This paper presents a detailed analysis on the influence of misalignment errors of optical components in an orthogonal two-axis Lloyd's mirror interferometer, which can fabricate two-dimensional grating structures in a single exposure. In an ideal condition, defect-free two-dimensional grating structures can be fabricated by the interferometer. However, in a real case, visible stripes caused by misalignment errors of the optical components in the interferometer always appear on the fabricated grating structures. In this paper, theoretical analysis and experiments are carried out to analyze the influences of the misalignment errors of the optical components in the orthogonal two-axis Lloyd's mirror interferometer.

No abstract

No abstract

Three-axis vibration measurement of the linear air-bearing stage demonstrated by utilizing the method of the multi-axis laser interferometer is discussed. In order to detect the X-Y-Z directional vibration of the positioning stage table simultaneously, two-dimensional XY gratings are utilized as the scale grating and the reference grating of the interferometer. The X-and Y-directional positive and negative first-order diffracted beams are superimposed to generate the interference signals on the photodetectors. When the multi-axis vibration is applied to the scale grating, the intensities of the interference signals in X-and Y-directions varied corresponding to the vibration of the scale grating. Consequently, three-axis vibrations of the scale grating can be calculated by processing the X-and Y-directional positive and negative first-order interference signals. In this paper, a three-axis vibrometer based on the grating-interferometer has been developed for measurement of the positioning stage table vibration. The detection method of the vibration based on the Doppler frequency shift has been demonstrated. As an application of the multi-axis grating-interferometric vibrometer, multi-axis vibrations of the linear air-bearing stage are measured by using the developed vibrometer.

This paper presents a design study of an optical configuration for the fabrication of a two-dimensional grating, which will be used as a scale in a planar encoder system. For the modified two-axis Lloyd's mirror interferometer, in which major modifications have been made to the conventional one-axis Lloyd's mirror interferometer, computer simulation is carried out based on wave optics. Three-dimensional light intensity distributions of the fringe patterns are calculated to investigate the effect of the polarization modulation. In addition, a relationship between the asymmetry of the cross-sectional profiles of the grating pattern structures and the designed grating pattern period is also investigated. Furthermore, pattern exposure tests have been carried out by using a prototype optical setup for the modified two-axis Lloyd's mirror interferometer.