  We consider the problem of measurement of optical transverse profile
parameters and their conjugate variable. Using multi-mode analysis, we
introduce the concept of detection noise-modes. For Gaussian beams,
displacement and tilt are a pair of transverse profile conjugate variables. We
experimentally demonstrate their optimal encoding and detection with a spatial
homodyning scheme. Using higher order spatial mode squeezing, we show the
sub-shot noise measurements for the displacement and tilt of a Gaussian beam.
