We claim the ornamental design for a light focusing device, as shown and described.
FIG. 1 is a upper right front perspective view of a light focusing device; dashed lined portions are unclaimed;
FIG. 2 is a left side elevational view of a light focusing device; dashed lined portions are unclaimed; the right side elevational view is identical thereto,
FIG. 3 is a top plan view of a light focusing device;
FIG. 4 is front elevational view of a light focusing device; dashed lined portions are unclaimed;
FIG. 5 is a bottom plan view of a light focusing device, dashed lined portions are unclaimed; and,
FIG. 6 is a rear elevational view of a light focusing device.
The broken lines illustrating portions of the light focusing device form no part of the claimed design.