Light conversion member and lighting device including the same
A light conversion member includes a surface of incidence which includes a recessed portion and on which a laser beam is incident and an output surface in which a wavelength of the laser beam is converted and the laser beam having the converted wavelength is output. The recessed portion has a shape corresponding to a wave front shape of the laser beam.
1. A light conversion member comprising:
a surface of incidence which includes a recessed portion on which a laser beam is incident; and
an output surface in which a wavelength of the laser beam is converted and the laser beam having the converted wavelength is output,
wherein the recessed portion has a shape corresponding to a Gaussian mode of the laser beam.
2. The light conversion member of claim 1 , wherein the shape of the recessed portion is formed differently according to a distance between a light source configured to radiate the laser beam and the light conversion member.
3. The light conversion member of claim 1 , wherein the shape of the recessed portion has a determined by function for calculating a radius of curvature according to a distance of Gaussian beam.
4. The light conversion member of claim 1 , wherein the shape of the recessed portion satisfies a radius of curvature function (R(α TEM )) of Equation 1 as follows:
R
(
α
TEM
)
=
R
(
z
)
α
TEM
[
Equation
1
]
wherein α TEM is a constant which determines the radius of curvature of recessed portion, and R(z) is a radius of curvature function of a Gaussian beam of the following Equation 2,
R
(
z
)
=
z
[
1
+
(
πω
0
2
λ
z
)
2
]
[
Equation
2
]
wherein z is the distance between the light source configured to radiate the laser beam and the light conversion member, λ is a wavelength of the laser beam, and ω 0 is a spot size in a beam waist of the laser beam.
5. The light conversion member of claim 1 , wherein the recessed portion includes at least one concave portion or convex portion.
6. The light conversion member of claim 5 , wherein a number of the at least one concave portion or convex portion formed at the recessed portion is varied according to a transverse mode of the laser beam.
7. The light conversion member of claim 1 , wherein the light conversion member includes at least one of a phosphor, a remote phosphor and a quantum dot.
8. The light conversion member of claim 1 , wherein an anti-reflection layer is formed on the surface of incidence.
9. A lighting device comprising:
a light source configured to radiate a laser beam;
a light conversion member in which a wavelength of the laser beam incident from the light source is converted and the laser beam having the converted wavelength is output; and
a reflection member configured to reflect light output from the light conversion member and to output the light as an output,
wherein a recessed portion is formed on a surface of incidence of the light conversion member,
wherein a shape of the recessed portion is formed to correspond to a Gaussian mode of the laser beam.
10. The lighting device of claim 9 , wherein the shape of the recessed portion is formed differently according to a distance between the light source and the light conversion member.
11. The light device of claim 9 , wherein the shape of the recessed portion is determined by a function for calculating a radius of curvature according to a distance of a Gaussian beam.