Speckle reduction of reconstructions of digital holograms using three dimensional filtering

Maycock, Jonathan; McDonald, John; Hennelly, Bryan M.

doi:10.1016/j.optcom.2013.02.062

Cited by 8 publications

(4 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where z is the propagation distance between hologram plane and image plane, M and D x are pixel count and pixel pitch respectively of the image sensor along x-axis, and λ represents source wavelength. The wavefront of the object recorded in digital hologram is computed using a numerical reconstruction algorithm based on the Fresnel approximation of Huygens-Fresnel principle expressed as [27,28] represent the complex amplitude distributions at the object plane and the hologram plane respectively, FT represents the Fourier transform, and =j 1 . In this reconstruction method, resolution of reconstructed image changes with variation in propagation distance.…”

Section: Recording a Digital Hologrammentioning

confidence: 99%

Effect of displacement in object plane on reconstructed image in lens-based digital holography

2021

View full text Add to dashboard Cite

Optical properties of lenses play significant role in digital holographic setups to increase their applications in several fields of imaging and non-destructive testing. In present work, we investigate the effect of introduction of lenses on quality of reconstructed images when they are placed between the object and the image sensor in digital holography. We define a range of propagation distance suitable for recording digital holograms using different off-axis digital holographic setups. The reconstruction results of conventional off-axis digital holographic setup are taken as reference to compare them with lens-based digital holographic setups. Three different digital holographic setups are realised using lenses i.e. concave lens-based setup, convex lens-based setup, and combined concave and convex lenses-based setup. The quality of the reconstructed image is measured by calculating their structural similarity index measure (SSIM) values. These values compare the reconstructed image obtained in the experiment with a reference image of the object obtained through its computer generated hologram (CGH). Performance of these digital holographic setups is compared on the basis of SSIM values of reconstructed images calculated for different separation between object to sensor. On the basis of SSIM values, a range of distances suitable for recording digital holograms for each setup is obtained as 220 mm to 400 mm for the concave lens-based setup, 560 mm to 800 mm for convex lens-based setup, and 220 mm to 600 mm for the concave-convex lens-based setup using concave lens of 50 mm focal length and a convex lens of 80 mm focal length in the experiments.

show abstract

Section: Recording a Digital Hologrammentioning

confidence: 99%

Effect of displacement in object plane on reconstructed image in lens-based digital holography

2021

View full text Add to dashboard Cite

show abstract

“…The reduction of speckle is a very important issue that affects the security strength of the system as mentioned above. Optical and digital techniques for speckle reduction [10,11] should be integrated with the secure sensing system.…”

Section: Current and Future Challengesmentioning

confidence: 99%

Roadmap on optical security

Javidi

Carnicer

Yamaguchi

et al. 2016

J. Opt.

390

125

View full text Add to dashboard Cite

show abstract

“…Approaches include mean and median filtering, Fourier filtering, wavelets 83 or more advanced approaches consisting of filters applied on the 3D intensity volume generated from a single hologram. 84…”

Section: Speckle Noise Mitigationmentioning

confidence: 99%

Compressed digital holography: from micro towards macro

et al. 2016

View full text Add to dashboard Cite

The age of computational imaging is merging the physical hardware-driven approach of photonics with advanced signal processing methods from software-driven computer engineering and applied mathematics. The compressed sensing theory in particular established a practical framework for reconstructing the scene content using few linear combinations of complex measurements and a sparse prior for regularizing the solution. Compressed sensing found direct applications in digital holography for microscopy. Indeed, the wave propagation phenomenon in free space mixes in a natural way the spatial distribution of point sources from the 3-dimensional scene. As the 3-dimensional scene is mapped to a 2-dimensional hologram, the hologram samples form a compressed representation of the scene as well. This overview paper discusses contributions in the field of compressed digital holography at the micro scale. Then, an outreach on future extensions towards the real-size macro scale is discussed. Thanks to advances in sensor technologies, increasing computing power and the recent improvements in sparse digital signal processing, holographic modalities are on the verge of practical high-quality visualization at a macroscopic scale where much higher resolution holograms must be acquired and processed on the computer.

show abstract

Speckle reduction of reconstructions of digital holograms using three dimensional filtering

Cited by 8 publications

References 40 publications

Effect of displacement in object plane on reconstructed image in lens-based digital holography

Effect of displacement in object plane on reconstructed image in lens-based digital holography

Roadmap on optical security

Compressed digital holography: from micro towards macro

Contact Info

Product

Resources

About