STEREOMICROSCOPE PHOTOGRAMMETRY FOR THE MEASUREMENT OF SMALL OBJECTS

A stereoscopic microscope has been used in combination with the body of a 35 mm camera to obtain stereophotographs, at scales up to 6:1, of objects only a few millimetres in size. Subsequent stereocomparator observations have been used to deduce height differences on the objects 10 a precision, for the mean of five sets of readings, of ±0.01 mm for closely spaced points. Using more widely separated points, the precision was estimated to be ± 0.05 mm. Depths were computed using × parallaxes after a number of parameters were fixed by calibration. The large convergence angle of the microscope axes was a crucial parameter; rotations about the camera axis were found to be significant variables.