Backlight device and holographic 3-dimensional image display device including the same

A display device comprising:

• a backlight device;
• and
• a light modulator on the backlight device,
• wherein the backlight device comprises:
• a light source configured to emit coherent light in a first direction;
• and
• an optical path difference generator on the light source, the optical path difference generator comprising an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface, and
• wherein the plurality of light emitting surfaces comprises a first light emitting surface and a second light emitting surface that are spaced from each other in the first direction.

A display device comprising:

• a backlight device;
• and
• a light modulator on the backlight device,
• wherein the backlight device comprises:
• a light source configured to emit coherent light;
• and
• an optical path difference generator on the light source, the optical path difference generator comprising an incident surface and a plurality of light emitting surfaces, the light emitting surfaces being parallel to the incident surface and having different separation distances from the incident surface,
• wherein the light source comprises:
• a display panel comprising a plurality of pixels, each of the pixels comprising a light emitting element;
• and
• a first collimator on the display panel, the first collimator comprising a plurality of collimating lenses respectively corresponding to the pixels,
• wherein the optical path difference generator comprises a pattern comprising each of the light emitting surfaces, the pattern being repeatedly arranged, and
• wherein the pattern of the optical path difference generator corresponds to at least one pixel of the plurality of pixels.