Laser marker focal length setting device

A method of adjusting the distance between a movable laser output of a laser marking apparatus and an item to be laser marked, the apparatus having a sensor mounted in a fixed relation to the output, wherein the sensor is adapted to sense the distance and to provide a human-perceivable indication of the distance, the method comprising the steps of:

• mounting at the output a focussing lens having a focal length;
• varying the distance between the sensor and the item to be laser marked by moving the output;
• observing the human-perceivable indication of the distance while varying the distance between the sensor and the item to be laser marked;
• and
• fixing the distance by fixing the output when the human-perceivable indication of the distance corresponds to a desired distance.

A laser marking apparatus comprising:

• a movable laser output;
• an item position occupiable by an item to be marked;
• a distance sensor stationarily mounted with respect to the laser output, and sensingly mounted with respect to the item to be marked when occupying the item position;
• and
• a human-perceivable distance output communicably linked to an output of the distance sensor.

An apparatus for setting a distance between a movable laser output of a laser marking apparatus and an item to be laser marked, comprising:

• a sensor mounted in a fixed relation to the movable laser output, wherein the sensor is positioned to sense a distance corresponding to the distance between the movable laser output and the item;
• a signal sensor circuit including (1) a set of sensor processors, communicatively coupled to a signal output from the sensor, each responsive to a turn-on signal value for the signal output, each having a sensor processor control output, (2) a control input to effect selection of one of the set of sensor processors, and (3) a distance control output, selectively coupled to one of the sensor processor control outputs, indicating when the signal output reaches the turn-on signal value of the selected sensor processor;
• a selection mechanism having a selection control output communicatively coupled to the control input of the signal sensor circuit;
• and
• a laser actuator communicatively coupled to the distance control output and physically attached to the movable laser output, the laser actuator including circuitry responsive to the distance control output, thereby effecting automatic positioning of the movable laser output at a distance from the item according to the selection mechanism.