| 摘要 |
In the present invention provides, in order to obtain a desired focal depth t in a range alpha of an acceptable increased amount of beam diameter, an exposure head is designed so that the ratio D/W of an output beam width D to a beam width W at the position where a DMD is placed satisfies the following relational formula. <math-cwu id="MATH-US-00001"> <NUMBER>1</NUMBER> <MATH> <MROW> <MFRAC> <MI>D</MI> <MI>W</MI> </MFRAC> <MO>≤</MO> <MFRAC> <MROW> <MFRAC> <MROW> <MI>alpha</MI> <MO>x</MO> <MI>M</MI> </MROW> <MROW> <MN>2</MN> <MO>x</MO> <MI>t</MI> </MROW> </MFRAC> <MO>-</MO> <MFRAC> <MROW> <MI>K</MI> <MO>x</MO> <MI>lambda</MI> </MROW> <MI>a</MI> </MFRAC> </MROW> <MI>theta</MI> </MFRAC> </MROW> </MATH> <mathematica-file id="MATHEMATICA-00001" file="US20030219189A1-20031127-M00001.NB"/> <image id="EMI-M00001" wi="216.027" he="24.97635" file="US20030219189A1-20031127-M00001.TIF" imf="TIFF" ti="MF"/> </MATH-CWU> In the above formula, parameters are defined as follows. lambda: the wavelength of laser light theta: the angle of beam outputted from an illumination light source that is derived by a numerical aperture (NA) of optical fiber according to the following formula theta=sin<-1>(NA) D: the width of beam outputted from the illumination light source W: the beam width at the position where the DMD is placed (at the irradiated surface) a: the size of one pixel on the DMD K: a coefficient determined by beam characteristics, K=1 M: the magnification of imaging optical system t: required focal depth alpha: acceptable increased amount of beam diameter
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