| 摘要 |
PURPOSE:To solve the problem that the detection precision of the lateral relative position of a first member material and a second member deteriorates caused by the phase shift of an abnormal light by adding a light splitter, a reference-light reflecting surface, a reference- light detector, a cancellation-light emitting device, and a phase control device, all specified. CONSTITUTION:There are provided the followings: a light splitter 54 which divides the light that a light source 50 emits into a detection-light L1 and a reference-light L2; a reference-light reflecting surface 72 which reflects the reference-light L2; a reference-light detector 74 which outputs the intensity signal of the reflected light; cancellation-light emitting devices 80-84 which emit first and second cancellation lights K1, K2, whose wavelengths and intensity are equal to and whose phases are reverse to those af abnormal light and the reflected reference-light both reflected by a transmission-type diffraction grating 24 respectively, to a detection-light detector 64 and the reference-light detector 74; a phase control device 90 which changes the phases of the cancellation lights K1, K2 so that the second cancellation light K2 may cancel the reflected reference-light on the basis of the intensity signal of the reference-light detector 74: and, an actuator 18 which transfers the first part material 10 so that the relative position in the lateral direction of the first part material 10 and the second part material 12 may be a specified one on the basis of the intensity signal of the detection-light detector 64. |
