A former judge convicted of exposing himself while presiding over jury trials by using a sexual device under his robe was sentenced Friday to four years in prison. Donald Thompson had spent almost 23 years on the bench and had served as a state legislator before retiring from the court in 2004. He showed no reaction when he was sentenced. At his trial this summer, his former court reporter, Lisa Foster, testified that she saw Thompson expose himself at least 15 times during trial between 2001 and 2003. Prosecutors said he also used a device known as a penis pump during at least four trials in the same period. Thompson, 59, was convicted last month of four felony courts of indecent exposure for incidents that took place in his Creek County courtroom.