Patent ID: 11959735
Assignee: HITACHI HIGH-TECHNOLOGIES CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 18:
19. A height measuring device, comprising:
a sample stage configured to place an object to be measured;
a drive mechanism for moving the sample stage in a normal line direction of a surface of the object to be measured;
a projection optical system configured to project a light ray onto the object to be measured;
a detection optical system including a detection element configured to detect a reflected light ray from the object to be measured;
a processing device configured to measure a height of the object to be measured based on an output of the detection element;
an adjustment element disposed lengthwise along a projection direction of the light ray projected by the projection optical system and between the projection optical system and the object to be measured, and including a smooth flat light incident surface and a smooth flat light emission surface which are parallel to each other; and
a correction element disposed lengthwise along a direction of the reflected light ray reflected from the object to be measured and between the object to be measured and the detection optical system, and including a smooth flat light incident surface and a smooth flat light emission surface which are parallel to each other, wherein
a length of the adjustment element is longer than a length of the correction element,
the projection optical system includes a switching element configured to switch a trajectory of the light ray with which the object to be measured is irradiated, and the switching element is configured to switch the trajectory of the light ray so as to make a position of an irradiation point of a light ray when the object to be measured is positioned at a first height coincide with a position of an irradiation point of a light ray with respect to the object to be measured when the object to be measured is positioned at a second height different from the first height with the drive mechanism, and
the detection optical system includes a double-sided wedge substrate configured to focus a plurality of trajectories of the light ray into one point on the detection element, the double-sided wedge substrate including a first surface through which a first trajectory of the light ray is transmitted and a second surface, different from the first surface, through which a second trajectory, different from the first trajectory, of the light ray is transmitted.