Laser Precision posted net income for the third quarter of $142,404, a 76% drop from the $584,680 reported a year earlier. Sales for the quarter increased 6%, to $4.9 million from $4.6 million. For the first nine months, the Irvine manufacturer of test and measurement instruments reported net income of $111,094, down 86% from $823,749. Net sales rose 17% in the first nine months of 1986, to $12.7 million from $10.9 million. Gregory A.