Characterization of Micro-lenslet Array Using Digital Holographic Interferometric Microscope
When laser light is transmitted through a transparent micro-lenslet array, a phase shift is induced in the transmitted wavefront, depending on the height variation and refractive index of the micro-lenslet array. In this paper, digital holographic interferometric microscope (DHIM) with Fresnel reconstruction method is demonstrated for the characterization of micro-lenslet array. Measurement of diameter (D), sag height (h), radius of curvature (ROC), focal length (f) and shape of micro-lenses are presented in the paper. The height profile of micro-lenses measured by DHIM is compared with commercially available Coherence Correlation Interferometer (CCI) from Taylor Hobson Ltd. UK with axial resolution 0.1 Å. The root mean square error (RSME) between the measurement carried out by DHIM and CCI is 0.12%. The advantage of using the DHIM is that the distortions in the wavefronts due to aberrations in the optical system can be avoided by the interferometric comparison of reconstructed phase with and without the micro-lenslet array.
The financial assistance received from the Defence Research and Development Organization (DRDO), Ministry of Defence, Government of India, under the project entitled ‘Testing of micro optics using digital holographic interferometry’ under FA sanction No. ERIP/ER/1300466/M/01/1556 dated 20 Nov. 2014 is highly acknowledged.
- 1.S. Sinzinger, J. Jahns, Microoptics. Wiley (1999)Google Scholar
- 5.SUS MicroOptics SA, Catalog (2007), pp. 1–20, http://www.amstechnologies.com/fileadmin/amsmedia/downloads/2067_SMO_catalog.pdf
- 6.M. Stedman, K. Lindsey, Limits of surface measurement by stylus instruments, in 1988 International Congress on Optical Science and Engineering (International Society for Optics and Photonics, 1989), pp. 56–61Google Scholar
- 9.B. Xu, Z. Jia, X. Li, Y.L. Chen, Y. Shimizu, S. Ito, W. Gao, Surface form metrology of micro-optics, in International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013) (International Society for Optics and Photonics, 2013), pp. 876902–876902Google Scholar
- 10.J. Aoki, W. Gao, S. Kiyono, T. Ono, A high precision AFM for nanometrology of large area micro-structured surfaces, in Key Engineering Materials, vol. 295. (Trans Tech Publications, 2005), pp. 65–70Google Scholar
- 17.K.J. Weible, R. Volkel, M. Eisner, S. Hoffmann, T. Scharf, H.P. Herzig, Metrology of refractive microlens arrays, in Photonics Europe (International Society for Optics and Photonics, 2004), pp. 43–51Google Scholar
- 27.V. Kebbel, J. Mueller, W.P. Jueptner, Characterization of aspherical micro-optics using digital holography: improvement of accuracy, in International Symposium on Optical Science and Technology (International Society for Optics and Photonics, 2002), pp. 188–197Google Scholar
- 33.U. Schnars, W. Jueptner, Digital Holography: Digital Hologram Recording, Numerical Reconstruction and Related Techniques (Springer, Berlin, Heidelberg, 2005)Google Scholar
- 35.V. Kumar, C. Shakher, Testing of micro-optics using digital holographic interferometric microscopy, in Proceedings of the 4th International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS) (SCITEPRESS—Science and Technology Publications, Lda, 2016), pp. 142–147Google Scholar
- 43.J. Kühn, F. Charrière, T. Colomb, E. Cuche, Y. Emery, C. Depeursinge, Digital holographic microscopy for nanometric quality control of micro-optical components, in Integrated Optoelectronic Devices 2007 (International Society for Optics and Photonics, 2007), pp. 64750V–64750VGoogle Scholar