SENSOR FOR A LASER BEAM TARGET

摘要

A sensor for a laser beam target which is comprised of at least one lateral effect photodiode, such that a beam of light from a laser can be focused upon the photodiode. The photodiode has a left half and a right half. A first circuit is connected to the left half of the photodiode and a second circuit connected to the right half of the photodiode. Each circuit has the following components. A transimpedance amplifier is connected to one half of the photodiode, such that the beam of light striking the half of the photodiode is converted to voltage levels. A resistor is connected to the transimpedance amplifier thereby determining a dynamic range of voltage such that voltage levels within the range result in a positive value and voltage below the range result in a value of zero. A unipolar differential amplifier is connected to the transimpedance amplifier. The differential amplifier in the first circuit is linked with the differential amplifier in the second circuit, such that when the beam of light from the laser is to the left or right of centre a voltage of a positive value is generated in one or the other of the differential amplifiers. A voltage comparator is connected to the differential amplifier thereby setting limits which define the physical centre of the photodiode and altering the voltage in the circuits when the beam of light from the laser is positioned within the limits of physical centre. Signal means is provided for indicating to the operator the positioning of the beam of light from the laser.