Powell lens is like a curved roof line with a circular prism. The lens is a laser line generator, which stretches a narrow laser beam into a uniformly illuminated straight line.

Powell prism is a quantum leap wire generator whose performance is better than that of a simple cylindrical lens. The cylindrical lens produces a line of poor illumination, which is limited by a non-uniform, Gaussian laser beam. Powell lens' rounding to the roof is actually generated by spherical aberration redistribution along the light of a large number of complex two-dimensional aspheric curves; reduce the light in the center area, while improving the light level at the end of the line. As a result, very uniform lighting lines are used in all forms of machine vision applications; from biomedical and automotive assembly to the production of chocolate biscuits.

Fan angle
The width of the fan angle of Powell lens is a function of the refractive index of the glass and the angle of the roof. The steeper the roof and the higher the refractive index, the wider the fan angle and the longer the time, the line for a given projection distance. Small fan angle usually uses mild optical glass, n = 1.5, refractive index. The angle of the large fan, preferably made of high refractive index glass, n = 1.8, or higher, to minimize the steeper angle of the roof.

Uniform line

The performance of Powell lens is very sensitive to the characteristics of the incident laser beam and the quality of the aspheric surface of the lens. For demanding applications, uniform illumination of laser lines is best achieved by matching the specific beam characteristics of the Powell lens to the laser module.

The uniformity of Powell lens is not an absolute characteristic, it depends on testing technology. For example, the uniformity measurement will depend on whether a projection line of Powell prism is evaluated in a machine vision application to see a surface by a camera or swept light by a divergent fan detector for laser safety assessment. The difference in uniformity characteristics increases the fan angle, and the divergence difference of Powell lens over 20 degrees becomes significant.