Abstract: A miner's cap lamp includes a reflector having a substantially parabolic reflecting surface having a gradient variation from that of a true parabola curve Y.sup.2 =4MX along at least one line towards the outer edge of the reflector, wherein the gradient along the line has a value equal to that of a true parabola at the maximum value of X for the reflector but has a value greater than the gradient of a parabolic surface for a modified region located nearer the pole of the curve, the gradient variation varying continuously over the modified region, such that the gradient variation is a minimum at the maximum value of X of the modified region and the gradient variation is a maximum at the minimum value of X of the modified region.