Optical sight having obscured reticle illumination

1. An optical sight, comprising:

an optical train having an input end and an output end, and defining an optical path from the input end to the output end, wherein the optical train has at least one powered optical element, and wherein the optical train includes as an optical element a reticle that comprises:

a reticle substrate,

a reticle relief pattern in the reticle substrate having a relief surface oriented so that the relief surface faces the output end,

a layer of a barrier material that is opaque to visible light deposited upon the relief surface,

a wavelength-converting material within the reticle relief pattern such that the layer of the barrier material lies between the wavelength-converting material and the relief surface of the reticle relief pattern, wherein the wavelength-converting material is excitable by a non-visible excitation wavelength of light to emit a visible wavelength of light, and

a light source of the non-visible excitation wavelength that controllably illuminates the wavelength-converting material, wherein the optical train prevents the non-visible wavelength from propagating out of the input end of the optical train.

2. The optical sight of claim 1 , wherein the optical train includes at least one optically powered lens in addition to the reticle.

3. The optical sight of claim 1 , wherein the optical train includes

an objective,

an image erector, and

an eyepiece.

4. The optical sight of claim 1 , wherein the optical train includes

an objective,

an image erector, and

an eyepiece,

and wherein the reticle lies between the image erector and the eyepiece.

5. The optical sight of claim 1 , wherein the light source is a source of ultraviolet light.

6. The optical sight of claim 1 , wherein the light source is an ultraviolet light emitting diode.

7. The optical sight of claim 1 , further including a housing that encloses the optical train.

8. The optical sight of claim 1 , wherein the wavelength-converting material is a phosphorescent material.

9. The optical sight of claim 1 , wherein the wavelength-converting material is a quantum-dot phosphorescent material.

10. The optical sight of claim 1 , wherein the reticle substrate is made of a material that is transparent to visible light and not transparent to light of the non-visible excitation wavelength.

11. The optical sight of claim 1 , further including

a coating on the reticle substrate, wherein the coating is not transparent to light of the non-visible excitation wavelength.

12. The optical sight of claim 1 , further including

a filter structure disposed to permit light of the non-visible excitation wavelength to reach the wavelength-converting material but not to reach the input end of the optical train, while permitting visible light to enter the input end and pass to the output end.

13. An optical sight, comprising:

an optical train defining an optical path and having at least one optical element, wherein the optical train comprises

an optically powered objective,

an optically powered eyepiece, and

a reticle comprising

a reticle substrate,

a reticle relief pattern in the reticle substrate having a relief surface oriented so that the relief surface faces the output end,

a layer of a barrier material that is opaque to visible light deposited upon the relief surface,

a wavelength-converting material within the reticle relief pattern such that the layer of the barrier material lies between the wavelength-converting material and the relief surface of the reticle relief pattern, wherein the wavelength-converting material is excitable by a non-visible excitation wavelength to emit a visible wavelength of light, and

a light source of the non-visible excitation wavelength that controllably illuminates the wavelength-converting material, wherein the optical train prevents the non-visible wavelength from propagating out of the input end of the optical train; and

a housing that encloses the optical train.