Tilted-pulse time-resolved off-axis digital holography

Abstract

In this Letter we present an improvement of time-resolved off-axis digital holography by the use of tilted femtosecond laser pulses. The pulse front tilting of the reference beam with respect to the phase front allows larger crossing angles to be used for recording of digital holograms without significant reduction of pulse interference area (typically limited by low temporal coherence of ultrashort pulses). Such approach increases the area of interference fringes, thus enabling the higher resolution of the reconstructed image as well as better separation of dc term. Temporal resolution is not deteriorated by this method, as only the reference pulse is tilted. The proposed technique was applied for direct intensity clamping observations of light filaments in water using the laser pulses of 30 fs duration.

Single-shot off-axis full-field optical coherence tomography

“…Finally, the back-reflected beams from the reference mirror and the sample are combined and directed on a camera (Adimec Q-2HFW, 1440 × 1440 pixels, pitch = 12 μ m, 500 frames/s) using a tube lens ( f′ = 500 mm). The angle between the two beams is again α , thus making it possible to record a full-field off-axis hologram at a given depth 27 . The intensity distribution of the recorded interferogram can be expressed as: where o and r are the complex electric fields of the object and the reference arms, respectively.…”

Optical Measurement of Surface Topography

“…Spectral characteristics of the sample, such as absorption, can determine the wavelength choice. Later, reduced coherence length sources were investigated, for example VCSELs (Mico et al, 2006), femtosecond lasers used with diffractive lenses (Martìnez-Cuenca et al, 2009) or Ti:sapphire lasers (Balciunas et al, 2009) amongst others, in order to minimize the influence of parasitic interference and to decrease their associated noise. Finally, dual-wavelength DHM (see Sect.…”

Synthesis aperture femtosecond-pulsed digital holography

“…14 In order to eliminate the wake interference, the prisms, 15 grating 16,17 or a diffractive lens 18 have been used for interference. The shortness of the ultrashort pulses gives rise to degrading resolution and a limited field of view of the reconstruction images.…”