Hongbo Zhang | Middle Tennessee State University (original) (raw)

Papers by Hongbo Zhang

We proposed a numerical and accurate quadratic phase aberration compensation method in digital ho... more We proposed a numerical and accurate quadratic phase aberration compensation method in digital holography. A phase imitation method based on Gaussian 1σ-criterion is used to obtain the morphological features of the object phase using partial differential, filtering and integration successively. We also propose an adaptive compensation method based on a maximum-minimum-average-α-standard deviation (MMAαSD) evaluation metric to obtain optimal compensated coefficients by minimizing the above metric of the compensation function. The effectiveness and robustness of our method are demonstrated by simulation and experiments.

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

High-precision aspherical cylindrical (acylindrical) lenses are difficult to directly measure bec... more High-precision aspherical cylindrical (acylindrical) lenses are difficult to directly measure because of the phase deviation in the off-axis region. To achieve rapid and non-contact measurement of the acylindrical lens surface, a novel optical structure phase measurement, to the best of our knowledge, is presented in this work. Both common finite-difference and noise-reduction finite-difference methods were used for solving the transport of intensity equation (TIE) for reconstruction of high-resolution surface measurement. The results suggest that both common finite-difference and noise-reduction finite-difference methods can obtain good measurement results. The proposed method allows for the direct measurement of surface information without interference stitching. The accuracy of the TIE measurement has been verified through direct contact measurement.

In this research, we propose the use of end-to-end deep learning simulation approach for assistin... more In this research, we propose the use of end-to-end deep learning simulation approach for assisting the design of LiDAR. The results show that two million points per second rate is optimal for point cloud based intersection classification task. The detection range of up to 100 meters corresponds to optimal classification performance. The 10 degree of upper field of view and 10 degree of lower field of view is sufficient for intersection classification. A linear increase of classification accuracy from 10 to 70 channels is evident. The research bridges the gap of lower level LiDAR simulation and development and self-driving visual tasks and expected to find applications to improve self-driving performance and safety.

We have previously proposed spectral convolutional neural network for digital hologram speckle no... more We have previously proposed spectral convolutional neural network for digital hologram speckle noise reduction. In this report, we show experimentally that it is effective for reducing multiple-levels speckle noise by using only a single hologram.

We propose a lower-cost and practical active scanning optical scanning Fourier ptychographic micr... more We propose a lower-cost and practical active scanning optical scanning Fourier ptychographic microscopy (OSFPM). Featured is a simple setup of Galvo mirrors capable of scanning large-sized objects. The active scanning laser beam is projected onto the sample in a circular pattern to form multiple lower-resolution images. With multiple lower-resolution images, a higher-resolution image is subsequently reconstructed. The OSFPM is able to more precisely control the overlap of the incident light illumination as compared to that in conventional LED-based or other laser-based scanning FPM systems. The proposed microscope is also suitable for applications where a larger size of the object needs to be imaged with efficient illumination.

A novel asymmetric multiple-image encryption method based on quick response code and elliptic cur... more A novel asymmetric multiple-image encryption method based on quick response code and elliptic curve cryptography is proposed through our research. In this new scheme, four quick response code images converted from four images and a random generated intensity key are used as the input for the elliptic curve cryptography image encryption system, which can yield two real number ciphertexts. The ciphertext image is further decrypted through a digital decryption scheme. The proposed system uses both public and private keys thus it is an asymmet-ric encryption system. The method can encrypt up to sixteen images simultaneously. Comprehensive numerical simulations have demonstrated the robustness and effectiveness of the encryption scheme.

High-resolution color Fresnel hologram is computation extensive. In this research, we propose a s... more High-resolution color Fresnel hologram is computation extensive. In this research, we propose a spatial sampling method to reduce the information redundancy of high-resolution Fresnel ho-lograms. The color Fresnel hologram by combining of three monochromatic sampled holograms is achieved without barrier effect. Theoretical analysis of human visual perception of the color Fresnel hologram is conducted. A color holographic 3D display method using RGB LEDs as illumination sources is implemented for color holographic 3D display using color Fresnel holo-grams with the size of 30 mm × 30 mm at the resolution of 94,208 × 94,208 pixels. The proposed method is verified through experimental study illustrating the effectiveness of the proposed method.

Featured Application: The proposed method is applicable for static 3D advertising and holographic... more Featured Application: The proposed method is applicable for static 3D advertising and holographic packaging. Abstract: A fast calculation method for the full parallax high-resolution hologram is proposed based on the elemental light field image (EI) rendering. A 3D object located near the holographic plane is firstly rendered as multiple EIs with a pinhole array. Each EI is interpolated and multiplied by a divergent sphere wave and interfered with a reference wave to form a hogel. Parallel acceleration is used to calculate the high-resolution hologram because calculation of each hogel is independent. A high-resolution hologram with the resolution of 20,0000×20,0000 pixels is calculated only within 8 minutes. Full parallax high-resolution 3D displays are realized by optical reconstructions.

The optical scanning cryptography (OSC) is one of the most utilized optical encryption systems. O... more The optical scanning cryptography (OSC) is one of the most utilized optical encryption systems. Our research is inspired from the observation that there is a linear system property within the ciphertext expression equation of OSC. Given the linear system property, it is feasible to recover the plaintext with cipher-only attack (COA). Our proposed COA method converts the problem of COA into a phase retrieval problem with a single intensity measurement. With the frequency domain constraint and the object domain support obtained from the ciphertext of OSC, the hybrid input-output (HIO) algorithm can be used to recover plaintext. Simulation results demonstrate the feasibility and robustness of the attack. This shows for the first time that the OSC scheme is vulnerable to COA attack.

We propose a full color computer generated holographic near-eye display (NED) based on white ligh... more We propose a full color computer generated holographic near-eye display (NED) based on white light illumination. The method inspired from color rainbow holography is used for calculation of 2D and 3D color holograms. The parameters of the color hologram calculation are designed based on the parameters of the spatial light modulator (SLM) with 4K resolution. A slit type spatial filter is designed in frequency domain to extract red, green and blue frequency components for full color display. A NED system including a white light source, an achromatic collimating lens, a 4K SLM, a 4f optical filtering system, and an achromatic lens as eyepiece is designed and developed. The main contribution of this paper is the first time to apply the rainbow holography concept to the dynamic full color NED with a compact display system. The optical experiments prove the feasibility of the proposed method.

Fringe-pattern profilometry (FPP) has been widely used for phase reconstruction. It involves the ... more Fringe-pattern profilometry (FPP) has been widely used for phase reconstruction. It involves the use of phase shifting for phase retrieval. Phase-shift errors can affect the accuracy of phase reconstruction, and limited studies have been dedicated to studying phase-shift errors due to experimental, human, or environmental factors. We propose a simple and yet accurate phase-shift estimation method. Our study shows that the method is able to accurately estimate the actual phase shifts used in the FPP technique. The proposed method can find its applications in FPP and other phase shifting-based three-dimensional imaging techniques.

International Conference on Optical and Photonic Engineering, 2019

In this research, we systematically investigated the image classification accuracy of Fourier Pty... more In this research, we systematically investigated the image classification accuracy of Fourier Ptychography Microscopy (FPM). Multiple linear regression of image classification accuracy (dependent variable), PSNR and SSIM (independent variables) was performed. Notebly, results show that PSNR, SSIM, and image classification accuracy has a linear relationship. It is therefore feasible to predict the image classification accuracy only based on PSNR and SSIM. It is also found that image classification accuracy of the FPM is not universally significantly differed from the lower resolution image under the higher numerical aperture (NA) condition. The difference is yet much more pronounced under the lower NA condition.

With this study, we propose a method to image the tip crack on transparent materials by using dig... more With this study, we propose a method to image the tip crack on transparent materials by using digital holographic microscopy. More specifically, an optical system based on Mach-Zehnder interference along with an inverted microscopy (Olympus CKX53) was used to image the tip crack of Dammar Varnish transparent material under thermal excitation. A series of holograms were captured and reconstructed for the observation of the changes of the tip crack. The reconstructed holograms were also compared temporally to compute the temporal changes, showing the crack propagation phenomena. Results show that the Dammar Varnish is sensitive to the ambient temperature. Our research demonstrates that digital holographic microscopy is a promising technique for the detection of the fine tip crack and propagation in transparent materials.

Featured Application: The proposed technique has potential for head mounted near-eye VR or AR app... more Featured Application: The proposed technique has potential for head mounted near-eye VR or AR applications. Abstract: A fast computer-generated holographic method with multiple projection images for a near-eye VR (Virtual Reality) and AR (Augmented Reality) 3D display is proposed. A 3D object located near the holographic plane is projected onto a projection plane to obtain a plurality of projected images with different angles. The hologram is calculated by superposition of projected images convolution with corresponding point spread functions (PSF). Holographic 3D display systems with LED as illumination, 4f optical filtering system and lens as eyepiece for near-eye VR display and holographic optical element (HOE) as combiner for near-eye AR display are designed and developed. The results show that the proposed calculation method is about 38 times faster than the conventional point cloud method and the display system is compact and flexible enough to produce speckle noise-free high-quality VR and AR 3D images with efficient focus and defocus capabilities.

In this research, a novel optical multiple-image encryption method based on angular-multiplexing ... more In this research, a novel optical multiple-image encryption method based on angular-multiplexing holography, quick response (QR) code, and spiral phase keys is proposed. With this method, images are transformed into QR codes and subsequently encrypted into a series of encrypted holograms using an angular-multiplexing technique. The encrypted holograms can only be decrypted when the hologram is illuminated with a duplicate of the reference beam and correct fingerprint and spiral phase plate (SPP) keys. The multiplexing performance and key sensitivity of fingerprint and SPP order were both analyzed, showing the high strength of the security of our proposed method.

Earlier research showed that human quiet upright stance posture is intermittently controlled thro... more Earlier research showed that human quiet upright stance posture is intermittently controlled through both open and closed loop control mechanisms. Critical time interval (CTI), the duration describing the time interval between the intermittent control signals is essential to understand the switch frequency of between the open and closed loop control. Yet the value of CTI, in particular the differences between young and older adults remain insufficiently investigated and thus un-clarified. In this research, intermittent critical time interval (ICTI) method was proposed to evaluate the differences of CTI between young and older adults. Consistent to conventional CTI method, it was found that young adults have larger CTI than older adults. The results from the ICTI method have smaller variation and better consistency across participants compared to the conventional CTI method. It is suggested that the higher frequency of intermittent control signals among older adults could be an indicator of lack of confidence or capacity in maintaining quiet upright stance.

An algorithm and MATLAB code for solving nonlinear stochastic rate equations are presented and ap... more An algorithm and MATLAB code for solving nonlinear stochastic rate equations are presented and applied to the problem of parameter optimization using high performance computing. OCIS codes: (000.4430) Numerical approximation and analysis; (270.2500) Fluctuations, relaxations, and noise; (140.3570) Lasers, single-mode. Stochastic modeling is an integral part of nonlinear optics and laser physics with a long and rich history. Examples include modeling of spontaneously initiated processes like Brillouin scattering in optical fiber [1] and first passage times for the startup of a laser [2]. Honeycutt has developed a formal algorithm for implementing a stochastic Runge-Kutta method and has illustrated its application to the ordinary differential equation for the Ornstein-Uhlenbeck process [3]. More recently, we have applied this method to a model for timing jitter of a single-mode, Q-switched, Nd:YAG laser [4]. In this paper, we apply Honeycutt's algorithm to the system of equations used to model the start-up of a single-mode CW Nd:YAG laser with additive white pump noise and shot-to-shot fluctuations in cavity losses, using MATLAB as our computing platform. In addition to this, we employ high-performance computing methods to facilitate parameter optimization for matching simulations to experiments. The rate equations used to model a CW Nd:YAG laser oscillating on a single-mode are given by  

International Conference on Optical and Photonic Engineering, 2019