Liquid crystal optical element and a laser projection apparatus using polymer dispersed liquid crystal

A liquid crystal optical element of a transparent and scattering type for controlling a laser beam having approximately 1 .mu.m of wavelength of interposing a liquid crystal and solidified matrix composite in which nematic liquid crystal is dispersed and held in a solidified matrix between substrate having electrodes at least one of which is transparent, wherein

• the refractive index anisotropy .DELTA.n of the nematic liquid crystal is 0.18 or higher;
• the viscosity .eta.(cSt) thereof is equal to or less than 60;
• the nematic liquid crystal dispersed and held in the solidified matrix is provided with approximately an ellipsoid form;
• a ratio of a first mean diameter R.sub.L in a long axis of said ellipsoid as compared with a second mean diameter R.sub.S in a short axis thereof, or an aspect ratio, L=R.sub.L /R.sub.S, is determined as
• 1. 3.ltoreq.L.ltoreq.2.5,
• a gap d(.mu.m) between electrodes is determined as
• 3.5<.DELTA.n.multidot.d<8.0;
• and
• the refractive index anisotropy .DELTA.n of the liquid crystal the means particle diameter R(.mu.m) of the nematic liquid crystal dispersed and held in the solidified matrix and a number D.sub.1 of liquid crystal per optical unit volume satisfy a relationship of
• 0.8(R.multidot..DELTA.N).sup.-3 <D.sub.1 <1.4(R.multidot..DELTA.n).sup.-3.

A liquid crystal optical element of a transparent and scattering type for controlling a laser beam having approximately 1 .mu.m of wavelength interposing a liquid crystal and solidified matrix composite in which nematic liquid crystal is dispersed and held in a solidified matrix between substrates having electrodes at least one of which is transparent, wherein

• the refractive index anisotropy .DELTA.n of the nematic liquid crystal is 0.18 or higher;
• the viscosity .eta.(cSt) thereof is equal to or less than 60;
• the nematic liquid crystal dispersed and held in the solidified matrix is provided with approximately an ellipsoid form;
• a ratio of a first means diameter R.sub.L in a long axis of said ellipsoid as compared with a second mean diameter R.sub.S in a short axis thereof, or an aspect ratio, L=R.sub.L /R.sub.S, is determined as
• 1. 3`L.ltoreq.2.5,
• the mean diameter value R.sub.M of R.sub.L and R.sub.S is defined as
• R.sub.M =(R.sub.L +R.sub.S)/2,
• the refractive index anisotropy .DELTA.n and said mean diameter value R.sub.M satisfy a first relationship of
• 0.5<.DELTA.n.multidot.R.sub.M <1.3,
• the refractive index .DELTA.n and a gap d(.mu.m) between electrodes satisfy a second relationship of
• 3.5<.DELTA.n.multidot.d<8.0;
• and
• wherein a number D.sub.2 of liquid crystal per optical unit volume satisfy a relationship of
• 0.8(R.sub.M .multidot..DELTA.N).sup.-3 <D.sub.2 <1.4(R.sub.M .multidot..DELTA.n).sup.-3.

A laser projection apparatus comprising:

• a liquid crystal optical element which includes a liquid crystal and solidified matrix composite in which nematic liquid crystal is dispersed and held in a solidified matrix having a refractive index which is substantially equal to an ordinary refractive index (n.sub.O) of the liquid crystal and which is interposed between first and second substrates, wherein the first substrate is provided with at least one segment electrode and the second substrate is provided with at least one common electrode, and wherein at least one of the substrates is transparent;
• a multiplexed driving means for driving the liquid crystal optical element;
• a laser beam source having an output laser beam of approximately 1 .mu.m wavelength;
• a light supply means for transmitting the laser beam to the liquid crystal optical element;
• and
• a reduction type projection optical system for projecting the laser beam from the liquid crystal optical element onto an object with a reduction projection factor N;
• wherein a lead line connected to the at least one common electrode located on the second substrate is partially overlapped with a lead line connected to the at least one segment electrode located on the first substrate, wherein a width W.sub.1 (.mu.m) of the overlapped portion, the reduction reduction factor N, and gap length d(.mu.m) between the at least one common electrode and the at least one segment electrode of the liquid crystal optical element, satisfy a relationship of
• W.sub.1 +d<10.times.N.