Noise reduction in dynamic interferometry measurements

Morris, Michael North; Naradikian, Markar; Millerd, James E.

doi:10.1117/12.860450

Cited by 6 publications

(1 citation statement)

References 6 publications

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“…Freischlad [10] et al proposed another extended source that combines rotating ground glass with multimode fibers to suppress coherent noise. Similar configurations had been used by Morris [11] and Kumagai [12]. The use of multimode fiber has been used as a common method to reduce coherent noise and has been used in other areas such as biomedicine and laser display projection [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

An extended light source based on multimode fiber in interferometers

Zhang,

Lu,

Gong

et al. 2023

Optical Metrology and Inspection for Industrial Applications X

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In interferometers, defects on the surface of optical elements can generate coherent noise, such as "Newton's rings," in interferograms, thereby affecting measurement accuracy. To address this issue, this paper proposes a method for extending the light source using a multimode fiber. By adjusting the parallel beam coupling into the multimode fiber, the coherent noise of the light source can be eliminated. The proposed method is verified in a Twyman-Green interferometer with a 25.4 mm diameter, employing a multimode fiber with a core diameter of 1 mm. Experimental results demonstrate a 36.9% reduction in scattering contrast and a 43% improvement in signal-to-noise ratio (SNR) of the interferometer when the fiber is moved ±1 mm perpendicular to the optical axis, while maintaining a fixed incidence angle of 1° to the optical axis. These findings confirm the effectiveness of the proposed method.

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Section: Introductionmentioning

confidence: 99%

An extended light source based on multimode fiber in interferometers

Zhang,

Lu,

Gong

et al. 2023

Optical Metrology and Inspection for Industrial Applications X

View full text Add to dashboard Cite

show abstract

Propagating of partially coherent laser beam in the near-resonant atomic gas

Kong

Wang

Fang

et al. 2017

Optics Communications

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Suppression of Speckle Noise in Digital Holography With Spatial and Temporal Domain Depolarization

Kong

Qian

et al. 2020

IEEE Access

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Speckle noise in digital holography has a great influence on image quality, and one of the reasons for the formation of speckle noise is that the degree of coherence for the reference light and the object light is too high and unnecessary noise is introduced to the recorded hologram. In this paper, the spatial depolarization and the temporal domain depolarization are analyzed to reduce the speckle noise. The spatial depolarization utilizes the depolarization performance of the depolarizer. By adding a quartz depolarizer to the object light, the linearly polarized light in the object light becomes randomly polarized light, thereby reducing the degree of coherence with the reference light, realizing the suppression of speckle noise, and by utilizing the characteristics of pupil parameters towards the depolarization degree, it is to realize the control for the degree of coherence. The temporal domain depolarization uses two quarter-wave plates and adjustable liquid crystal to realize the depolarization superposition. By controlling the phase delay of the liquid crystal phase variable retarder, the multi-depolarization accumulation in a short time is realized, and the experimental results show that this method preserves the detail portion of the image while better removing speckle noise. Finally, the Non-Local Means filtering algorithm is used to make the reconstructed image smoother. The method proposed in this paper has great applicable value for improving the image quality of digital holography system. INDEX TERMS Digital holography speckle noise, depolarization, quartz depolarizer, liquid crystal.

show abstract

Noise reduction in dynamic interferometry measurements

Cited by 6 publications

References 6 publications

An extended light source based on multimode fiber in interferometers

An extended light source based on multimode fiber in interferometers

Propagating of partially coherent laser beam in the near-resonant atomic gas

Suppression of Speckle Noise in Digital Holography With Spatial and Temporal Domain Depolarization

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