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1 DUV LASER SYSTEM BEAM DIVERGENCE CONTROL APPARATUS AND PROCESS BACKGROUND [0001] Photolithography is a process by which semiconductor circuitry is patterned on a substrate 5 such as a silicon wafer. A photolithography optical source provides deep ultraviolet (DUV) light used to expose a photoresist on the wafer. Often, the optical source is an excimer laser source and the light is a pulsed laser beam. The light beam is passed through a beam delivery unit and a reticle or a mask, and then projected onto a prepared silicon wafer. In this way, a portion of a chip design is patterned into a photoresist that is then developed, etched, and cleaned, then used as a mask for implantation, 10 deposition, etching, and/or other processes on or in the structure of the wafer, and then the process repeats. [0002] For best performance when projecting the light beam onto the prepared wafer, it is often desirable to minimize the divergence of the beam or to keep the divergence of the beam within certain limits. Optical components and/or their mounting and positioning can change with time due to various 15 thermal, mechanical, or chemical effects, which can alter the divergence of the light beam produced by a laser system. Improved beam divergence control processes and apparatuses are subjects of the present disclosure. DETAILED DESCRIPTION 20 [0003] Various aspects and implementations are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. When a particular feature, structure, or characteristic is described in connection with an implementation, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other implementations whether or not explicitly described. 25 [0004] Some features or aspects of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. For example, implementations of the present disclosure may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing 30 device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; cloud-implemented storage, electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be appreciated 35 that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, and so forth. 2 [0005] FIG. 1 shows a photolithography system 100 that includes a light source 102. As described more fully below, the light source 102 produces a pulsed light beam 104 and directs it to a photolithography exposure apparatus 106 that patterns microelectronic and other features on a wafer 110. The wafer 110 is placed on a wafer table 112 constructed to hold the wafer 110 and connected to 5 a positioner 114 configured to accurately position the wafer 110 in accordance with certain parameters. [0006] The pulsed light beam 104 has a wavelength in the DUV range, with a wavelength of 248 nanometers (nm) or 193 nm, for example. The photolithography exposure apparatus 106 includes an optical arrangement 108 having, for example, one or more condenser lenses, a mask, and an objective 10 arrangement. The mask is movable along one or more directions, such as along an optical axis of the pulsed light beam 104 or in a plane that is perpendicular to the opt...