Using the reconstructed real image of the hologram to measure the deep hole ellipticity

A new method combining Abbe image-forming theory with holography was proposed. By recording the frequency spectrum of the object function with small size and primary-aberration-free Fraunhofor holograms, by adjusting the center of the reconstructed zero-order image (which was fixed at the center of the circle to the measured), and by measuring the image's tranverse magnification and its deviations indirectly the ellipticity of the deep hole could be measured. By using the original reference beam as the reconstructing beam and rotating the hologram and the reference beam synchronously, the reconstructed real images could be imaged at various points on the same circumference, which made the measurement more convenient. This device can be used as an endo-imaging system which can measure the ellipticity of a deep hole with a diameter of 50 to 100 centimeters. If a deep hole has a diameter of φP=100m, the focal length of the lens is f=100mm, the measurement precision is about 0.05 mm.