1. A surface measurement module for 3-D triangulation-based image acquisition of a surface-under-inspection and under observation by at least one camera, the module comprising: (a) a casing housing an optical system comprising a plurality of lens elements positioned between a fixed-pattern optic and a light source; (b) an output of said fixed-pattern optic comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid projected simultaneously, each of the sinusoids represented by the pixels having a unique temporal frequency and each of the pixels projected to satisfy I n p = A p + ∑ k = 1 K B k p cos ( 2 π f k y p + 2 π kn N ) Eq. ( 1.1 ) where I n p is the intensity of a pixel in the projector for the n th projected image in a particular moment in time; K is an integer representing the number of component sinusoids, each component sinusoid having a distinct temporal frequency, where K is less than or equal to (N+1)/2; the parameter B k p represents constants that determine the amplitude or signal strength of the component sinusoids; A p is a scalar; f k is the spatial frequency of the k th sinusoid corresponding to temporal frequency k; and y p represents a spatial coordinate in the projected image; (c) a shifting element to spatially shift said output of said fixed-pattern optic during projection onto the surface-under-inspection; and (d) a plurality of images captured of said output of said fixed-pattern optic during projection onto the surface-under-inspection are used for the image acquisition.