A new technique is proposed to keep a high spatial resolution when using both a reflection moire and using an integrating-bucket phase shifting method. In moire method an image includes high spatial frequency components of the gratings and the second harmonics of them besides moire fringe. These high frequency components cause measurement error when using phase shifting technique. By combining these two methods for a reflection moire we realized to eliminate both the high frequency components of gratings and the second harmonics of them with keeping high-speed measurement. We proved that theory of the new technique and good experimental results.
A moire method using phase shifting technique is proposed for a flatness measurement, with highly accurate and fast measurement time. Two new methods are suggested for the elimination of the reflected light from the back plane of the glass substrate and for the reduction of contour line errors caused by waviness or warp of the sample surface. The former is UV moire technique and the latter is angle error reduction technique. In the UV moire technique a light of the 313nm wavelength is used for generating a moire. The light is able to eliminate the reflection from the back plane of the Liquid Crystal Display (LCD) glass substrate because it is absorbed inside the glass. The angle error reduction technique is to extrapolate data, which are measured in different distance between grating and sample, because the angle error is proportional to the distance between grating and sample. Using these two techniques, the proposed system realizes less than 0.6 microns in accuracy, while the conventional system is more than 10 microns in accuracy.
A moire method using phase shifting technique is proposed for a flatness measurement, with highly accurate and fast measurement time, especially of computer discs, wafers or glass substrates. Two methods are proposed for the expansion of measurement size and for the elimination of the reflected light from the back plane of the glass substrate. One is to joint small measured areas one another the flatness of which are measured in advance and the other is UV moire technique. Using these techniques, the proposed system realizes higher accuracy than conventional techniques without any limitation of the size in the glass substrate measurement.
A new technique is proposed to provide a profile measurement, especially for computer discs, wafers or glass substrates that are highly accurate in flatness. A reflection moire technique using phase shifting method is tried to this flatness measurement. To apply this method to large size samples such as LCD flat panel displays, two trials extension of measurement size and elimination of the reflected light from the back plane of the glass substrate, are developed. One is to combine small areas one after another the flatness of which is measured in advance. The other is using UV wavelength. A wavelength of 313 nm, which is absorbed into the LCD glass substrate, adopted as the light source, and synthetic fused silica lenses are used in optics. It is possible to measure the flatness of the front plane. The technique, which produces much higher accuracy than conventional techniques, can be available in various of optical measurements.