Apparatus and method for illuminating blood

1. An apparatus comprising:

a light-emitting device configured to illuminate a trail of blood from a wounded game animal, the light-emitting device comprising:

a red light source configured to emit red light;

a green light source configured to emit green light;

a first refractive lens configured to direct red light emitted by the red light source to form a red light beam and to direct green light emitted by the green light source to form a green light beam, wherein the red light beam and the green light beam provide a zone of overlapping red and green light outside of the device, the zone of overlapping red and green light when projected onto the blood causing the blood to stand out when following the trail of blood from the wounded game animal; and

an optical adjuster configured to adjust a separation distance between the first refractive lens and at least one of the red light source and the green light source.

2. The apparatus of claim 1 , wherein the optical adjuster is configured to move the first refractive lens with respect to at least one of the red light source and the green light source.

3. The apparatus of claim 2 , wherein the optical adjuster is configured to move the first refractive lens in a direction parallel to an optical axis of the first refractive lens.

4. The apparatus of claim 1 , wherein the optical adjuster is configured to adjust a width of at least one of the red light beam and the green light beam.

5. The apparatus of claim 1 , wherein the optical adjuster is configured to adjust a proximity of the red light beam to the green light beam.

6. The apparatus of claim 1 , wherein a portion of the optical adjuster is rotatable about an optical axis of the first refractive lens.

7. The apparatus of claim 1 , further comprising a reflector configured to reflect a portion of red light emitted by the red light source and a portion of green light emitted by the green light source toward the first refractive lens.

8. The apparatus of claim 1 , further comprising a second lens having an optical axis parallel to an optical axis of the first refractive lens.

9. The apparatus of claim 1 , wherein at least one of the red light source and the green light source comprises a light-emitting surface of a light-emitting diode.

10. The apparatus of claim 1 , wherein red light emitted by the red light source has a peak wavelength between 610 nanometers and 680 nanometers.

11. The apparatus of claim 1 , wherein the center of a light emitting surface of the red light source and the center of a light emitting surface of the green light source are spaced apart a distance of less than 0.125 inches.

12. The apparatus of claim 1 , wherein the first refractive lens has a diopter of between 28 and 40.

13. The apparatus of claim 1 , wherein the first refractive lens has a magnification power of between 7 and 10.

14. The apparatus of claim 1 , wherein the first refractive lens has an optical axis, the first refractive lens being configured to emit a majority of the red light beam and a majority of the green light beam from surface portions of the first refractive lens on radially opposite sides of the optical axis.

15. An apparatus comprising: a light-emitting device configured to illuminate a trail of blood from a wounded game animal, the light-emitting device comprising: a red light source configured to emit a first light beam comprising red light; a green light source configured to emit a second light beam comprising green light; wherein the first light beam and the second light provide a zone of overlapping first and second light beams outside of the device, the zone of overlapping first and second light beams when projected onto blood causing the blood to stand out when following the trail of blood from the wounded game animal, the light-emitting device further comprising a divider positioned between the first and second light sources and operable to maintain separation of the first light beam and the second light beam within the device.

16. A method of illuminating blood, comprising:

providing a light-emitting device configured to illuminate a trail of blood from a wounded game animal, the light-emitting device comprising:

a red light source configured to emit red light;

a green light source configured to emit visible light having a peak wavelength of between 500 and 565 nanometers;

a refractive lens configured to direct red light emitted by the first light source to form a first light beam and to direct visible light emitted by the second light source to form a second light beam;

emitting red light from the first light source and visible light from the second light source to form the first light beam and the second light beam;

moving the light-emitting device such that a portion of the first light beam, a portion of the second light beam, and a zone of overlapping first and second light beams alternately illuminate the trail of blood from the wounded animal, to cause the blood to stand out and allow a hunter to follow the blood trail of the wounded game animal.

17. The method of claim 16 , further comprising adjusting a separation distance between the refractive lens and at least one of the red light source and the green light source.

18. The method of claim 16 , wherein:

red light emitted by the red light source has a peak wavelength between 610 nanometers and 680 nanometers;

visible light emitted by the green light source has a peak wavelength between 500 nanometers and 540 nanometers.

19. The method of claim 16 , wherein the light-emitting device further comprises a reflector having a concave surface to reflect a portion of red light emitted by the red light source and a portion of visible light emitted by the green light source toward the refractive lens.