Modular polyvinyl chloride retroreflective identification system

1. A multi-layer identification patch, comprising:

a reflective background layer comprising a front side to face away from a garment when the multi-layer identification patch is affixed to the garment; and

a mask layer secured over the front side of the reflective background layer;

wherein the mask layer comprises (a) an opaque layer of flexible polyvinyl chloride (PVC) and (b) a void in the opaque layer of flexible PVC;

wherein the void has a shape that forms an identification symbol; and

wherein the opaque layer of flexible PVC is secured over a first portion of the reflective background layer, thereby fixing the void that forms the identification symbol over a second portion of the reflective background layer, and thereby enabling the second portion of the reflective background layer to reflect light through the void in the shape of the identification symbol.

2. The multi-layer identification patch of claim 1 , wherein the mask layer comprises multiple voids that have respective shapes that form respective identification symbols.

3. The multi-layer identification patch of claim 1 , wherein the mask layer comprises a single monolithic layer of flexible PVC that comprises the void in the shape of the identification symbol.

4. The multi-layer identification patch of claim 3 wherein the mask layer has been heat sealed over the front side of the reflective background layer.

5. The multi-layer identification patch of claim 1 , wherein the reflective background layer comprises a retroreflective material.

6. The multi-layer identification patch of claim 1 , further comprising:

a filter layer between the reflective background layer and the mask layer, wherein the filter layer allows infrared light to pass through the filter layer, and the filter layer prevents visible light from passing through the filter layer.

7. The multi-layer identification patch of claim 1 , further comprising:

an attachment layer secured under the reflective background layer, wherein the attachment layer comprises at least one side of a hook and loop fastener.

8. A multi-layer identification patch, comprising:

a reflective background layer comprising a front side to face away from a garment when the multi-layer identification patch is affixed to the garment; and

a mask layer secured over the front side of the reflective background layer;

wherein the mask layer comprises (a) an opaque layer of flexible polyvinyl chloride (PVC) and (b) a void in the opaque layer of flexible PVC;

wherein the void has a shape that forms an identification symbol;

wherein the opaque layer of flexible PVC is secured over a first portion of the reflective background layer, thereby fixing the void that forms the identification symbol over a second portion of the reflective background layer, and thereby enabling the second portion of the reflective background layer to reflect light through the void in the shape of the identification symbol; and

wherein the multi-layer identification patch further comprises a backing layer secured under the reflective background layer, wherein the backing layer comprises an internal light source, and wherein the reflective background layer allows light from the internal light source to pass through the reflective background layer.

9. The multi-layer identification patch of claim 8 , wherein the internal light source comprises at least one light-emitting diode (LED).

10. The multi-layer identification patch of claim 8 , wherein the internal light source comprises a chemiluminescent material.