How do reflective objects function?

Question

How do reflective objects, such as street signs or vests, function? How do they work so effectively when light is shined on them in the dark.

Answer 1

It may seem like it's just reflection, but in fact it's several (3?) INTERNAL REFLECTIONS in small spheres (or near-spheres) designed so that the light shone onto them will be returned, on average, in the direction it originally comes from.

This wasn't around until a few decades ago, simply because neither the idea of using successive internal reflections in practical devices, nor the technology to make the precise shapes of the small glass beads, existed yet. The properties of internal reflection had been studied theoretically, long before, but I think the technology to really put the idea into "everyday" practice was probably discovered in the late 1950s. The effect was quite dramatic. The discovery quickly revolutionized both large roadside direction and safety signs, and surface lane indicators on highways, which until then had been the much larger individual "cats' eyes," as they were called, and also quickly led to the large-scale production of reflective sheeting that could be pasted anywhere, like on bicycles, woven into clothing, and incorporated into things like running shoes for dusk or night-time safety. It was an example of a relatively simple scientific, but remarkably effective and practical, life-saving discovery.

Live long and prosper.

Answer 2

In the case of street signs, there are tiny beads of glass mixed with paint.

Most everything is reflective to some degree. This involves light photons bouncing off a surface. The degree of reflectivity depends on the colour and type of surface the light is bouncing off of.

Answer 3

see: http://www.trafficsign.us/signsheet.html

and

http://products3.3m.com/catalog/us/en001/safety/traffic_control/node_H3J9ZPT694be/root_GST1T4S9TCgv/vroot_1PGXVVLN9Xge/gvel_ZWP0QLH92Wgl/theme_us_trafficcontrol_3_0/command_AbcPageHandler/output_html