Synthesized femtosecond laser pulse source for two-wavelength contouring with simultaneously recorded digital holograms.
A dual-wavelength femtosecond laser pulse source and its application for digital holographic single-shot contouring are presented. The synthesized laser source combines sub-picosecond time scales with a wide reconstruction range. A center wavelength distance of the two separated pulses of only 15 nm with a high contrast was demonstrated by spectral shaping of the 50 nm broad seed spectrum centered at 800 nm. Owing to the resulting synthetic wavelength, the scan depth range without phase ambiguity is extended to the 100-microm-range. Single-shot dual-wavelength imaging is achieved by using two CMOS cameras in a Twyman-Green interferometer, which is extended by a polarization encoding sequence to separate the holograms. The principle of the method is revealed, and experimental results concerning a single axis scanner mirror operating at a resonance frequency of 0.5 kHz are presented. Within the synthetic wavelength, the phase difference information of the object was unambiguously retrieved and the 3D-shape calculated. To the best of our knowledge, this is the first time that single-shot two-wavelength contouring on a sub-ps time scale is reported.
Hansel
Thomas
T
Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Str. 2a, 12489 Berlin, Germany. hansel@mbi-berlin.de
Steinmeyer
Günter
G
Grunwald
Ruediger
R
Falldorf
Claas
C
Bonitz
Jens
J
Kaufmann
Christian
C
Kebbel
Volker
V
Griebner
Uwe
U
D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006696:Holography / Q000295:instrumentation* / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D016247:Information Storage and Retrieval / Q000379:methods*; D007834:Lasers; D007909:Lenses; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*