Light deflection device and optical device

A light deflection device comprising:

• a MEMS light deflection element that comprises a reflection plate and a drive mechanism for the reflection plate and drives the reflection plate by the drive mechanism, whereby incident light is one-dimensionally or two-dimensionally deflected by the reflection plate to be emitted;
• and
• an angle increasing optical element that is disposed downstream of the MEMS light deflection element in a light traveling direction and increases an angle range of a deflection angle of the light emitted from the MEMS light deflection element,
• wherein the reflection plate of the MEMS light deflection element has a function of collecting and emitting the incident light,
• the angle increasing optical element includes a diffraction element having different periodic structure pitches in a plane,
• the diffraction element in the angle increasing optical element is a liquid crystal diffraction element,
• the liquid crystal diffraction element includes an optically-anisotropic layer formed of a composition including a liquid crystal compound, the optically-anisotropic layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one direction, and in a case where, in the liquid crystal alignment pattern, a length over which the direction of the optical axis derived from the liquid crystal compound rotates by 180° in the one direction in which the direction of the optical axis derived from the liquid crystal compound changes while continuously rotating is set as a single period, a length of the single period gradually decreases from an inner side toward an outer side, and
• the optically-anisotropic layer has a liquid crystal alignment pattern in a radial shape from an inner side toward an outer side, the liquid crystal alignment pattern being a pattern in which the direction of the optical axis derived from the liquid crystal compound changes while continuously rotating in the one direction.