Noise resistant laser system for machine alignment

A noise resistant laser system for machine alignment, comprising:

• a semiconductor laser emitting a narrow collimated light beam onto a target;
• a photodetector target receiving said light beam from said laser, said target producing four output signals which are indicative of a laser beam spot displacement on said target;
• a display unit operatively connected to said target for processing said output of said target to enable an operator to perform said alignment;
• and a noise suppressing means for removing influence of industrial power supplies, lighting and their harmonics on said display unit, said noise suppressing means including:
• an oscillator for generating a train of pulses at a predetermined frequency distinguishable from industrial power source frequencies and harmonics thereof, a laser power supply fed by said oscillator for pulsing said laser light beam at said predetermined frequency, said laser power supply comprising an interrupter, a laser current control circuit, and a synchronous feedback control circuit, said interrupter being controlled by said oscillator, said synchronous feedback control circuit being fed from said oscillator and from said laser, and said laser current control circuit being fed by said interrupter and said synchronous feedback control circuit and being connected across said laser to govern a said laser emission level and a filter fed by said four target output pulse signals and said oscillator for sorting out components from said target output pulse signals due to said laser light beam, said components being input signals for said display unit.

A noise resistant laser system for machine alignment, comprising:

• a semiconductor laser emitting a narrow collimated light beam onto a target;
• a photodetector target receiving said light beam from said laser, said target producing four output signals which are indicative of a laser beam spot displacement on said target;
• a display unit operatively connected to said target for processing said output of said target to enable an operator to perform said alignment;
• and a noise suppressing means for removing influence of industrial power supplies, lighting and their harmonics on said display unit, said noise suppressing means including:
• an oscillator for generating a train of pulses at a predetermined frequency distinguishable from industrial power source frequencies and harmonics thereof, a laser power supply fed by said oscillator for pulsing said laser light beam at said predetermined frequency, and a filter fed by said four target output pulse signals and said oscillator for sorting out components from said target output pulse signals due to said laser light beam, said filter comprising a sample and hold circuit, said components being input signals for said display unit.

A noise resistant laser system for machine alignment comprising:

• a semiconductor laser for producing a narrow collimated beam;
• a photodetector target for receiving the beam and producing four output pulse trains which are indicative of the horizontal and vertical displacements of the laser beam on the target;
• a crystal controlled oscillator for generating pulses at a frequency which is distinguishable from noise generated by industrial power supplies, lighting and their harmonics;
• a closed loop control circuit for pulsing the laser at the distinguishable frequency;
• a sample and hold circuit for sorting out components due to the beam displacement and suppressing components due to industrial power supplies;
• and a display unit, said closed loop control circuit being comprised of an interrupter, a feedback control circuit and a laser current control circuit, said interruper and the feedback control circuit being controlled by said oscillator, said feedback control circuit being responsive to the emission level of the laser to maintain a constant average emmision level, said display unit processing output signals from said sample and hold circuit to enable an operator to perform the alignment.