| CPC H01L 22/20 (2013.01) [G01B 11/272 (2013.01); G03F 9/7026 (2013.01)] | 34 Claims |

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1. A surface position detection device that obtains position information of a detected surface along an axis that intersects the detected surface, the surface position detection device comprising:
a light transmission unit by which a plurality of detection lights having a smoothly modulated intensity in the detected surface in a first direction within the detected surface are radiated and superimposed onto the detected surface obliquely from a direction having a direction component in the first direction and which forms an irradiation region on the detected surface;
a light reception unit that has a light detection portion having a light reception surface arranged at an optically conjugated position with respect to the detected surface, receives at a different position of the light reception surface, each of the plurality of detection lights reflected by a detection region of which a width in the first direction is a predetermined value in the irradiation region, and outputs each photoelectric conversion signal of the plurality of detection lights; and
a calculation unit that calculates position information of the detected surface based on the photoelectric conversion signal of the plurality of detection lights output from the light reception unit, wherein
each of the plurality of detection lights is caused to (i) have a modulated intensity in the first direction by a sinusoidal function having an identical period and (ii) have a different phase in the first direction of the sinusoidal function from each other in the detected surface, and
the width of the detection region in the first direction is shorter than half of the period of the sinusoidal function.
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