Co-axis digital holography based on sinusoidal phase modulation using generalized lock-in detection

Abstract

Sinusoidal phase modulating (SPM) interferometers are used to precisely measure complex light fields with simple interferometric setups. Recently, a generalized lock-in technique has been proposed for optimizing the signal extraction in phase-modulated interferometers. This article shows its applicability in digital holography as well as digital holographic interferometry. A compact homemade setup based on the Michelson interferometer was used to observe the scattering sample surface with a spatial resolution of 32 LP/mm; out-of-plane rotation was measured with a theoretical detection limit of 0.004°. The comparison between the generalized lock-in detection and traditional SPM interferometer method was done theoretically and experimentally.

Multi-Array Visible-Light Optical Generalized Spatial Multiplexing–Multiple Input Multiple-Output System with Pearson Coefficient-Based Antenna Selection

“…The MRC-based scheme can achieve near-optimal performance while reducing the complexity of the ML-based SM receiver; however, it does not significantly improve the transmission rate [15]. Accordingly, researchers have proposed an optical generalized spatial modulation (OGSM) algorithm [16][17][18][19][20]. However, the definition of GSM in the current literature is not accurate.…”

Simultaneous 2D in-plane deformation measurement using electronic speckle pattern interferometry with double phase modulations

“…Obviously, when f 1 , f 2 and jf 1 − f 2 j are not equal to each other with a lock-in detection at f 1 , θ 1 ðx; yÞ − θ 3 ðx; yÞ can be extracted; with a lock-in detection at f 2 , θ 2 ðx; yÞ − θ 3 ðx; yÞ can be extracted [9] . The same procedure can be carried out to obtain θ 0 1 ðx; yÞ − θ 0 3 ðx; yÞ and θ 0 2 ðx; yÞ − θ 0 3 ðx; yÞ.…”

“…[10]) or the recently proposed generalized lock-in detection algorithm (see Refs. [9,11,12]), the needed phase information can be obtained. Likewise, while dealing with the same set of data, if we set the demodulation frequency at f 1 in the algorithm, then we can get C 1 ðx; yÞ; if we set it at f 2 , then we can get C 2 ðx; yÞ.…”

“…The micrometer screw advances 10 and 50 μm, respectively, along the Y axis. The generalized lock-in detection [9,11,12] is used to process data. When applying linear/sawtooth phase modulations described by Eqs.…”

“…The micrometer screw advances 50 μm along the Y axis. The lock-in detection [9] is used to process data.…”