We propose a holographic three-dimensional (3-D) printer that produces 3-D hard copies of computer data. A new technique for synthesizing a holographic stereogram (HS) has been invented for the purpose of making accurate hard copies of 3-D objects. The flat-format, Lippmann-type HS is printed by one optical step and is ideally suitable for 3-D printer application. This type of HS has both horizontal and vertical parallaxes so that the reconstructed image is free from distortion. The principle and the image quality of this type of HS are described, and a reconstructed image from this type of HS with 160 × 128 elements is experimentally demonstrated. The systematic constitution of a holographic 3-D printer is also discussed.

Holographic three-dimensional printer: new method

This paper proposes a holographic printer, which produces 3-D hard copies of
computer processed objects. For the purpose of automatic making of 3-D hard copies
of distortion free, a new method to synthesize holographic stereogram is proposed.
It is is flat format and lippmann type holographic stereogram which can be printed
by one optical step. The proposed hologram has not only horizontal parallax but
vertical parallax, so that the reconstructed image is completely free from distortions.
Though a basic experiment, a holographic stereogram of 8.Ox6.4cm2 was
synthesized and a 3-D image is correctly reconstructed. In this paper the principle
and the method of the new technique are described, and the system constitution' and
the problems with the holographic 3-D printer are also discussed.

Holographic 3-D Printer

A two-step holographic process is introduced to fabricate a cylindrical multiplex hologram as an image-plane hologram. By adoption of the achromatic angle in the process the hologram is capable of generating an achromatic image. The most important factors, the location as well as the width of the viewing slits, that affect the quality of the observed image are analyzed and discussed. The change of aspect ratio for the observed image as a function of the viewing distance is theoretically and numerically analyzed. This method can not only eliminate the annoying picket-fence effect but can also increase the vertical viewing range for the observer. Computer simulations as well as experimental results are provided.

Image-plane cylindrical holographic stereogram.

A theory for making a disk-type multiplex hologram is derived. This theory relates the final image point, as seen by the observer, to a point on the original three-dimensional object through a set of equations. From these equations the distortion of the image and the wavelength as seen by each individual eye can be evaluated. Computer simulation shows the characteristics of this hologram. Some experimental results also confirm these characteristics. By reversing the process and specifying a desired image, we generated a set of distorted two-dimensional originals. The hologram fabricated with these distorted images can generate nearly distortion-free images.

Y. Minami

Papers

Multiplex holograms of a skull made of CT images