1.2: Speckle suppression method using high‐frequency driving current to semiconductor laser diode

Suppression of speckle noise is a key issue in the development and utilization of laser display and illumination. Many approaches to reduce the speckle contrast in laser display systems have been proposed and developed. A practical high frequency laser driver circuit is designed and developed to drive green semiconductor lasers. Speckle contrast under different driving frequencies from 100Hz to 15Mhz was tested by using a speckle contrast measurement system, the speckle contrast of green laser decreased from 13.35% to 5.23%. The results show that the modulation of high frequency current of the semiconductor laser diode will destroy the coherence of the laser light and reduce the speckle contrast. The effectiveness of this method to depress speckle noise was verified.