Optical film, optical element, and imaging device
The present application relates to an optical film, an optical element and an imaging device. The optical film of the present application does not only exhibit broadband polarization conversion characteristics in the visible light region, but also has absorption bands in the visible light region. Such an optical film can be applied to an imaging device such as an augmented reality apparatus as an optical element such as a diffractive light guide plate laminate to suppress crosstalk.
1. An optical film satisfying Equation 1 below, having a half-wave phase retardation characteristic and having an absorption band in the visible light wavelength region:
R (650)/ R (550)> R (450)/ R (550) [Equation 1]
wherein, R (λ) is an in-plane retardation value of the optical film for light having a wavelength of λ nm,
the optical film comprising a first retardation film satisfying Equation 1 and having a quarter-wave phase retardation characteristic, a color filter layer including a dye having an absorption band in the visible light wavelength region, and a second retardation film satisfying Equation 1 and having a quarter-wave phase retardation characteristic.
2. The optical film according to claim 1 , wherein the R(650)/R(550) value of the optical film is 1.01 to 1.19, and the R(450)/R(550) value of the optical film is 0.81 to 0.99.
3. The optical film according to claim 1 , wherein the optical axis of the first retardation film and the optical axis of the second retardation film are parallel to each other.
4. The optical film according to claim 1 , wherein the first retardation film and the second retardation film each comprise a multilayer structure including a first liquid crystal layer having a half-wave phase retardation characteristic and a second liquid crystal layer having a quarter-wave phase retardation characteristic.
5. The optical film according to claim 4 , wherein the second liquid crystal layer is disposed closer to the color filter layer than the first liquid crystal layer.
6. The optical film according to claim 4 , wherein the optical axis of the first liquid crystal layer and the optical axis of the second liquid crystal layer form 55 degrees to 65 degrees from each other.
7. The optical film according to claim 4 , wherein the optical axis of the first liquid crystal layer forms 12.5 degrees to 17.5 degrees and the optical axis of the second liquid crystal layer forms 72.5 degrees to 77.5 degrees, based on the transverse direction or the longitudinal direction of the optical film.
8. The optical film according to claim 1 , wherein the color filter layer is a pressure-sensitive adhesive layer comprising the dye and a pressure-sensitive adhesive resin.
9. The optical film according to claim 1 , further comprising a first base layer and a second base layer on the outer sides of the first retardation film and the second retardation film, respectively.
10. The optical film according to claim 1 , further comprising a first antireflection layer and a second antireflection layer on the outer sides of the first retardation film and the second retardation film, respectively.
11. The optical film according to claim 1 , further comprising a first barrier layer on one side of the first retardation film and a second barrier layer on one side of the second retardation film.
12. An optical element comprising at least two diffractive light guide plates, and the optical film of claim 1 disposed between the at least two diffractive light guide plates.
13. The optical element according to claim 12 , wherein the at least two diffractive light guide plates have different wavelength bands of light to be coupled.
14. The optical element according to claim 12 , wherein the absorption band of the optical film and the wavelength band of the light coupled to the diffractive light guide plate adjacent to the optical film have a region overlapping each other.
15. An imaging device comprising a light source and the optical element of claim 12 disposed on a light outgoing side of the light source.
16. The imaging device according to claim 15 , wherein the imaging device comprises an augmented reality apparatus.