Directional glance glass is small bead the material application in traffic facilities
Traffic sign manages in traffic and is main effect in traffic safety. Traffic sign sort is various, but past is to use face of card of common paint spray mostly, nightly indication effect is poorer, prevent traffic accident effectively hard. Now, face of card of foreign traffic sign was used generally already directional glance material. Have the aid of of this kind of mark is shot at car lamp illumination, make the driver is in the hundreds pattern that face of clear shop sign can see go up besides rice, be helpful for safe drive a vehicle greatly. In addition, glance the police uniform, glance segregation is taken, glance guide, glance graticule, glance the establishment such as number plate also is being popularized use. The article only directional glance the fundamental of material, structure and breed make following brief introduction.
One, specular reflection, slow reflex and recursive sex are directional reflection
Arrive from some angle illuminate when a bundle of parallel light when a slick surface, one part light produces reflection namely. Reflex is with normal fiducial, an angle of incidence and an angle of refraction are equal, the fundamental that this is specular reflection (see a picture one) .

Graph one specular reflection pursues 2 diffuse reflection

Arrive from some angle illuminate when a bundle of parallel light when a rough surface, reflection direction of the light is mixed and disorderly, it does not undertake reflexing by reflection law, this is diffuse reflection (see a picture 2)
When a bundle parallel light is in those who have special structure from certain angle illuminate apparently when, quite big one part light shows cone-shaped beam of light to be reflexed to the incident direction of illuminant, and the awl axis of this kind of cone-shaped velocity of light and incident beam of light are parallel. Accordingly, people can see what aurora shines glance around illuminant the surface. This kind of phenomenon calls recursive sex directional reflex, abbreviation is " directional reflex " (see a picture 3) . What we need, reflex function according to this kind namely glance material.

Graph 3 regression sex is directional reflection
2, directional glance the structure of material
Directional glance the main structure of material, it is a kind of glass that counts 10 micron diameter only bead. Because glass and airy refractive index are different, after the light passes Yu Zhu of vitreous bead focusing a bit, if be in focal place to affix,one glances face, OK come out the beam of light that shoots along incident direction reflex. Use what this principle makes to glance film says for " lens glance material " (see a picture 4, graph 5)

Graph 4 overleaf stick reflection face, the light reflexes a graph to incident direction 5 lights pass glass small bead overleaf gets together
Abroad glances of material glance the layer is to use glass commonly small bead silver-gilt, after perhaps doing good appearance covering layer first, aluminium is spent in vacuum, its refractive index is 2.25-2.50, current, homebred glass is small bead because manufacturing facilities and craft standard are wronger, its refractive index has 1.90-2.00 only, and dispersive point of view is old, remain to improve and rise.
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