Reflective material

In the UK cyclists must have a white front light and red rear light to cycle at night. This is required by law. However, these lights are often not sufficient, and so it's advisable to wear clothing with reflective strips on them.

But how does reflective technology work? 3M makes a lot of these products using their Scotchlite technology. They use glass beads and prismatic technology to reflect light rays in a way called "retro reflection".

When a ray of light strikes a reflective surface straight on (at a 90 degree angle), the light is reflected straight back along the same path. However, when light hits the surface at an angle, it's reflected at an angle in an opposite direction. Retro-reflectivity occurs when the reflected ray returns in the direction of the light source, regardless of the angle at which it strikes the reflective surface. This reflection can be obtained in one of two ways:

With the use of three mirrors that are perpendicular to each other.



Or with special beads that bend and reflect light rays in a specific way.


Retro-reflective material reflect the largest amount of light of all reflective materials. The strength of reflective light is measured in candela. White material performs at 0.3 candela while retro-reflective material can measure up to 500 candela.