Focusing device comprising a plurality of scatterers and beam scanner and scope device
A focusing device includes a substrate and a plurality of scatterers provided at both sides of the substrate. The scatterers on the both sides of the focusing device may correct geometric aberration, and thus, a field of view (FOV) of the focusing device may be widened.
1. A focusing device comprising:
a substrate;
a first thin lens provided at a first surface of the substrate and comprising a plurality of first scatterers; and
a second thin lens provided at a second surface of the substrate and comprising a plurality of second scatterers,
wherein the first and the second thin lenses are configured so that light incident to the focusing device obliquely to an optical axis of the focusing device can be focused in a focusing point on a focal plane.
2. The focusing device of claim 1 , wherein a phase shift of light that passes through the plurality of second scatterers decreases from a central area of the second thin lens to a peripheral area of the second thin lens.
3. The focusing device of claim 2 , wherein the plurality of second scatterers are configured so that spherical aberration does not occur by the second thin lens.
4. The focusing device of claim 1 , wherein a phase shift of light that passes through the plurality of first scatterers decreases from a peripheral area of the first thin lens to a middle area of the first thin lens and increases from the middle area of the first thin lens to a central area of the first thin lens.
5. The focusing device of claim 1 , wherein the plurality of first scatterers of the first thin lens are configured to correct geometric aberration of the second thin lens.
6. The focusing device of claim 1 , wherein the first and the second thin lenses are configured to change a location of the focusing point according to an angle at which the light is incident on the first surface.
7. The focusing device of claim 6 , wherein the first and the second thin lenses area configured to determine the location of the focusing point according to Equation 1:
h=f* tan θ
wherein ‘h’ is a distance between the location of the focusing point and an optical axis of the focusing device, ‘f’ is an effective focal length of the focusing device, and ‘θ’ is an angle at which the light is incident on the first surface.
8. The focusing device of claim 6 , wherein the first and the second thin lenses area configured to determine the location of the focusing point according to Equation 1:
h=f* sin θ
wherein ‘h’ is a distance between the location of the focusing point and an optical axis of the focusing device, ‘f’ is an effective focal length of the focusing device, and ‘θ’ is an angle at which the light is incident on the first surface.
9. The focusing device of claim 1 , wherein the plurality of first and the plurality of second scatterers are configured to allow incident light within a predetermined wavelength band to form the focusing point on the focal plane.
10. The focusing device of claim 9 , wherein distances between the plurality of first scatterers and distances between the plurality of second scatterers are less than wavelengths in the predetermined wavelength band.
11. The focusing device of claim 9 , wherein respective heights of the plurality of first scatterers and respective heights of the plurality of second scatterers are less than wavelengths in the predetermined wavelength band.
12. The focusing device of claim 9 , further comprising an optical filter configured to block the incident light of wavelengths outside the predetermined wavelength band.
13. The focusing device of claim 1 , wherein at least one of respective shapes of the plurality of first and the plurality of second scatterers and respective sizes of the plurality of first and the plurality of second scatterers changes according to a thickness of the substrate.
14. The focusing device of claim 1 , wherein each of the plurality of first and the plurality of second scatterers has at least one of a cylindrical shape, an cylindroid shape, and a polyhedral pillar shape.