Patent ID: 7920610

Claim:
A method of operating a frequency-converted laser source comprising a laser diode optically coupled to a wavelength conversion device for conversion of a pulsed optical signal generated by the laser diode, wherein: the laser diode is driven in a pulsed mode to define pixel intensity values corresponding to desired gray scale values of image pixels in an image plane of the laser source; the pixel intensity values are a function of a laser control signal comprising a discontinuous pulse component, a relatively constant intensity component I, and a continuously variable intensity component I*; the pulse width w of the discontinuous pulse component is selected from a set of discrete available pulse widths according to a desired pixel gray scale value; a low-end pulse width w of the set of available pulse widths is established for a range of low-end pixel gray scale values; progressively larger pulse widths w are established for ranges of progressively higher pixel gray scale values; the relatively constant intensity component I makes a relatively insignificant contribution to pixel intensity at the low-end pulse width w for the range of low-end pixel gray scale values and assumes a non-zero value for enhanced conversion efficiency at the progressively larger pulse widths w established for the higher pixel gray scale values; and the continuously variable intensity component I* varies according to the desired gray scale value of the selected pixel and the contributions of the relatively constant intensity component I and the pulse width w to pixel intensity.