Abstract

Digital holography (DH) [1] has become a topic of growing interest which finds its spot in the three dimensional imaging, as well as biomedical imaging and metrology. One practical limitation in DH with a single wavelength light is that it can only handle smooth profiles and step height less than half a wavelength (λ/2). To extend the dynamic range in depth over λ/2, dual-wavelength DH has been proposed [2]. In this method, DH is performed at two different wavelengths (λ₁, λ₂), and then the synthesized wavelength between them λ_1,2 [= (λ₁λ₂) /|λ₁-λ₂|] is used to extend the dynamic range in depth up to λ_1,2. However, since stable CW laser oscillates at only a few discrete wavelengths, such as 532 nm, 633 nm, or 780 nm, it is difficult to obtain an arbitrary λ_1,2.

© 2016 Japan Society of Applied Physics, Optical Society of America