Laser power control arrangements in electro-optical readers

A laser power control arrangement for regulating output power of a laser beam emitted by a laser in an electro-optical reader for reading indicia, comprising:

• a laser drive circuit for energizing the laser a plurality of times at substantially the same first temperature in a calibration mode to emit the laser beam with different, first and second output powers that respectively correspond to different, first and second, calibration drive currents, and for energizing the laser a plurality of times at substantially the same second temperature in an operating mode to emit the laser beam with the same first and second output powers that respectively correspond to different, first and second, operating drive currents;
• a memory for storing a calibration difference between the first and second, calibration drive currents, the calibration difference being resistant to variations in the first temperature in the calibration mode, and the memory being further operative for storing an operating difference between the first and second, operating drive currents, the operating difference being resistant to variations in the second temperature in the operating mode;
• and
• a controller operative in the operating mode for comparing the operating difference between the first and second, operating drive currents with the calibration difference between the first and second, calibration drive currents to resist variations between the first temperature and the second temperature, and for deenergizing the laser when the operating difference exceeds the calibration difference by a predetermined amount.