In the verification test based on the setup shown in Fig 1b, a 10 m W laser diode of wavelength 650 nm was used
for illumination, and an optomechanical xyz translator with 0.01 mm resolution applied to actuate the ground glass. Fig. 2 shows a picture record of the high contrast speckle wavefronts developed in front of the optical mouse.The lenses used for recording and illumination (disabled) in the optical mouse are denoted by A and B, respectively. The optical mouse was found to respond to movements of the ground glass in the x and y but not in the z direction. Fig. 3 presents a typical plot of optical mouse translation registered against optomechanical translator movements introduced in the x direction. Identical trends were obtained in the y direction. The optical mouse to ground glass separation used was 300 mm. The measurements were reasonably linear (R2 = 0.988) and the resolution was 0.025 mm. This resolution appears higher than that obtained previously (0.0635 mm) and may be attributed to the higher degree of contrast in the record of speckle
wavefronts as opposed to through oblique illumination of surfaces using LEDs. Occasional drifting was an artifact
that was observed in the experiments. This is likely attributed to electronic noise in the CMOS sensor of the optical
mouse used.