Highly accurate digital holography with a single camera for particle measurement in 3D space

This paper presents a new observation system for digital holography in which the position of the particles distributed in 3D space can be detected with high accuracy. In the present system, two different hologram patterns, generated with two expanded laser lights orthogonally intersecting, are simultaneously recorded on a CCD sensor to convert them to one digital image. The position of small particles in 3D space is measured by identifying each particle between the numerically reconstructed images of particle in near range and those in far range. The particle identification is carried out in the relative space coordinates the origin of which is set using a thin needle. The test results for the particles attached to a glass plate show the higher measurement accuracy of the present system based on digital holography than the conventional one.