Movement of an Optical Component in a Bonding Process with UV Curable Adhesive Analyzed by Using Phase-shifting Digital Holography

Movement of an optical component such as a mirror or a beam splitter glued by Ultraviolet (UV) curable adhesive on a metal plate has been investigated by using phase-shifting digital holography. When the optical mirror cube is glued on the metal plate under the illumination of UV-LED light beam, interference fringes produced by the reference wave and the reflected wave from the mirror surface are recorded sequentially as hologram over a period of time and movement of the mirror cube is analyzed from the phase difference of two successive reconstructed complex amplitudes of the reflected waves. The movement of the mirror cube in the hardening process of UV curable adhesive has been followed. It is shown that the movement of the mirror cube can be analyzed by using both the magnitude and the orientation of the vector normal to the displacement of the mirror detected by digital holographic interferometry. Experimental analysis is conducted with a constant UV light intensity. Correlation between the orientation of UV light illumination and the movement of the mirror cube obtained by digital holography is discussed in this paper.