Abstract: A laser apparatus includes a laser oscillator; an acousto-optic modulation unit including a first acousto-optic modulator that diffracts a laser beam from the laser oscillator when a first ultrasonic wave is applied and a second acousto-optic modulator that diffracts a higher order beam output from the first acousto-optic modulator when a second ultrasonic wave is applied; and an amplifier that amplifies the laser beam from the acousto-optic modulation unit, a propagation direction of the first ultrasonic wave relative to a diffracted direction of the higher order beam emitted from the first acousto-optic modulator and a propagation direction of the second ultrasonic wave relative to a diffracted direction of a higher order beam emitted from the second acousto-optic modulator being different.

Abstract: A discharge control valve wherein the inside of a valve casing is partitioned by a pair of horizontal upper and lower partition walls into an upper chamber, an inlet chamber with an inlet port and an outlet chamber with an outlet port in the order named, and a hollow cylindrical valve body is provided which has opened upper and lower ends, penetrates both partition walls and is capable of vertically moving within said three chambers. An upper half portion of said valve body is made a shutter portion and a lower half portion thereof is made a discharge control portion with a number of small holes perforated in its peripheral wall. The height of both portions are made slightly higher than the height of the inlet chamber.