A method is performed for scheduling a calibration relating to an optical device in a light source. The method can be performed by a calibration system including a calibration apparatus and a prediction controller. The method includes: receiving a property associated with the optical device while the optical device is being calibrated; calculating a current degradation metric based at least on the optical device property, the degradation metric modeling behavior of the optical device; estimating when a degradation of the optical device would exceed a threshold based on the current degradation metric; and scheduling a calibration of the optical device based at least in part on the estimate of optical device degradation.

An image projection system is provided. The system can be used for performing lithography. The system includes a deuterium light source, a converging lens coupled to the deuterium light source. The system includes an aperture configured to provide image tiling disposed adjacent to the converging lens. The system includes a movable stage disposed adjacent to the aperture. A method of fabricating an optical device is provided. The method includes depositing a resist over a substrate and determining an exposure pattern for the optical device. The method includes exposing a portion of the resist with a light beam based on the determined exposure pattern. Exposing the portion of the resist includes directing the light beam from a deuterium light source to the substrate and developing the resist.

An illumination optical system includes: a mirror part that converges light; a light source part that is disposed at a first focus of the mirror part and emits the light; a first aperture that is disposed at a second focus different from the first focus of the mirror part, absorbs a portion of the light converged at a plane of the second focus, and transmits a first light; a lens part spaced apart from the mirror part with the first aperture interposed between the mirror part and the lens part; a second aperture that is disposed between the first aperture and the lens part, absorbs a portion of the first light, and transmits a second light; and a cooling member that compensates for a temperature of the second aperture.