Plant-growth laminated film and plant-growth illumination apparatus
Provided are a plant-growth laminated film and a plant-growth illumination apparatus that more efficiently provide circularly polarized light used for plant growth. Included are a reflective-type linearly polarizing plate that transmits one of linearly polarized light components of incident light and that reflects the other linearly polarized light component, and a λ/4 plate that converts, into circularly polarized light, linearly polarized light provided by transmission through the reflective-type linearly polarizing plate, wherein the λ/4 plate has an in-plane retardation of 165±40 nm at a wavelength of 660 nm.
1. A plant-growth laminated film comprising:
a reflective-type linearly polarizing plate; and
a λ/4 plate that converts, into circularly polarized light, linearly polarized light provided by transmission through the reflective-type linearly polarizing plate,
wherein the λ/4 plate has an in-plane retardation of 165±40 nm at a wavelength of 660 nm.
2. The plant-growth laminated film according to claim 1 , wherein the λ/4 plate has normal-wavelength-dispersion dependence.
3. The plant-growth laminated film according to claim 1 , wherein the reflective-type linearly polarizing plate has a higher reflection efficiency at a wavelength of 660 nm than at a wavelength of 450 nm.
4. The plant-growth laminated film according to claim 2 , wherein the reflective-type linearly polarizing plate has a higher reflection efficiency at a wavelength of 660 nm than at a wavelength of 450 nm.
5. A plant-growth illumination apparatus comprising:
the plant-growth laminated film according to claim 1 ; and
a light-emitting light source.
6. A plant-growth illumination apparatus comprising:
the plant-growth laminated film according to claim 4 ; and
a light-emitting light source.
7. The plant-growth illumination apparatus according to claim 5 , wherein, in emitted light from the plant-growth illumination apparatus, a degree of circular polarization at a wavelength of 450 nm is lower than a degree of circular polarization at a wavelength of 660 nm.
8. The plant-growth illumination apparatus according to claim 6 , wherein, in emitted light from the plant-growth illumination apparatus, a degree of circular polarization at a wavelength of 450 nm is lower than a degree of circular polarization at a wavelength of 660 nm.