Guide to the properties and uses of retroreflectors at night.

This publication describes the properties, characteristics and uses of retroreflectors at night and has been written for people who, in one way or another, have to deal with retroreflectors in their professional activity. Sections 2, 3 and 4 introduce the fundamentals of the subject. Explanations regarding the construction and the functioning of the different optical systems of retroreflectors (prismatic, spherical lens retroreflectors) are given in section 5. The effect of dew, fog and frost on retroreflectors is dealt with in section 6 and the deterioration of retroreflectors is discussed in section 7.