Challenges of digital holography in micro-optical measurement

Abstract

Digital holography extends the use of holography with the ability to provide quantitative values of both amplitude and phase information of object. Digital holography has shown to be applicable in a wide variety of applications from metrology to bio imaging. As in traditional holography, a variety of setups are possible in reflection and transmission modes. In transmission digital holography, quantitative phase information of the object can be related to the height variation of a transparent medium with constant refractive index to provide 3-D surface profile of the specimen. In this paper the principles and characteristics of transmission digital holographic microscopy (DHM) are discussed specifically towards microlens measurement. The capability and challenges of DHM for microlens measurement will be tested and shown. This includes image plane measurement such as microlens diameter, pitch in lateral direction, microlens height distribution in axial direction and focal length measurement which is in the range between image plane and hologram plane. Based on experiment results, the capability and challenges of DHM for microlens measurement will be seen and the effort direction for DHM enhancement will be pointed out.