scholarly journals Resolution-enhanced OCT and expanded framework of information capacity and resolution in coherent imaging

2021 ◽  
Author(s):  
Nichaluk Leartprapun ◽  
Steven Adie
Keyword(s):  
Optical System ◽  
Noise Suppression ◽  
Ex Vivo ◽  
Signal To Noise Ratio ◽  
Resolution Enhancement ◽  
Collagen Gel ◽  
Free Resolution ◽  
Information Capacity ◽  
Resolution Limit ◽  
Coherent Imaging

Abstract Spatial resolution in optical microscopy has traditionally been treated as a fixed parameter of the optical system. Here, we present an approach to enhance transverse resolution in beam-scanned optical coherence tomography (OCT) beyond its aberration-free resolution limit, without any modification to the optical system. Based on the theorem of invariance of information capacity, resolution-enhanced (RE)-OCT navigates the exchange of information between resolution and signal-to-noise ratio (SNR) by exploiting efficient noise suppression via coherent averaging and a simple computational bandwidth expansion procedure. We demonstrate a resolution enhancement of 1.5× relative to the aberration-free limit while maintaining comparable SNR in silicone phantom. We show that RE-OCT can significantly enhance the visualization of fine microstructural features in collagen gel and ex vivo mouse brain. Beyond RE-OCT, our analysis in the spatial-frequency domain leads to an expanded framework of information capacity and resolution in coherent imaging that contributes new implications to the theory of coherent imaging. RE-OCT can be readily implemented on most OCT systems worldwide, immediately unlocking information that is beyond their current imaging capabilities, and so has the potential for widespread impact in the numerous areas in which OCT is utilized, including the basic sciences and translational medicine.

New Window Function for Very Short Acquisition Times

1998 ◽  
Vol 52 (1) ◽  
pp. 139-142 ◽  
Author(s):  
Lynne R. Spencer ◽  
Daniel D. Traficante
Keyword(s):  
Time Constant ◽  
Time Domain ◽  
Signal To Noise Ratio ◽  
Resolution Enhancement ◽  
Free Resolution ◽  
Window Function ◽  
Data Sets ◽  
Signal To Noise ◽  
Minor Losses ◽  
Better Than

An apodization function, the sinc-TRAF function (S-TRAF), has been developed for application to exponentially decaying data sets where the acquisition times ( AT) is less than or equal to one time constant, T2. For heavily truncated time-domain signals, S-TRAF is able to remove sinc ripple with only minor losses in linewidth (LW) and signal-to-noise ratio (S/N). Ripple removal achieved with the application of S-TRAF rivals that observed from use of the “ultimate ripple-free resolution enhancement” function (URFRE) for AT as low as 0.3 T2*. S-TRAF maintains LW and S/N better than URFRE for all acquisition times examined.

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

Fibrin glue does not improve the fixation of press-fitted cell-free collagen gel plugs in an ex vivo cartilage repair model

2011 ◽  
Vol 20 (2) ◽  
pp. 210-215 ◽  
Author(s):  
Turgay Efe ◽  
Alexander Füglein ◽  
Thomas J. Heyse ◽  
Thomas Stein ◽  
Nina Timmesfeld ◽  
...  
Keyword(s):  
Fibrin Glue ◽  
Cartilage Repair ◽  
Ex Vivo ◽  
Collagen Gel

scholarly journals Rationally Designing Simple Rod-Like Amphiphilic NIR-Emissive AIE Probes for Precise In-Vivo Detection of Aβ Fibrils/Plaques at A Super-Early Stage

2021 ◽  
Author(s):  
Yipu Wang ◽  
Dong Mei ◽  
Xinyi Zhang ◽  
Da-Hui Qu ◽  
Ju Mei ◽  
...  
Keyword(s):  
High Performance ◽  
Ex Vivo ◽  
Early Stage ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
In Vivo Detection ◽  
Different Strains ◽  
Aβ Fibrils

With increase of social aging, Alzheimer's disease (AD) has been one of the serious diseases threatening human health. The occurrence of A<i>β </i>fibrils<i> </i>or plaques is recognized as the hallmark of AD.<i> </i>Currently, optical imaging has stood out to be a promising technique for the imaging of A<i>β</i> fibrils/plaques and the diagnosis of AD. However, restricted by their poor blood-brain barrier (BBB) penetrability, short-wavelength excitation and emission, and aggregation-caused quenching (ACQ) effect, the clinically used gold-standard optical probes such as <a>thioflavin</a> T (ThT) and thioflavin S (ThS), are not effective enough in the early diagnosis of AD <i>in vivo</i>. Herein, we put forward an “all-in-one” design principle and demonstrate its feasibility in developing high-performance fluorescent probes which are specific to A<i>β</i> fibrils/plaques and promising for super-early <i>in</i>-<i>vivo</i> diagnosis of AD. As a proof of concept, a simple rod-like amphiphilic NIR fluorescent AIEgen, i.e., AIE-CNPy-AD, is developed by taking the specificity, BBB penetration ability, deep-tissue penetration capacity, high signal-to-noise ratio (SNR) into consideration. AIE-CNPy-AD is constituted by connecting the electron-donating and accepting moieties through single bonds and tagging with a propanesulfonate tail, giving rise to the NIR fluorescence, aggregation-induced emission (AIE) effect, amphiphilicity, and rod-like structure, which in turn result in high binding-affinity and excellent specificity to A<i>β</i> fibrils/plaques, satisfactory ability to penetrate BBB and deep tissues, ultrahigh SNR and sensitivity, and high-fidelity imaging capability. <i>In-vitro, ex-vivo,</i> and <i>in-vivo</i> <a>identifying of A<i>β</i> fibrils/plaques</a> in different strains of mice indicate that AIE-CNPy-AD holds the universality to the detection of A<i>β</i> fibrils/plaques. It is noteworthy that AIE-CNPy-AD is even able to trace the small and sparsely distributed A<i>β</i> fibrils/plaques in very young AD model mice such as 4-month-old APP/PS1 mice which are reported to be the youngest mice to have A<i>β</i> deposits in brains, suggesting its great potential in diagnosis and intervention of AD at a super-early stage.

scholarly journals Blind Source Separation Based on Quantum Slime Mould Algorithm in Impulse Noise

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Zhiwei Zhang ◽  
Hongyuan Gao ◽  
Jingya Ma ◽  
Shihao Wang ◽  
Helin Sun
Keyword(s):  
Objective Function ◽  
Blind Source Separation ◽  
Impulse Noise ◽  
Noise Suppression ◽  
Signal To Noise Ratio ◽  
Moving Average ◽  
Source Separation ◽  
Hybrid Optimization ◽  
Slime Mould ◽  
Stable Performance

In order to resolve engineering problems that the performance of the traditional blind source separation (BSS) methods deteriorates or even becomes invalid when the unknown source signals are interfered by impulse noise with a low signal-to-noise ratio (SNR), a more effective and robust BSS method is proposed. Based on dual-parameter variable tailing (DPVT) transformation function, moving average filtering (MAF), and median filtering (MF), a filtering system that can achieve noise suppression in an impulse noise environment is proposed, noted as MAF-DPVT-MF. A hybrid optimization objective function is designed based on the two independence criteria to achieve more effective and robust BSS. Meanwhile, combining quantum computation theory with slime mould algorithm (SMA), quantum slime mould algorithm (QSMA) is proposed and QSMA is used to solve the hybrid optimization objective function. The proposed method is called BSS based on QSMA (QSMA-BSS). The simulation results show that QSMA-BSS is superior to the traditional methods. Compared with previous BSS methods, QSMA-BSS has a wider applications range, more stable performance, and higher precision.

Material decomposition for simulated dual-energy breast computed tomography via hybrid optimization method

2020 ◽  
Vol 28 (6) ◽  
pp. 1037-1054
Author(s):  
Temitope E. Komolafe ◽  
Qiang Du ◽  
Yin Zhang ◽  
Zhongyi Wu ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Dictionary Learning ◽  
Breast Tissue ◽  
Noise Suppression ◽  
Signal To Noise Ratio ◽  
Optimization Method ◽  
Dual Energy ◽  
Hybrid Optimization ◽  
Signal To Noise ◽  
Breast Ct ◽  
Different Levels

BACKGROUND: Dual-energy breast CT reconstruction has a potential application that includes separation of microcalcification from healthy breast tissue for assisting early breast cancer detection. OBJECTIVE: To investigate and validate the noise suppression algorithm applied in the decomposition of the simulated breast phantom into microcalcification and healthy breast. METHODS: The proposed hybrid optimization method (HOM) uses a simultaneous algebraic reconstruction technique (SART) output as a prior image, which is then incorporated into the self-adaptive dictionary learning. This self-adaptive dictionary learning seeks each group of patches to faithfully represent the learned dictionary, and the sparsity and non-local similarity of group patches are used to enforce the image regularization term of the prior image. We simulate a numerical phantom by adding different levels of Gaussian noise to test performance of the proposed method. RESULTS: The mean value of peak signal-to-noise ratio (PSNR), structural similarity (SSIM), and root mean square error (RMSE) for the proposed method are (49.043±1.571), (0.997±0.002), (0.003±0.001) and (51.329±1.998), (0.998±0.002), (0.003±0.001) for 35 kVp and 49 kVp, respectively. The PSNR of the proposed method shows greater improvement over TWIST (5.2%), SART (34.6%), FBP (40.4%) and TWIST (3.7%), SART (39.9%), FBP (50.3%) for 35 kVp and 49 kVp energy images, respectively. For the proposed method, the signal-to-noise ratio (SNR) of decomposed normal breast tissue (NBT) is (22.036±1.535), which exceeded that of TWIST, SART, and FBP by 7.5%, 49.6%, and 96.4%, respectively. The results reveal that the proposed algorithm achieves the best performance in both reconstructed and decomposed images under different levels of noise and the performance is due to the high sparsity and good denoising ability of minimization exploited to solve the convex optimization problem. CONCLUSIONS: This study demonstrates the potential of applying dual-energy reconstruction in breast CT to detect and separate clustered MCs from healthy breast tissues without noise amplification. Compared to other competing methods, the proposed algorithm achieves the best noise suppression performance for both reconstructed and decomposed images.

scholarly journals Monte Carlo Investigation of Shot-noise Suppression in Nondegenerate Ballistic and Diffusive Transport Regimes

2000 ◽  
Vol 53 (1) ◽  
pp. 3 ◽  
Author(s):  
L. Reggiani ◽  
A. Reklaitis ◽  
T. González ◽  
J. Mateos ◽  
D. Pardo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Active Region ◽  
Inelastic Scattering ◽  
Shot Noise ◽  
Noise Suppression ◽  
Signal To Noise Ratio ◽  
Diffusive Transport ◽  
Poisson Solver ◽  
Diffusive Regime ◽  
Shot Noise Suppression

We review recent theoretical investigations of shot-noise suppression in nondegenerate semiconductor structures surrounded by two contacts acting as thermal reservoirs. Calculations make use of an ensemble Monte Carlo simulator self-consistently coupled with a one-dimensional Poisson solver. By taking the doping of the injecting contacts and the applied voltage as variable parameters, the influence of elastic and inelastic scattering as well as of tunneling between heterostructures in the active region is investigated. In the case of a homogeneous structure at T = 300 K the transition from ballistic to diffusive transport regimes under different contact injecting statistics is analysed and discussed. Provided significant space-charge effects take place inside the active region, long-range Coulomb interaction is found to play an essential role in suppressing shot noise at applied voltages much higher than the thermal value. In the elastic diffusive regime, momentum space dimensionality is found to modify the suppression factor γ, which within numerical uncertainty takes values respectively of about ⅓, ½ and 0·7 in the 3D, 2D and 1D cases. In the inelastic diffusive regime, shot noise is suppressed to the thermal value. In the case of single and multiple barrier non-resonant heterostructures made by GaAs/AlGaAs at 77 K, the mechanism of suppression is identified in the carrier inhibition to come back to the emitter contact after having been reflected from a barrier. This condition is realised in the presence of strong inelastic scattering associated with emission of optical phonons. At increasing applied voltages for a two-barrier structure, shot noise is suppressed up to about a factor of 0·50 in close analogy with the corresponding resonant barrier-diode. For an increasing number of barriers, shot noise is found to be systematically suppressed to a more significant level by following approximately a 1/(N + 1) behaviour, N being the number of barriers. This mechanism of suppression is expected to conveniently improve the signal-to-noise ratio of these devices.

scholarly journals Lost photon enhances superresolution

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
A. B. Mikhalychev ◽  
P. I. Novik ◽  
I. L. Karuseichyk ◽  
D. A. Lyakhov ◽  
D. L. Michels ◽  
...  
Keyword(s):  
Resolution Enhancement ◽  
Entangled State ◽  
Quantum Imaging ◽  
Coherent Imaging ◽  
Point Spread ◽  
Spread Function ◽  
Diffraction Of Light ◽  
Resolution Limits ◽  
Image Blurring ◽  
Practical Scheme

AbstractQuantum imaging can beat classical resolution limits, imposed by the diffraction of light. In particular, it is known that one can reduce the image blurring and increase the achievable resolution by illuminating an object by entangled light and measuring coincidences of photons. If an n-photon entangled state is used and the nth-order correlation function is measured, the point-spread function (PSF) effectively becomes $$\sqrt{n}$$ n times narrower relatively to classical coherent imaging. Quite surprisingly, measuring n-photon correlations is not the best choice if an n-photon entangled state is available. We show that for measuring (n − 1)-photon coincidences (thus, ignoring one of the available photons), PSF can be made even narrower. This observation paves a way for a strong conditional resolution enhancement by registering one of the photons outside the imaging area. We analyze the conditions necessary for the resolution increase and propose a practical scheme, suitable for observation and exploitation of the effect.

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