Illumination with LEDs is of increasing interest in imaging and lithography.In particular,compared to lasers,LEDs are temporally and spatially incoherent,so that speckle effects can be avoided by the application of LE...Illumination with LEDs is of increasing interest in imaging and lithography.In particular,compared to lasers,LEDs are temporally and spatially incoherent,so that speckle effects can be avoided by the application of LEDs.Besides,LED arrays are qualified due to their high optical output power.However,LED arrays have not been widely used for investigating optical effects,e.g.,the Lau effect.In this paper,we propose the application of an LED array for realizing the Lau effect by taking into account the influence of the coherence properties of illumination on the Lau effect.Using spatially incoherent illumination with the LED array or a single LED,triangular distributed Lau fringes can be obtained.We apply the obtained Lau fringes in the optical lithography to produce analog structures.Compared to a single LED,the Lau fringes using the LED array have significantly higher intensities.Hence,the exposure time in the lithography process is largely reduced.展开更多
The effect of the Lau setup illuminated by a partially coherent quasihomogeneous sourceis studied in this paper, thus a new diffraction-interference phenomenon of gratings is yield-ed. An analytic expression is derive...The effect of the Lau setup illuminated by a partially coherent quasihomogeneous sourceis studied in this paper, thus a new diffraction-interference phenomenon of gratings is yield-ed. An analytic expression is derived in terms of the ambiguity function, and numericalsimulations are also given. It is then concluded that the interference fringe distribution canbe interpreted as the superposition of filtered periodic functions by an equivalent windowof coherence in the positions of the grating diffraction orders. The fringe profile varies asthe state of coherence is changed as well as one of the gratings is translated. And they willbecome the Lau fringes and the diffraction intensity distribution of grating at the two extremesof coherence, respectively. Experiments are demonstrated to verify the theory and an appli-cation to interferometry is shown.展开更多
基金the support by the Deutsche Forschungsgemeinschaft(DFG)in the framework of Research Training Group“Tip and laser-based 3D-nanofabrication in extended macroscopic working areas”(GRK 2182/1)at the Technische Universitat Ilmenau,Germany.
文摘Illumination with LEDs is of increasing interest in imaging and lithography.In particular,compared to lasers,LEDs are temporally and spatially incoherent,so that speckle effects can be avoided by the application of LEDs.Besides,LED arrays are qualified due to their high optical output power.However,LED arrays have not been widely used for investigating optical effects,e.g.,the Lau effect.In this paper,we propose the application of an LED array for realizing the Lau effect by taking into account the influence of the coherence properties of illumination on the Lau effect.Using spatially incoherent illumination with the LED array or a single LED,triangular distributed Lau fringes can be obtained.We apply the obtained Lau fringes in the optical lithography to produce analog structures.Compared to a single LED,the Lau fringes using the LED array have significantly higher intensities.Hence,the exposure time in the lithography process is largely reduced.
基金Project supported by the National Natural Science Foundation of China.
文摘The effect of the Lau setup illuminated by a partially coherent quasihomogeneous sourceis studied in this paper, thus a new diffraction-interference phenomenon of gratings is yield-ed. An analytic expression is derived in terms of the ambiguity function, and numericalsimulations are also given. It is then concluded that the interference fringe distribution canbe interpreted as the superposition of filtered periodic functions by an equivalent windowof coherence in the positions of the grating diffraction orders. The fringe profile varies asthe state of coherence is changed as well as one of the gratings is translated. And they willbecome the Lau fringes and the diffraction intensity distribution of grating at the two extremesof coherence, respectively. Experiments are demonstrated to verify the theory and an appli-cation to interferometry is shown.
