Circular polarizer, and notch filter and band-pass filter comprising same

A notch filter comprising:

• a pair of substrates;
• a polyimide PI layer coated on one surface of each of the pair of the substrates;
• an anti-reflective layer coated on the other surface of each of the pair of the substrates;
• a plurality of first and second spacers disposed to secure a space between the polyimide PI layer;
• a first cholesteric liquid crystal CLC layer which is disposed on the space secured by the first spacer and having right-hand circular polarization characteristics of including a levorotatory chiral material of a predetermined concentration to reflect light of a left-hand circular component of a predetermined frequency band and to transmit light of a right-hand circular component among the light output from a light source;
• and
• a second cholesteric liquid crystal CLC layer which is disposed on the space secured by the second spacer and having left-hand circular polarization characteristics of including a dextrorotatory chiral material of a predetermined concentration to reflect light of a right-hand circular component of a predetermined frequency band and to transmit light of a left-hand circular component among the light output from a light source.

A notch filter comprising:

• a substrate;
• a polyimide PI layer coated on one surface of the substrate;
• a first cholesteric liquid crystal layer CLC spin-coated on the polyimide layer, having right-hand circular polarization characteristics, including a levorotatory chiral material of a predetermined concentration to reflect light of a left-hand circular component of a predetermined frequency band among the light output from a light source;
• and
• a second cholesteric liquid crystal layer CLC spin-coated on the first cholesteric liquid crystal layer, having left-hand circular polarization characteristics and including a dextrorotatory chiral material of a predetermined concentration to reflect light of a left-hand circular component of a predetermined frequency band among light output from a light source.

A bandpass filter comprising:

• a beam splitter for transmitting the light output from a light source;
• and
• a circular polarizer including one of a right-hand circular polarizer including a cholesteric liquid crystal CLC layer including a levorotatory chiral material of a predetermined concentration to reflect light of left-hand circular component of a predetermined frequency band among light passed through the beam splitter, or a left-hand circular polarizer including a cholesteric liquid crystal CLC layer including a dextrorotatory chiral material of a predetermined concentration to reflect light of right-hand circular component of a predetermined frequency band among the light passed through the beam splitter, and
• wherein the beam splitter reflects the light of the left-hand circular component of the predetermined frequency band reflected by the circular polarizer to convert into light of the right-hand circular component, or reflect the light of the right-hand circular component of the predetermined frequency band reflected by the circular polarizer to convert into light of the left-hand circular component.

A filter comprising:

• a plurality of right-hand circular polarizers including a pair of substrates, a polyimide PI layer coated on one surface of each of the pair of the substrates, an anti-reflective AR layer coated on the other surface of each of the pair of the substrates, a plurality of spacers disposed to secure a space between the polyimide PI layer, and a cholesteric liquid crystal CLC layer disposed on the space secured by the spacers and including a levorotary chiral material of a predetermined concentration;
• and
• a plurality of left-hand circular polarizers including a pair of substrates, a polyimide PI layer coated on one surface of each of the pair of the substrates, an anti-reflective AR layer coated on the other surface of each of the pair of the substrates, a plurality of spacers to secure a space between the polyimide PI layers, and a cholesteric liquid crystal CLC layer disposed on the space secured by the spacers and including a dextrorotary chiral material of a predetermined concentration;
• and
• wherein the plurality of right-hand circular polarizers and left-hand circular polarizers are alternately placed at predetermined distances.

A filter comprising:

• a plurality of right-hand circular polarizers including a cholesteric liquid crystal CLC layer including a levorotatory chiral material of a predetermined concentration;
• a plurality of left-hand circular polarizers including a cholesteric liquid crystal CLC layer including a dextrorotatory chiral material of a predetermined concentration;
• and
• an index matching material layer disposed between the plurality of right-hand circular polarizers and the left-hand circular polarizers, and
• wherein the plurality of right-hand circular polarizers and left-hand circular polarizers are placed alternately, and
• wherein the surfaces of the right-hand circular polarizers and the left-hand circular polarizers which are exposed to the outside are anti-reflective coated.