Pulsed laser beams include bursts or pulses of light, as implied by name, and have been used for photoalteration of materials, both inorganic and organic alike. Typically, a pulsed laser beam is focused onto a desired area of the material to photoalter the material in this area and, in some instances, the associated peripheral area. Examples of photoalteration of the material include, but are not necessarily limited to, chemical and physical alterations, chemical and physical breakdown, disintegration, ablation, vaporization, or the like.
One example of photoalteration using pulsed laser beams is the photodisruption (e.g., via laser induced optical breakdown) of a material. Localized photodisruptions can be placed at or below the surface of the material to produce high-precision material processing. For example, a micro-optics scanning system may be used to scan the pulsed laser beams to produce an incision in the material and create a flap therefrom. The term “scan” or “scanning” refers to the movement of the focal point of a pulsed laser beam along a desired path. To create a flap of the material, the pulsed laser beam is typically scanned along a pre-determined region (e.g., within the material) in either a spiral pattern or a raster pattern. In general, these patterns are mechanically simple to implement (e.g., continuous) and control for a given scan rate and desired focal point separation of the pulsed laser beam. Additionally, these patterns are generally efficient.
Despite these advantages, the spiral or raster pattern may impose limits on the creation of the flap (e.g., due to mechanical restrictions on the micro-optic based scanning system or the like). In general, faster scan rates are desirable but existing laser scanning equipment may lag commanded laser positions along one axis or both axes and thus, shorten or compress one or more raster scan lines along another axis. For example, a circular scan area using a raster pattern may become elliptical with faster scan rates. In addition, faster scan rates may result in greater accelerations of a mass associated with the scanning system, and these greater accelerations complicate control accuracy. For example, greater accelerations have been observed while scanning of the central region of a spiral pattern (e.g., as the spiral tightens). Greater accelerations have also been observed while scanning the periphery of a raster pattern (e.g., as the scanning changes direction with the raster pattern).
Accordingly, it is desirable to provide a system and method for scanning a pulsed laser beam that improves scanning control. More particularly, it is desirable to provide a system and method for scanning a pulsed laser beam that reduces accelerations during scanning. It is also desirable to provide a system and method for creating a flap with a pulsed laser beam operating at increased pulse repetition rates while maintaining or reducing the acceleration associated with scanning the pulsed laser beam. Additionally, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.