DEPOLARIZING ELEMENT, OPTICAL MEASURING DEVICE, AND PROJECTION TYPE DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a depolarizing element which exhibits a spacial distribution of phase differences without separating an incident light and without depending on a polarization state of the incident light for light of a wide wavelength region and acquires high depolarization for the light of the wide wavelength region.SOLUTION: The depolarizing element comprises a first birefringent medium layer and a second birefringent medium layer. Each of the first birefringent medium layer and the second birefringent medium layer has a uniform thickness and includes at least one region of two types of regions respectively having the same phase difference and a different direction of a phase advancing axis in each of depolarizing element planes. A boundary between the two regions included in the first birefringent medium layer and a boundary between the two regions included in the second birefringent medium layer are aligned with each other. A ratio of a phase difference in the first birefringent medium layer and a phase difference in the second birefringent medium layer is 2±0.1:1. An angle between the phase advancing axes in the two types of regions included in the second birefringent medium layer is 45°±4°.