switch. The Q-switch has an on-mode in which it is substantially transparent, and an off-mode in which it is normally substantially opaque. A gate-signal switches the laser between a ready-mode in which no pulses are delivered and a pulse-drive mode in which pulses are delivered. A first-pulse controller is provided for controlling the energy in the first of a series of pulses to be delivered by the laser. The first-pulse controller controls the first pulse energy by operating one or more of the Q-switch and the pump-light source in such a way that after switching from the ready-mode to the pulse drive mode the energy in the gain-medium at the instant of triggering the first pulse in the series of pulses is about the same that which will be reached in the gain-medium prior to triggering of subsequent pulses in the series. In this way, all pulses in the series have the about the same energy. Operation of the Q-switch may include raising its transmission value during its off-mode to allow a relatively low level of laser action for depleting energy stored in the gain-medium.

Pulsed-laser with first-pulse control

A laser processing apparatus includes a laser beam source, a focusing optical system for focusing a laser beam from the source as a processing laser beam to a surface of an article, an illuminating optical system using a laser beam of the same frequency as that of the processing laser beam as an illumination laser beam for illuminating the surface of the article, and a photographing device for detecting the illumination laser beam reflected from the article through the focusing optical system to thereby monitor a position to be processed. Since the laser beam of the illuminating optical system is of the same frequency as that of the processing beam chromatic aberration is prevented. This allows increased monitoring accuracy so that an article such as copper foil can be processed by a laser beam with an accuracy of 10 microns to monitor and correct a processing position.

Apparatus for laser processing and monitoring

The Q-switched laser gating pulses of an acousto-optic Q-switch are synchronized electrically to the phase of the RF signal driving the Q-switch by applying the RF oscillator output signals to the clock input of an integrated circuit D-type flip-flop and the laser gating pulses to the D input of the flip-flop, whereby the leading edge of each output gating pulse from the flip-flop always occurs at a particular place on the RF waveform In another embodiment, the RF signals are synchronized to the phase of the gating pulses by applying the output of a repetition rate oscillator to the RF oscillator

Q-switched laser with stable output and method of making the same

Verfahren und einrichtung zum stabilisieren der laserausgangsimpulse eines guetegeschalteten lasers

L'INVENTION CONCERNE LA STABILISATION DES LASERS A MODULATION DU FACTEUR DE QUALITE. SELON L'INVENTION, LES IMPULSIONS DE DECLENCHEMENT DU LASER SONT SYNCHRONISEES ELECTRIQUEMENT SUR LA PHASE DU SIGNAL A HAUTE FREQUENCE QUI PILOTE LE MODULATEUR, PAR APPLICATION DES SIGNAUX DE L'OSCILLATEUR A HAUTE FREQUENCE 40 A L'ENTREE D'HORLOGE D'UN BASCULEUR 44 QUI RECOIT LES IMPULSIONS DE DECLENCHEMENT D'UNE SOURCE 36, TRANSMISES PAR L'INTERMEDIAIRE D'UNE PORTE 34 COMMANDEE PAR UN OSCILLATEUR 32 A FREQUENCE DE REPETITION. D'AUTRES SYNCHRONISATIONS DES SIGNAUX SONT POSSIBLES SELON L'INVENTION. APPLICATION AUX LASERS A MODULATION DU FACTEUR DE QUALITE.

Mauck Michael S

Papers

Q-switched laser with stable output and method of making the same

Verfahren und einrichtung zum stabilisieren der laserausgangsimpulse eines guetegeschalteten lasers

Laser a modulation du facteur de qualite et son procede de stabilisation