Diffractive optical element and measuring apparatus
A diffractive optical element includes first and second diffractive optical parts to generate diffracted lights two-dimensionally with respect to incident light. The diffracted lights generated by inputting the incident light to the first diffractive optical part are input to the second diffractive optical part in order to generate the diffracted lights from the second diffractive optical part, wherein θ 1 ≧θ 2 and k 1 ≧k 2 stand or, θ 1 ≦θ 2 and k 1 ≦k 2 stand among θ 1 and θ 2 denote diffraction angles of the first and second diffractive optical parts, and k 1 and k 2 denote numbers of light spots of the diffracted lights generated by the first and second diffractive optical parts.
1. A diffractive optical element comprising:
a first diffractive optical part configured to generate diffracted lights two-dimensionally with respect to incident light; and
a second diffractive optical part configured to generate diffracted lights two-dimensionally with respect to incident light;
wherein the diffracted lights generated by inputting the incident light to the first diffractive optical part are input to the second diffractive optical part in order to generate the diffracted lights from the second diffractive optical part, and
wherein θ 1 ≧θ 2 and k 1 ≧k 2 stand or, θ 1 ≦θ 2 and k 1 ≦k 2 stand, where θ 1 denotes a diffraction angle of the first diffractive optical part, k 1 denotes a number of light spots of the diffracted lights generated by the first diffractive optical part, θ 2 denotes a diffraction angle of the second diffractive optical part, and k 2 denotes a number of light spots of the diffracted lights generated by the second diffractive optical part.
2. The diffractive optical element as claimed in claim 1 , wherein
a projection region of the diffractive optical element is formed by overlapping a projection region of the light spots of the diffracted lights generated by the first diffractive optical part with the second diffractive optical part, or
the projection region of the diffractive optical element is formed by overlapping a projection region of the light spots of the diffracted lights generated by the second diffractive optical part with the first diffractive optical part.
3. The diffractive optical element as claimed in claim 1 , wherein at least one of the first diffractive optical part and the second diffractive optical part includes a plurality of basic units that are arranged two-dimensionally.
4. The diffractive optical element as claimed in claim 1 , further comprising:
a first transparent substrate on which the first diffractive optical part is formed; and
a second transparent substrate on which the second diffractive optical part is formed.
5. The diffractive optical element as claimed in claim 4 , wherein the first transparent substrate and the second transparent substrate are bonded together.
6. The diffractive optical element as claimed in claim 1 , further comprising:
a transparent substrate having a first surface on which the first diffractive optical part is formed, and a second surface, opposite to the first surface, on which the second diffractive optical part is formed.
7. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein the diffracted lights are projected on a plane in order to generate a plurality of light spots within a predetermined range on the plane, and
wherein the predetermined range has a rectangular shape and relationships
15
°
≦
θ
d
M
o
/
M
c
>
-
0.02173
θ
d
+
1.314
stand, where M c denotes a number of light spots in a center region amongst N x ×N y or more regions having approximately same shapes and equally dividing the predetermined range, M o denotes an average number of light spots in four corner regions of the predetermined range, θ d denotes a maximum diffraction angle at which the predetermined range is irradiated, and N x and N y are both odd numbers greater than or equal to 3.
8. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein the diffracted lights are projected on a plane in order to generate a plurality of light spots within a predetermined range on the plane, and
wherein the predetermined range has a rectangular shape and relationships
15
°
≦
θ
d
0.8
≦
M
o
/
M
c
≦
1.2
stand, where M c denotes a number of light spots in a center region amongst N x ×N y or more regions having approximately same shapes and equally dividing the predetermined range, M o denotes an average number of light spots in four corner regions of the predetermined range, θ d denotes a maximum diffraction angle at which the predetermined range is irradiated, and N x and N y are both odd numbers greater than or equal to 3.
9. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein the diffracted lights are projected on a plane in order to generate a plurality of light spots within a predetermined range on the plane, and
wherein the predetermined range has a rectangular shape and relationships
15
°
≦
θ
d
M
min
/
M
max
>
-
0.01729
θ
d
+
1.108
stand, where M max denotes a maximum number of light spots in N x ×N y or more regions having approximately same shapes and equally dividing the predetermined range, M min denotes a minimum number of light spots in the N x ×N y or more regions, θ d denotes a maximum diffraction angle at which the predetermined range is irradiated, and N x and N y are both odd numbers greater than or equal to 3.
10. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein the diffracted lights are projected on a plane in order to generate a plurality of light spots within a predetermined range on the plane, and
wherein the predetermined range has a rectangular shape and relationships
30
°
≦
θ
d
0.6
≦
M
min
/
M
max
≦
1.4
stand, where M max denotes a maximum number of light spots in N x ×N y or more regions having approximately same shapes and equally dividing the predetermined range, M min denotes a minimum number of light spots in the N x ×N y or more regions, θ d denotes a maximum diffraction angle at which the predetermined range is irradiated, and N x and N y are both odd numbers greater than or equal to 3.
11. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein the diffracted lights are projected on a plane in order to generate a plurality of light spots within a predetermined range on the plane, and
wherein the predetermined range has a rectangular shape and relationships
15
°
≦
θ
d
0.7
≦
M
min
/
M
max
≦
1.3
stand, where M max denotes a maximum number of light spots in N x ×N y or more regions having approximately same shapes and equally dividing the predetermined range, M min denotes a minimum number of light spots in the N x ×N y or more regions, θ d denotes a maximum diffraction angle at which the predetermined range is irradiated, and N x and N y are both odd numbers greater than or equal to 3.
12. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein the plurality of basic units are formed by performing a Fourier transform or an inverse Fourier transform of a predetermined pattern of the diffracted lights generated by design, and
wherein the predetermined pattern of the diffracted lights generated by design has a light intensity higher in a peripheral region compared to a center region thereof.
13. A diffractive optical element comprising:
a plurality of basic units arranged two-dimensionally, and configured to generate diffracted lights two-dimensionally with respect to incident light,
wherein a plurality of light spots are generated within a predetermined region on a plane by projecting the diffracted lights on the plane, and
wherein the predetermined range has a rectangular shape, N x ×N y or more regions having approximately same shapes and equally dividing the predetermined range include a peripheral region in which the diffracted light has a diffraction angle of 15° or greater, and a light intensity in the peripheral region is 0.4 or greater with respect to a light intensity 1 in a center region of the predetermined range amongst the N x ×N y or more regions.
14. A measuring apparatus comprising:
a light source configured to emit light;
a diffractive optical element recited in any one of claims 1 , 2 , 7 , 8 , 9 , 10 , 11 , 12 and 13 and configured to emit diffracted lights with respect to the light from the light source; and
an imaging device configured to pick up an image of a measuring target that is irradiated with the diffracted lights.