Stripe illuminator based on LED array and parabolic mirror for active triangulation sensors used on mobile robots

This article proposes a new, efficient and cost effective stripe illuminato r for active optical triangulation sensors. The long distance stripe-shaped collimation of the light radiated by a linear LED array is achieved by mea ns of a cylindrical parabolic mirror with a focus line coinciding with the internal reflectors of the LEDs. A computer based design process using a mo del of the LED is presented to find the optimal parabolic shape, radiating aperture and mounting tolerances. A very simple and inexpensive mechanical construction of the light source was realized. Test measurements showed tha t the light source produces a light stripe with an average incidence betwee n 0.6-5.5 mW/cm(2) depending on the range, which enables the detection of o bjects even with very low reflectivity. The width of the light stripe is 6- 10 cm in the 0-2 m range, which allowed a resolution of 5-15 cm using it in a special stripe lighting sensor setup. Test results on an autonomous mobi le robot are briefly presented. The eye safety of the source is also discus sed. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-32 86(00)02810-5].