The images you see above were created by a Japanese Institute which utilizes dot-array placement in empty space. In order to make this possible, however, a very high quality laser is necessary which is why this product is not mainstream.
The technicalities on how this works is beyond what many people would understand, and because of a lack of being able to paraphrase the process here is the essentials on how it works:
The emission time of the laser pulse light is approximately a nanosecond (10-9 sec). The device uses one pulse for each dot. The human eye will recognize the after-image effect of plasma emission from displays up to 100 dot/sec. By synchronizing these pulses and controlling them with software, the device can draw any 3D objects in air.
News Source: PhysOrg.com