Citizen's real-time LCD hologram.
In March 1991 Holography News[R] reported that the Citizen Watch Company had made a real-time hologram using a liquid crystal device (LCTV) as a spatial light modulator (SL<). This work, conducted at its Saitama technical lab, had used a twisted nematic type of LCD with a diagonal size of just under an inch and 648 x 240 pixels. In the experiment they made an in-line hologram and a reflection hologram of resolution charts and a glass sculpture of a dog, but instead of recording the hologram on a photo-sensitive material the hologram interference pattern falls on to a CCD camera, which in turn converts it in to a video signal which is transmitted to the LCD. To reconstruct the hologram the beam from a HeNe laser passes through the LCTV (or SLM), which modulates it before it then passes through a Fourier transformation lens so that when it falls on to a ground glass screen or viewing mask the image is formed. The response time between frames is 60 micro-seconds.
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