Bioerodible poly useful as orthopedic implants or vehicles for the sustained delivery of pharmaceutical, cosmetic and agricultural agents from dioxane-based di. A sample-and-hold circuit is coupled to the received RF signal source. Through use of this laser beam machining apparatus, improvement in utilization efficiency of the readout light and improvement in the level of freedom in machining patterns can be expected. The first source driving channel converts the first intermediate code into a first analog voltage according to a first code-to-voltage mapping relation.