Four-degree-of-freedom laser pointing control system and control method thereof

Abstract

The invention discloses a four-degree-of-freedom laser pointing control system and a control method thereof. The system comprises a CO2 laser, a direction adjusting module, a light splitting module, a pointing position monitoring module and an industrial personal computer; the CO2 laser is used for emitting a laser beam; the direction adjusting module comprises a first piezoelectric ceramic deflection mirror and a second piezoelectric ceramic deflection mirror and is used for adjusting the direction of the laser beam; the light splitting module is used for splitting the laser beam into a first light beam and a second light beam; the first light beam bombards a tin target; the second light beam is transmitted to the pointing position monitoring module; the pointing position monitoring module comprises a first camera and a second camera which are used for respectively measuring a near-field light spot position and a far-field light spot position of laser pointing; and the industrial personal computer is used for resolving a driving signal applied to the pointing direction adjusting module according to the deviation between the positions of the light spots in the first camera and the second camera and a preset position so as to adjust the horizontal and pitching angles of the first piezoelectric ceramic deflection mirror and the second piezoelectric ceramic deflection mirror in real time. In this way, stable collimation control over laser pointing can be achieved, and the jitter condition of light beams is remarkably reduced.

Description

technical field [0001] The invention relates to the field of laser technology, in particular to a four-degree-of-freedom laser pointing control system and a control method thereof. Background technique [0002] The emergence of extreme ultraviolet (EUV) lithography technology has injected new vitality into the semiconductor industry, which is expected to promote its continued rapid development and enable the continuation of Moore's Law. According to the current research, using high-power narrow pulse width and high repetition frequency CO 2 Laser bombardment of tin targets is the best way to obtain high-quality EUV, that is, laser-induced plasma (Laser Produced Plasma, LPP) technology. To obtain high-quality EUV light, it is necessary to continuously bombard the droplet tin target with a high-precision and high-stability laser beam, but thermal drift inside the laser, air turbulence and temperature gradients, thermal effects in optical components and mirrors, mechanical sup...

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Problems solved by technology

The system is based on multi-variable input and output forms. It needs to measure the optical path distance of each section in the optical path and the focal length of the focusing mirror at the front end of the PSD detector. control precision

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