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High resolution and fast dynamic visualization in 3D can be achieved by combining light sheet and wavefront coding. This results in a system that allows the light sheet to be positioned at different distances from the focus plane. By scanning the light sheet through the sample, it is possible to produce high-resolution volumetric images of living samples at unprecedented speeds.

International audience; Increasing the capture volume of visible cameras while maintaining high image resolutions, low power consumption and standard video-frame rate operation is of utmost importance for hand-free night vision goggles or embedded surveillance systems. Since such imaging systems require to operate at high aperture, their optical design has become more complex and critical. Therefore new design alternatives have to be considered. Among them, wavefront coding changes and desensitizes the modulation transfer function (MTF) of the lens by inserting a phase mask in the vicinity of the aperture stop. This smart filter is combined with an efficient image processing that ensures optimal image quality over a larger depth of field. In this paper recent advances are discussed concerning design and integration of a compact imaging system based on wavefront coding. We address the design, the integration and the characterization of a High Definition (HD) camera of large aperture (F/1.2) operating in the visible and near infrared spectral ranges, endowed with wavefront coding. Two types of phase masks (pyramidal and polynomial) have been jointly optimized with their deconvolution algorithm in order to meet the best performance along an increased range of focus distances and manufactured. Real time deconvolution processing is implemented on a Field Programmable Gate Array. It is shown that despite the high data throughput of an HD imaging chain, the level of power consumption is far below the initial specifications. We have characterized the performances with and without wavefront coding through MTF measurements and image quality assessments. A depth-of- field increase up to x2.5 has been demonstrated in accordance with the theoretical predictions.

A focusing-free and multispectral three-dimensional endoscope based on a compact compound-eye camera is proposed. A prototype TOMBO endoscope with 3 ×2 aspherical lenses using a wavefront coding technique and a 640 ×480-pixel color imager demonstrates extended depth of field and registration of multispectral images based on an estimated depth map. © 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 95(11): 14–27, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11431

The wavefront coding technique is used to enlarge the depth of field (DOF) of incoherent imaging systems.The key to wavefront coding lies in the design of suitable phase masks. To date, numerous kinds of phase masks are proposed. However, further understanding is needed regarding phase mask with its phase function being in a standard sinusoidal form. Therefore, the characteristics of such a phase mask are studied in this letter. Deriving the defocused optical transfer function (OTF) analytically proves that the standard sinusoidal phase mask is effective in extending the DOF, and actual experiments confirm the numerical results. At the same time, with the Fisher information as a criterion, the standard sinusoidal phase mask shows a higher tolerance to focus errors (especially severe focus errors) than the classical cubic phase mask.

Wavefront coding system is a new type of optical-digital two-step imaging system.The cubic phase mask is used to get asymmetric point spread function and the intermediate blurred image which nearly the same in a considerable depth of field.Combined with spatial domain optical imaging modeland kronecker product,an image restoration algorithm which based on the Bi-CGSTAB(BiConjugate Gradient Stabilized) and antireflective boundary conditions was used in the digital decoding part of the wavefront coding system.This algorithm have advantages such as small computing amount,high computing speed and nearly no boundary effect.The new algorithm was optimized and transplanted with the characteristics of parallel computing for the platform of TMS320DM642.The whole platform consists of image capture module,image display module and external memory module.By a specially designed optical system,the experiment imaging the human and object with the object distance of 1 m,5 m and 10 m.From the experimental result of middle blurred images,the effect of this new algorithm on the platform of TMS320DM642 is good,and it gives the possibility to realization of the truly portable and practical of the wavefront coding system.

Certain optical aberrations of imaging systems yield low resolution images. Wavefront coding has proven to minimise this problem by means of hybrid optical-digital imaging systems. The optical part usually involves a phase plate described in terms of cubic polynomials whose shape is a linear combination of ( x 3 + y 3 ) and ( x 2 y + xy 2 ). Optimization is achieved by seeking the most appropriate linear combination with respect to the optical system's constraints. Here, we propose the shape of two pairs of phase plates such that by means of relative rotations they allow for variation of the linear combination of the cubic terms. This will enable adaptive optimization of the cubic phase to the optical system's constraints when these vary in time. Results will be illustrated with numerical simulations.

Wavefront coding is a technique that makes use of aspheric phase masks and image processing to greatly increase the depth of focus and/or reduce the cost of imaging systems. The phase mask adds a controlled amount of aberrations to the optical system in such a way that invariant imaging properties are achieved over a wide range of defocus. When aspheric phase plates are fabricated, their shape has to be carefully designed to avoid introducing other aberrations into the optical system, which could reduce its performance. In this work, we will show how inherent spherical aberration for trefoil-shaped phase plates reduces the quality of color images. Results will be illustrated with numerical simulations. We will show that a fourth-order polynomial added to a trefoil shaped phase mask can avoid the plate generating undesired spherical aberration that will affect the final quality of the decoded color images.

We propose a novel optical design method for small F/number (F/#) compact camera module using wavefront coding. Decreasing the F/# decreases the focus depth of the optical system, which can result in manufacturing tolerances so tight that fabrication is impossible. To obtain reasonable tolerances for easy fabrication and alignment of compact camera module, we designed the final imaging system to have a target wavefront with an extended focus depth. Because additional optical elements, such as phase plates, are not available for compact camera modules, target wavefront should be the combination of the wavefront errors of all lenses in the optical system. Wavefront-coded compact camera modules have higher tolerances and an extended focus depth, so that the images obtained from them have high resolution over a broad defocus range. Images simulated by a wavefront-coded optical system can be restored to much higher resolution using deconvolution of images and a point spread function given by the coded target wavefront.

The analyses of the imaging performance of the wavefront coding system are always based on the Fourier optics. In this paper, geometrical optics is used to analyze the imaging characteristics of arbitrary phase mask in the wavefront coding system. The characteristics of the spot diagrams created by odd and even symmetrical phase masks, including the size, upper and lower boundaries, ray structure, and the stability, are analyzed by the ray aberration theory. These characteristics are also compared with those obtained by Fourier optics, and the two sets of characteristics are proved to be consistent with each other quite well.

We propose the use of two asymmetrical phase masks combined with the subtracted imaging method to enhance the signal-to-noise ratio in wavefront coding systems. This subtracted imaging technique is similar to the variable pinhole diameter in confocal microscopy. Two different phase modulations of same phase masks are employed to promote the magnitude of the optical transfer function (OTF). The ratio factor is used to control the phase variation between two phase masks. The noise of decoded images is suppressed owing to the higher magnitude of the OTF than the wavefront coding systems with a phase mask. A tangent phase mask as an example is used to demonstrate our concept. Simulated results show that the performance promotion controls noise amplification of decoded images while maintaining a depth-of-field extension.

Decoupling the illumination from the detection optics in microscopy can be achieved by combining light sheet and wavefront coding. This results in a system that allows the light sheet to produce optical sections from out of focus planes. By scanning the light sheet through the sample, it is possible to produce high-resolution volumetric images of living samples at unprecedented speeds.

Hybrid optical–digital imaging involves a combination of optical coding during image formation and digital decoding and image reconstruction. This process offers enhanced functionality beyond what is possible using conventional purely optical imaging, for example, in the fields of miniaturization, cost reduction, extended depth of field and three-dimentional imaging. This article focuses on one of the most important hybrid imaging techniques namely, wavefront coding, which was proposed principally as a means to extend the depth of field of an imaging system. A review of the theory behind wavefront coding, the manufacturing of wavefront-coding elements and various applications for which it has been proposed is provided.

In this work we explore the use of the wavefront coding technique for obtaining high resolution images of the retina of human eyes. The numerical analysis pretends to show the robustness of the technique under changes in pupil diameter and wavefront shape including intersubject and intrasubject variability, using always the same restoration filter or image decoder. The results show that it is possible to obtain high resolution images under different ocular aberrations and pupil diameters with the same decoder, opening the possibility of real time high resolution images with this low-cost and robust technique.

By properly designing a phase pupil mask to modulate or encode the optical images and then digitally restoring them, one can greatly extend the depth of field and improve image quality. The original works done by Dowski and Cathey introduce the use of a cubic phase pupil mask to extend the depth of field. The theoretical and experimental researches all verified its effectiveness. In this paper, we suggest the use of an exponential phase pupil mask to extend the depth of field. This phase mask has two variable parameters for designing to control the shape of the mask so as to modulate the wave-front more flexible. We employ an optimization procedure based on the Fisher information metric to obtain the optimum values of the parameters for the exponential and the cubic masks, respectively. A series of performance comparisons between these two optimized phase masks in extending the depth of field are then done. The results show that the exponential phase mask provide slight advantage to the cubic one in several aspects. (c) 2006 Elsevier B.V. All rights reserved.

By applying the wavefront coding technique to an optical system, the depth of focus can be greatly increased. Several complicated methods, such as Fisher Information on based method, have already been taken to optimize for the best pupil phase mask in ideal condition. Here one simple point spread function (PSF) based method with only the standard deviation method used to evaluate the PSF stability over the depth of focus is taken to optimize for the best coefficients of pupil phase mask in practical optical systems. Results of imaging simulations for optical systems with and without pupil phase mask are presented, and the sharpness of image is calculated for comparison. The optimized results showed better and much more stable imaging quality over the original system without changing the position of the image plane.

Iris recognition has gained increasing popularity over the last few decades; however, the stand-off distance in a conventional iris recognition system is too short, which limits its application. In this paper, we propose a novel hardware–software hybrid method to increase the stand-off distance in an iris recognition system. When designing the system hardware, we use an optimized wavefront coding technique to extend the depth of field. To compensate for the blurring of the image caused by wavefront coding, on the software side, the proposed system uses a local patch-based super-resolution method to restore the blurred image to its clear version. The collaborative effect of the new hardware design and software post-processing showed great potential in our experiment. The experimental results showed that such improvement cannot be achieved by using a hardware-or software-only design. The proposed system can increase the capture volume of a conventional iris recognition system by three times and maintain the system’s high recognition rate.

Artefacts and noise degrade the decoded image of a wavefront coding infrared imaging system, which usually results in the decoded image being inferior to the in-focus infrared image of a conventional infrared imaging system. The previous letter showed that the decoded image fell behind the in-focus infrared image. For comparison, a bar target experiment at temperature of ﹢20°C and two groups of outdoor experiments at temperatures of ﹢28°C and ﹢70°C are respectively conducted. Experimental results prove that a wavefront coding infrared imaging system can achieve the decoded image being approximating to its corresponding in-focus infrared image.

The cubic phase mask is known to cause significant changes of point spread function (PSF) as the angle of view increases. view. Instead of the conventional on-axis PSF in the best focal plane, we utilized the arithmetic-average of PSFs at various angles of view to generate the deconvolution filter for wavefront coding, and confirmed that the effective angle of view was successfully expanded about 1.6 times than conventional.

Wavefront coding[1] is the most commonly used method of extending the depth of field (DOF). In this method, the DOF is extended by phase modulation of the pupil function using a cubic phase mask and digital processing using a deconvolution filter. We propose a new aperture for the system that extends the DOF and suppresses artifacts.

We achieved a significant extension of the depth of field for a laser-scanning barcode reader by wavefront coding with a cubic phase mask. If the present method is adopted in a laser-scanning barcode reader, a decrease in the frequency of reading failure is expected.

Imaging samples with a depth in excess of the depth of field of the objective poses a serious challenge in microscopy. The available techniques such as focus-stacking accomplish the task; however, besides necessitating complicated optical and mechanical arrangements, these techniques often exhibit very long acquisition times. As a result, their applicability is limited to static samples. We describe a simple and practical hybrid 3D imaging technique which permits the acquisition of 3D images in a single snapshot. Additionally, the proposed method solves the post-recovery artefact formation problem which plagues hybrid imaging systems; thus, enabling high-quality, artefact-free images to be obtained. Experimental results indicate that this method can yield an image quality comparable to that given by a focus-stack (which can require up to a few hundred snapshots) from a single snapshot.

While the performance of optical imaging systems is fundamentally limited by diffraction, the design and manufacture of practical systems is intricately associated with the control of optical aberrations. The fundamental Shannon limit for the number of resolvable pixels by an optical aperture is generally therefore not achieved due to the presence of off-axis aberrations or large detector pixels. We report how co-called computational-imaging (CI) techniques can enable an increase in imaging performance using more compact optical systems than are achievable with traditional optical design. We report how discontinuous lens elements, either near the pupil or close to the detector, yield complex and spatially variant PSFs that nevertheless provide enhanced transmission of information via the detector to enable imaging systems that are many times shorter and lighter than equivalent traditional imaging systems. Computational imaging has been made possible and attractive with the trend for advanced manufacturing of aspheric, asymmetric lens shapes at lower cost and by the exploitation of low-cost, high-performance digital computation. The continuation of these trends will continue to increase the importance of computational imaging.

Wavefront coding, a technique of optical-digital hybrid image, can be used to extend the depth of the field. However, it sacrifices the signal-to-noise ratio (SNR) of system at a certain degree, especially on focus situation. The on-focus modulation transfer function (MTF) of wavefront coding system is much lower than that of generally traditional optical system. And the noise will be amplified in the digital image processing. This paper analyzes characteristics of the SNR of the wavefront coding system in the frequency domain and calculates the rate of noise amplification in the digital processing. It also explains the influence of the image detector noise severely reducing the restored quality of images. In order to reduce noise amplification in the process of image restoration, we propose a modified wiener filter which is more suitable for restoration in consideration of noise suppression. The simulation experiment demonstrates that the modified wiener filter, compared with traditional wiener filter, has much better performance for wavefront coding system and the restored images having much higher SNR in the whole depth of the field.

A novel method for broadband imaging of using a diffractive photon sieves is proposed and experimentally demonstrated. Unlike conventional photon sieves imaging in which clear imaging is only valid at a single designed wavelength due to the strong wavelength-dependent nature of diffractive elements, broadband photon sieves imaging is implemented with wavefront coding of a simple cubic phase mask without complicated optical system to compensate large chromatic aberration. Experimental validation was performed using an UV-lithography fabricated photon sieves of a focal length of 500mm and a diameter of 50mm at designed wavelength 632.8nm and a diamond-turning fabricated cubic phase mask of a phase parameter α=20π. Results show that extension of the working bandwidth of the proposed photon sieves imaging system is at least 88 times that of a conventional one with almost the same optical resolution and much increased energy efficiency. The proposed method suggests a new concept of extending the applications of photon sieves to work in a broadband wavelength range with a simple method in contrast to conventionally work at a single wavelength only.

Wavefront coding (WFC) technology is adopted in the space optical system to resolve the problem of defocus caused by temperature difference or vibration of satellite motion. According to the theory of WFC, we calculate and optimize the phase mask parameter of the cubic phase mask plate, which is used in an on-axis three-mirror Cassegrain (TMC) telescope system. The simulation analysis and the experimental results indicate that the defocused modulation transfer function curves and the corresponding blurred images have a perfect consistency in the range of 10 times the depth of focus (DOF) of the original TMC system. After digital image processing by a Wiener filter, the spatial resolution of the restored images is up to 57.14 line pairs/mm. The results demonstrate that the WFC technology in the TMC system has superior performance in extending the DOF and less sensitivity to defocus, which has great value in resolving the problem of defocus in the space optical system.

The revolution in dual-band infrared focal plane arrays over the past ten years has induced a significant impact on dual-band imaging system design. There are numerous challenges facing dual-band imaging system design using traditional methods. In this paper, Wavefront Coding technique is used to offer the potential implementation of infrared dual-band achromatic and diffraction-limited imaging by using simple optics. An example in terms of a one-element dual-band infrared imager is given.

The development of nanoscale single-molecule localization and tracking technology for multiple bio-molecules in intact cells has important significance for studying the dynamic process in life process. Since most of cells are several microns in depth, but the focal depth of traditional optical microscopes are less than one micron, the limited depth of field is the main drawback of conventional single molecular localization microscopy that prevents observation and tracking of multiple molecules in intact cells. In this paper, based on the wavefront coding technique, a new type of holographic phase plate with high efficiency is proposed and designed to extend the depth of field of single molecular localization microscopy, which combines the distorted multi-value pure-phase grating (DMVPPG) with the double-helix point spread function (DH-PSF). The DMVPPG can be used to realize multiplane imaging of several tens of layers of a sample in a single detection plane. And the DH-PSF is an engineered point spread function which encodes the lateral and axial position with high precision of a molecule in the center of its two lobes and the angle between them respectively. Using the combined holographic phase plate, the molecules in dozens layers of a whole cell can be simultaneously imaged on the same detection plane with DH-PSF. Not only can the axial resolving power be improved, but the imaging depth can also be extended without scanning. Adding such a holographic phase plate to the imaging path, the limited imaging depth problem in single-molecule-localization microscopy can be solved without sacrificing the localization accuracy. The proposed new type of holographic phase plate can also be implemented with a spatial light modulator. In the following numerical simulation experiments, the designed holographic phase plate is composed of 600×600 pixels with a pixel size of 10 μm. The distance between two adjacent focal planes is designed to be 0.5 μm. Such a holographic phase plate is placed on the Fourier transform plane of the detection light path. When an emitter is located on the focal plane, it can be imaged as two lobes without rotation in a center area of the field of view. If an emitter is -6 μm away from the focal plane, the DH-PSF appears in the upper-left area of the field of view. Simulation results demonstrate that a total of 25 sample layers can be simultaneously imaged on the single detection plane and the 12 μm detection range can be achieved, thus proving the feasibility of this method.

We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront coding in imaging optical systems. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront coding in imaging optical systems. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront coding in imaging optical systems. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We demonstrate 3D microscope imaging using computational optical sectioning microscopy (COSM) with an engineered point-spread function (PSF) robust to depth-induced spherical aberration (SA). Earlier we demonstrated that wavefront encoding (WFE) using a squared cubic (SQUBIC) phase mask reduces the PSF depth-variance in the presence of SA and that space-invariant (SI) restoration of simulated images using a single WFE-PSF does not lead to artifacts as in the conventional case. In this study, we show experimental verification of our WFE COSM approach. The WFE system used is a commercial microscope with a modified side port imaging path, where a spatial light modulator projects the SQUBIC phase mask on the back focal plane of the imaging lens. High resolution images of a test sample with 6 μm in diameter microspheres embedded in UV-cured optical cement (RI = 1.47) were captured using both the engineered and the conventional imaging paths of the system. The acquired images were restored using a regularized SI expectation maximization algorithm based on Tikhonov-Miller regularization with a roughness penalty. A comparative study quantified in terms of the correlation coefficients between the XZ medial sections of the restored images, from experimental data, shows an 11% reduction in depth sensitivity in the SQUBIC system compared to the conventional system.

A functional approach to the multivariate statistical model of a generalized incoherent passive optical ranging and imaging system with a CCD sensor is proposed. This approach implies that a large number of discrete, statistically independent, random data (pixel readouts) can be approximated by a continuous random function. Thus, the joint probability density function (PDF) takes a functional form; the statistical averages of the infinite-variate PDF and the Fisher information become functional integrals that can be treated analytically in the Gaussian approximation. The Cramer–Rao bounds on estimator-error variances are obtained for the scalar and functional deterministic parameters of the model. An approximate expression is derived for the PDF of the sum of independent Gaussian and Poisson random variables using the steepest-descent method, and the resulting PDF is shown to be asymptotically Gaussian. As an illustration, we apply the developed approach to a passive optical rangefinder with chiral wavefront coding. Numerical and experimental examples are presented.

Treball final de màster oficial fet en col·laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB) i Institut de Ciències Fotòniques (ICFO) Light sheet fluorescence microscopy (LSFM) is used in many biological research experiments that require fast three-dimensional (3D) imaging up to a few volumes per second. Wavefront coding (WFC) microscopy provides LSFM with 3D real-time imaging capabilities introducing a controlled aberration that extends the depth of field (DOF) of the microscope objective. Resulting images, however, are blurred and need to be processed to recover the original sharpness in a CPU-intensive deconvolution which makes real-time visualization unattainable. We present computational tools based on GPU parallel computing to achieve real-time deconvolution and visualization of the images obtained with WFC light-sheet microscopy. La Microscopía de Fluorescencia de Iluminación plana (LSFM) se utiliza en muchos experimentos de investigación que requieren la obtención rápida de imágenes en tres dimensiones (3D) a velocidades de unos pocos volúmenes por segundo. La codificación de frente de onda (WFC) proporciona a LSFM la capacidad de obtener imágenes en 3D en tiempo real mediante la introducción de una aberración controlada que amplía la profundidad de campo (DOF) del objetivo del microscopio. Las imágenes obtenidas, no obstante, están difuminadas y necesitan de un procesado para recuperar su nitidez original en una operación de deconvolución que requiere un uso intensivo de la CPU y que impide su visualización en tiempo real. Se presentan herramientas computacionales basadas en procesamiento en paralelo en la GPU que permiten la deconvolución y visualización de imágenes obtenidas con un microscopio WFC de fluorescencia de iluminación plana. La Microscòpia de Fluorescència d’Il·luminació plana (LSFM) es fa servir en molts experiments de recerca que requereixen l’obtenció ràpida d’imatges en tres dimensions (3D) a velocitats d’uns pocs volums per segon. La codificació de front d’ona (WFC) proporciona a LSFM la capacitat d’obtenir imatges en 3D en temps real mitjançant la introducció d’una aberració controlada que amplia la profunditat de camp (DOF) de l’objectiu del microscopi. Tanmateix, les imatges obtingudes estan difuminades i necessiten d’un processat per recuperar la seva nitidesa original en una operació de deconvolució que requereix d’un ús intensiu de la CPU i que impedeix la seva visualització en temps real. Es presenten eines computacionals que permeten la deconvolució i visualització d’imatges obtingudes amb un microscopi WFC de fluorescència d’il·luminació plana.

The random selection of phase mask parameters will cause the degradation of imaging quality, which can be fixed through the optimization process. We introduce an evaluation function based on the use of multitarget optimization to obtain optimal phase mask parameters. The proposed method gives the optimal phase mask parameters, which produce together an imaging quality at all defocus positions as best as possible. The cubic phase mask and the general cubic phase mask are both used to perform optimization with a proposed evaluation function. The simulation result gives quite interesting values for the two types of these phase masks.

Simulated results demonstrate the impact of detector noise on the design of a broadband wavefront coded optical system. We conclude that noise must be included as a first-order design constraint in cubic phase-encoded systems.

Artificial compound-eye optics have been used for three-dimensional information acquisition and display. It also enables us to realize a diversity of coded imaging process in each elemental optics. In this talk, we introduce our single-shot compound-eye imaging system to observe multi-dimensional information including depth, spectrum, and polarization based on compressive sensing. Furthermore it is applicable to increase the dynamic range and field-of-view. We also demonstrate an extended depth-of-field (DOF) cameras based on compound-eye optics. These extended DOF cameras physically or computationally implement phase modulations to increase the focusing range.

Light field microscopy has been proposed as a new high-speed volumetric computational imaging method that enables reconstruction of 3-D volumes from captured projections of the 4-D light field. Recently, a detailed physical optics model of the light field microscope has been derived, which led to the development of a deconvolution algorithm that reconstructs 3-D volumes with high spatial resolution. However, the spatial resolution of the reconstructions has been shown to be non-uniform across depth, with some z planes showing high resolution and others, particularly at the center of the imaged volume, showing very low resolution. In this paper, we enhance the performance of the light field microscope using wavefront coding techniques. By including phase masks in the optical path of the microscope we are able to address this non-uniform resolution limitation. We have also found that superior control over the performance of the light field microscope can be achieved by using two phase masks rather than one, placed at the objective’s back focal plane and at the microscope’s native image plane. We present an extended optical model for our wavefront coded light field microscope and develop a performance metric based on Fisher information, which we use to choose adequate phase masks parameters. We validate our approach using both simulated data and experimental resolution measurements of a USAF 1951 resolution target; and demonstrate the utility for biological applications with in vivo volumetric calcium imaging of larval zebrafish brain.

We systematically compared the optical performance of two computational photography (CP) approaches used to extend the depth of field of an imaging system: wavefront coding and lattice focal lens imaging. A test bed was developed by translating test resolution targets through the focal plane of a high magnification telescope placed 25 meters away. We demonstrated an increase in depth of field from 2 cm to 20 cm in each case. We found qualitative differences in restored image quality that depend both on the CP modality and signal to noise. A comparison of results in the frequency domain suggests optimization strategies for computational photography when the frequency content of imaged objects is known ahead of time.

We describe the application of wavefront coding technique for infrared imaging system to control thermal defocus. For traditional infrared imaging system, athermalization is necessary to maintain imaging performance which may increase complexity and cost of the imaging system. Wavefront coding includes a phase mask at the pupil which can re-modulate wave front so as to produce an encoded image. After digital processing, the system is insensitive to defocus. In this paper, the combination of wavefront coding technique and infrared imaging system has been discussed. We report here the optic design of the wavefront coding IR system based on Zemax. The phase mask is designed to ensure that the modulation transfer function (MTF) is approximately invariant in the range of working temperature. Meanwhile, we designed three IR systems to put up contrast experiments. System one and two are designed to compare the influence before and after the insertion of phase mask. System three is designed to compare the imaging performance before and after reducing lens in wavefront coding IR system. The simulation results show that the infrared imaging system based on wavefront coding can control thermal defocus in a temperature varying from -60oC to 60 oC, at the same time the weight and cost of optical elements are reduced by approximately 40%.

Wavefront coding (WFC) uses a special aspheric optics and digital image processing to extend the depth of focus in imaging systems. An intermediate blurred image is generated by the spatial convolution of the image with the point spread function (PSF) of a cubic phase mask. Restoration tests are performed on an optically encoded image. The best option to restore an image is not always given by a deconvolution method using the PSF of the imaging system. Due to it is limited by the perfect PSF of the system. In this study, the restored image is given by a deconvolution method using the numerical PSF. As the quality of the image is depended of the pupil diameter and strength of the wfc phase plate, an optimization was achieved by means of measuring the decoded image contrast. Results shows a high resolution decoded image.

A wave-front coded imaging system is an optical-digital method for aberration control. Wave-front coding technology incorporates an aspheric element in the optical system in order to capture a coded image and by digital processing decode it to obtain the final image. The WFC system is very insensitive to defocus-like aberrations and thereby becomes a tool in the aberration balancing for telescope systems. We propose WFC technology to be implemented in a two spherical mirror telescope. In this work we present the design and simulation of the proposed telescope, trade-offs encountered in the design process and aspects of the image restoration.

Wavefront coding as an optical-digital hybrid imaging technique can be used to extend the depth of field. The key to wavefront coding lies in the design of suitable phase masks to achieve the invariant imaging properties over a wide range of defocus. In this Letter, we propose another phase mask with a tangent function to enrich the odd symmetrical kind of phase masks. The performance of the tangent phase mask is evaluated by comparison with a cubic mask, improved-1 logarithmic mask, improved-2 logarithmic mask, and sinusoidal mask. The results demonstrate that the tangent phase mask has superior performance in extending the depth of field.