Phase modulation device

A phase modulation device comprising:

• an image data generator configured to generate image data corresponding to a distribution of phase change amount or a distribution of phase velocity based on information data;
• a gradation data generator configured to generate gradation data corresponding to each pixel based on the image data;
• and
• a reflective liquid crystal element having a pixel region in which a plurality of pixel electrodes are arranged and a driving voltage of a sawtooth waveform voltage pattern corresponding to the gradation data is applied;
• wherein
• the pixel region comprises:
• a plurality of pixel blocks configured to modulate a phase of incident signal light based on the voltage pattern to change a wavefront of the signal light, and
• a first blank area formed between pixel blocks in a first direction in which the voltage pattern is repeated, and
• in the first blank area, two or more pixel electrodes are arranged in the first direction, and a same driving voltage as the driving voltage applied to a pixel electrode of the pixel block is applied to a pixel electrode adjacent to the pixel electrode of the pixel block.