Digital holographic microscopy allows optical path difference measurement. Optical path difference depends on the both refractive index and morphology of sample. We developed a dual-wavelength in-line digital holographic microscope that can measure simultaneously the refractive index and morphology of a sample, providing highly precise three-dimensional information. Here we propose theoretical and experimental methods for dual-wavelength in-line digital holographic microscopy. The measured data were reasonable, although there was data error. By improving the experimental method, we could measure the refractive index more precisely and obtain more accurate three-dimensional information on samples.

Keywords: Holography, Image reconstruction, Diffractive optics,

OCIS codes: 090.0090; 100.3010; 050.1970

1. E. Cuche, P. Marquet, and C. Depeursinge, "Simultaneous amplitude-contrast and quantitative phase-contrast microscopy by numerical reconstruction of Fresnel off-axis holograms," Appl. Opt. 38, 6994-7001 (1999)
   
2. L. Xu, X. Peng, Z. Guo, J. Miao, and A. Asundi, "Studies of digital microscopic with application to microstructure testing," Appl. Opt. 40, 5046-5051 (2001)
   
3. M. Jeong, N. Kim, and J. H. Park, "Elemental image synthesis for integral imaging using phase-shifting digital holography," J. Opt. Soc. Korea 12, 275-280 (2008)
   
4. M. A. Kronrod, N. S. Merzlyakov, and L. P. Yaroslavski, "Reconstruction of hologram with a computer," Sov. Phys. Tech. 17, 434-444 (1972)
5. L. P. Yaroslavskii and N. S. Merzlyakov, Methods of Digital Holography (Consultants Bureau, New York, USA, 1980)
6. L. Onural and P. D. Scott, "Digital decoding of in-line holograms," Opt. Eng. 26, 1124-1132 (1987)
7. J. W. Goodman, Introduction to Fourier Optics, 2nd ed., edited by J. Goodman (McGraw Hill, New York, USA, 2005), Chapter 9
8. U. Schnars and W. Juepther, Digital Holography, edited by U. Schnars and W. Juepther (Springer, Heidelberg, Germany, 2005)
9. L. Xu, J. Miao, and A. Asundi, "Properties of digital holography based on in-line configuration," Opt. Eng. 39, 3214-3219 (1999)
   
10. C. Depeursinge, Digital Holography and Three-dimensional Display, edited by T. C. Poon (Springer, New York, USA, 2006)
11. D. Kim, B. J. Baek, Y. D. Kim, and B. Javidi, "3D nano object recognition based on phase measurement technique," J. Opt. Soc. Korea 11, 108-112 (2007)
    
12. J. W. Kang and C. K. Hong, "Three dimensional shape measurement of a micro Fresnel lens with in-line phaseshifting digital holographic microscopy," J. Opt. Soc. Korea 10, 178-183 (2006)
13. H. Cho, J. Lim, D. C. Kim, S. Shin, and Y. Yu, "Threedimensional information and two-dimensional refractive index measurements using combined digital holographic microscope," J. Korean Phys. Soc. 53, 2391-2395 (2008)
    
14. J. Kuhn, F. Charrierea, T. Colomba, E. Cuche, Y. Emery, and C. Depeursinge, "Measurements of Corner cubes microstructures by high-magnification digital holographic microscopy," Proc. SPIE 6188, 618804-618814 (2006)
    
15. C. Polhemus, "Two-wavelength interferometry," Appl. Opt. 12, 2071-2074 (1973)
    
16. J. Gass, A. Dako, and M. K. Kim, "Phase imaging without 2 pi ambiguity by multiwavelength digital holography," Opt. Lett. 28, 1141-1143 (2003)
    
17. Y. Fu, G. Pedrini, B. Hennelly, R. Groves, and W. Osten, "Dual-wavelength image-plane digital holography for dynamic measurement," Opt. Laser Technol. 47, 552-557 (2008)
18. K. Creath, Y. Cheng, and J. C. Wyant, "Contouring aspheric surfaces using two-wavelength phase-shifting interferometry," Optica Acta 32, 1455-1464 (1985)
19. P. Ferraro, S. D. Nicola, G. Coppola, A. Finizio, D. Alfieri, and G. Pierattini, "Controlling image size as a function of distance and wavelength in Fresnel-transform reconstruction of digital holograms," Opt. Lett. 29, 844-846 (2004)
    
20. N. Demoli, D. Vukicevic, and M. Torzynski, "Dynamic digital holographic interferometry with three wavelengths," Opt. Exp. 11, 767-774 (2003)