The paper introduces an experimental scheme for measuring the phase of double laser pulses based on the combination of near-field time-stretched dispersion Fourier transform(TS-DFT) and Gerchberg-Saxton(GS) algorithm. The scheme uses dispersive fibers to perform near-field dispersion Fourier transform on the double pulse signal, and then uses the GS algorithm of time domain simulation to complete the phase recovery of the double laser pulses. Finally, the algorithm simulation of this scheme successfully recovered the phase information of the double pulses, which verified the feasibility of the scheme.
Based on femtosecond laser scanning interference, this paper dedicated to the surface profile measurement of silicon wafers. Femtosecond laser has not only low time coherence, but also high spatial coherence and high measurement accuracy. This measurement system is on the basis of a Michelson interferometer. Stepping motor is used to move the measuring arm so as to scan the surface of the measuring object. Then, the reconstruction of the object’s surface profile is accomplished by the algorithm. We use a short-wave infrared camera to record the interference fringes. The surface profile is reconstructed with pixel points, so the pixel size of the camera is the key to the reconstruction. In this paper, a standard part is selected and measured, then the camera pixel is calibrated through the size of the standard part. In this paper, the grating is tested as a standard part, and the camera pixel is calibrated through the grating reticle. Finally, the surface profile of the silicon wafer was measured with the calibrated system.
This paper dedicated to the development of a surface profile measurement system based on the SLD (Super Luminescent Diode) light source for silicon wafer. The silicon wafer is very important as a substrate of semiconductor products such as integrated circuit (IC) chips, light emitting diodes (LEDs), solar cells and MEMS devices [1] . In this paper, Michelson interferometer is used to generate double beams in order to achieve interference. According to the acquired interference fringe image, we obtain the surface profile of the tested silicon wafer. As a light source, SLD has good spatial coherence and due to its higher transmittance to silicon wafers than other wavelength sources, high fringe visibility can be achieved. It can also perform a full scan in a larger step and achieve rapid on-line measurement of the target surface.
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