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- Front Matter: Volume 7429
- Design in Computed Imaging I
- Illumination
- Modeling
- Systems
- Design in Computed Imaging II
- Education
- Posters Session
Front Matter: Volume 7429
Front Matter: Volume 7429
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This PDF file contains the front matter associated with SPIE Proceedings Volume 7429, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.
Design in Computed Imaging I
Low-complexity digital filter geometry for spherical coded imaging systems
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Recent research in the area of electro-optical system design identified the benefits of spherical aberration for
extending the depth-of-field of electro-optical imaging systems. In such imaging systems, spherical aberration
is deliberately introduced by the optical system lowering system modulation transfer function (MTF) and then
subsequently corrected using digital processing. Previous research, however, requires complex digital postprocessing
algorithms severely limiting its applicability to only expensive systems. In this paper, we examine the
ability of low-cost spatially invariant finite impulse response (FIR) digital filters to restore system MTF degraded
by spherical aberration. We introduce an analytical model for choosing the minimum, and hence cheapest, FIR
filter size capable of providing the critical level sharpening to render artifact-free images. We identify a robust
quality criterion based on the post-processed MTF for developing this model. We demonstrate the reliability
of the estimated model by showing simulated spherical coded imaging results. We also evaluate the hardware
complexity of the FIR filters implemented for various spherical aberrations on a low-end Field-Programmable
Gate Array (FPGA) platform.
Optimality of pupil-phase profiles for increasing the defocus tolerance of hybrid digital-optical imaging systems
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A phase mask at the aperture stop of a hybrid digital-optical imaging system can improve its tolerance to aberrations.
The choice of the introduced phase modulation is crucial in the design of such systems. Several successful phase masks
have been described in the literature. These masks are typically derived by searching for optical-transfer-functions that
retain restorability under aberrations such as defocus. Instead of optimizing the optical-transfer-function for some desired
characteristics, we calculate the expected imaging error of the joint design directly. This was used to compare thirddegree
polynomial phase masks, including the cubic phase profile and a commonly used generalization. The analysis
shows how the optimal phase profile depth is always limited by noise and more importantly, numerical simulations show
that only a finite range of the third-degree polynomial profiles yield optimal performance.
Depth of field extension in a low power microscope objective
Show abstract
Three different techniques for extending the depth of field of a low-power (4x) microscope objective system are examined experimentally: wavefront coding with a cubic phase mask, amplitude modulation with a large central obscuration, and added spherical aberration. Their relative merits are discussed and demonstrated with sample images.
Depth perception with a rotationally symmetric coded camera
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A novel design of a phase coded depth-sensing camera is presented. A rotational symmetric phase mask is designed to
discriminate the point spread functions (PSF) from different scene distances. The depth information can then be
computationally obtained from a single captured photograph through a phase coded lens. The PSF must be carefully
optimized at off-axis angles in order to create a restored image which is sharp over the required field of view. In this
paper, a phase coded depth camera with a focal length 10.82mm, sensor size 2mm and F-number 5 is designed.
Simulation data is exchanged between Matlab and Zemax for co-optimization of optical coding and digital decoding
process. The simulation result shows that coarse depth information is investigated for object distance from 513 mm to
1000 mm.
Infrared image guidance for ground vehicle based on fast wavelet image focusing and tracking
Show abstract
We studied the infrared image guidance for ground vehicle based on the fast wavelet image focusing and tracking.
Here we uses the image of the uncooled infrared imager mounted on the two axis gimbal system and the developed new
auto focusing algorithm on the Daubechies wavelet transform.
The developed new focusing algorithm on the Daubechies wavelet transform processes the result of the high pass filter
effect to meet the direct detection of the objects. This new focusing gives us the distance information of the outside
world smoothly, and the information of the gimbal system gives us the direction of objects in the outside world to match
the sense of the spherical coordinate system.
We installed this system on the hand made electric ground vehicle platform powered by 24VDC battery. The electric
vehicle equips the rotary encoder units and the inertia rate sensor units to make the correct navigation process. The
image tracking also uses the developed newt wavelet focusing within several image processing.
The size of the hand made electric ground vehicle platform is about 1m long, 0.75m wide, 1m high, and 50kg weight.
We tested the infrared image guidance for ground vehicle based on the new wavelet image focusing and tracking using the electric vehicle indoor and outdoor. The test shows the good results by the developed infrared image guidance for
ground vehicle based on the new wavelet image focusing and tracking.
Illumination
Chromatic perception of non-invasive lighting of cave paintings
Show abstract
This work is intended to deal with the problems which arise when illuminanting Paleolithic cave paintings. We have
carried out the spectral and colorimetric characterization of some paintings located in the Murcielagos (bats) cave
(Zuheros, Córdoba, Spain). From this characterization, the chromatic changes produced under different lighting
conditions are analysed. The damage function is also computed for the different illuminants used. From the results
obtained, it is proposed an illuminant whose spectral distribution diminishes the damage by minimizing the absorption of
radiation and optimises the color perception of the paintings in this cave. The procedure followed in this study can be
applied to optimise the lighting systems used when illuminating any other art work
Efficient measurement of large light source near-field color and luminance distributions for optical design and simulation
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The color and luminance distributions of large light sources are difficult to measure because of the size of the source and
the physical space required for the measurement. We describe a method for the measurement of large light sources in a
limited space that efficiently overcomes the physical limitations of traditional far-field measurement techniques. This
method uses a calibrated, high dynamic range imaging colorimeter and a goniometric system to move the light source
through an automated measurement sequence in the imaging colorimeter's field-of-view. The measurement is performed
from within the near-field of the light source, enabling a compact measurement set-up. This method generates a detailed
near-field color and luminance distribution model that can be directly converted to ray sets for optical design and that
can be extrapolated to far-field distributions for illumination design. The measurements obtained show excellent
correlation to traditional imaging colorimeter and photogoniometer measurement methods. The near-field goniometer
approach that we describe is broadly applicable to general lighting systems, can be deployed in a compact laboratory
space, and provides full near-field data for optical design and simulation.
A beam splitter of natural light guiding system based on dichroic prism for ecological illumination
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In thremmatology, many researches focus on ecological illumination for improving the growing speed of animal or
plant. According to the Trichromatic theory, any specific color can be made up of red, green, and blue light. Sunlight has
full spectrum so it is the most applicable source. A Natural Light Guiding System includes collecting, transmitting, and
lighting parts. In our research, we would like to design a beam splitter in the transmitting part to separate the sunlight
into red, green, and blue light for ecological illumination. We use high pass and low pass dichroic coatings in a prism,
called dichroic prism, to be the beam splitter to separate the wavelength. For measuring the spectra of the exit beams, we
build a space with the Natural Light Guiding System. In the space, the spectra of sunlight outside and inside the space
and the exit beams of the beam splitter are measured. Finally, we use prismatic structure to design the beam splitter, and
optimize the surface of the element with aspheric surface and Fresnel surface to reduce the beam angle of exit light.
Design and optimization of dot pattern in illumination lightpipe of natural light guiding system
Show abstract
In recent years, the practicality and importance of the illumination with sunlight are getting more seriously concern
in public. The reason is that natural light is non-polluting, energy-saving, and healthy in comparison with traditional light
sources. Therefore, our research focuses on how to replace the artificial sources by natural light. A Natural Light Guiding
System has collecting, transmitting, and lighting parts. For replacing the traditional sources, the lighting part should have
similar characteristic, such as intensity distribution and geometric parameters, to artificial sources. In this paper, we
design, simulate, and optimize illumination lightpipe with dot pattern to redistribute the collecting sunlight from Natural
Light Guiding System. The lightpipe includes input, system, and output parts. In the input part, we design a coupler to
improve the coupling efficiency with natural light. For optimizing the efficiency of the coupler, we evaluate the
relationship between the distance that is from the fiber to the lightpipe and the coupled power. In the system part, the
sunlight is locked by total internal reflection, TIR, so we design dot pattern to scatter the locked sunlight for uniform
lighting. In the output part, a uniform illumination is our goal. For designing the percentage of the surface will be
covered by dot pattern, we offer a design theory and simulate the efficiency.
Modeling
Overview of the SMS design method applied to imaging optics
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The Simultaneous Multiple Surfaces (SMS) was developed as a design method in Nonimaging Optics during the 90s.
Later, the method was extended for designing Imaging Optics. We present an overview of the method applied to imaging
optics in planar (2D) geometry and compare the results with more classical designs based on achieving aplanatism of
different orders. These classical designs are also viewed as particular cases of SMS designs. Systems with up to 4
aspheric surfaces are shown.
The SMS design strategy is shown to perform always better than the classical design (in terms of image quality).
Moreover, the SMS method is a direct method, i.e., it is not based in multi-parametric optimization techniques. This
gives the SMS method an additional interest since it can be used for exploring solutions where the multiparameter
techniques can get lost because of the multiple local minima.
Raytrace assisted analytical formulation of Fresnel lens transmission efficiency
Show abstract
In consideration of the broad range of possible Fresnel lens applications, it is desirable to find a fast way of
approximating optical performance that is not specific to a particular lens geometry. This is potentially useful
for gaining deeper insight into a lens system and affording accelerated development times.
Additionally, a Fresnel lens manufactured using a molded polymer process has limitations on how accurately
it can replicate a microstructured prismatic pattern. This is especially true at the prismatic peaks of the part
where it is more difficult to completely "fill-out" the moldbase. Inclusion of this effect in performance evaluation
is important.
Using transmission efficiency (or transmittance) as the metric, a Fresnel lens model which includes imperfect
peak replication is sought. The system description will be parameterized so that the formulations are not specific
to a particular geometry and can be generally applied. The parameter space will be explored with raytracing
and the results compiled for convenient reference.
Design, analysis, and fabrication of a really bad lens
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Many practical singlet lenses (with one aspheric and one planar surface) can be designed analytically without resorting to
iterative optimization. "Good" lenses that precisely focus or collimate monochromatic light are covered first. Then a
less important but more interesting "bad" case is discussed. An unusual application required a singlet lens whose axial
caustic is an order-of-magnitude greater than its paraxial focal length. A lens with a radial spline surface was designed
using the CodeV and ASAP macro languages. The near-field on-axis diffraction irradiance produced by the lens was
verified using the ASAP software's beamlet decomposition/summation capability. Specification of the surface for
manufacture seemed straightforward but became problematic due to limitations at the time in the software used by the
computer-controlled grinding and polishing machines. Eventually the lens was manufactured successfully but only after
fitting the spline to a standard radial polynomial (including odd terms).
Optimization of optics with micro diffractive optical element via a hybrid Taguchi genetic algorithm
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This paper proposes a new method for optimization optics with a diffractive optical element (DOE) via a Hybrid
Taguchi Genetic Algorithm. A Diffractive Optical Element, based the theory of wave phase difference, takes advantage
of the negative Abbe number which might significantly eliminate the axial chromatic aberrations of optics. Following
the advanced technology applied to the micro lens and etching process, precisely-made micro DOEs can now be
manufactured in large numbers. However, traditional least damping square has its limitations for the optimization of
axial and chromatic aberrations with DOE. In this research, we adopted the genetic algorithm (GA) and incorporated the
steady Taguchi method into GA. Combining the two methods produced a new hybrid Taguchi-genetic algorithm
(HTGA). Suitable glass combinations and DOE positions were selected to minimize both axial and lateral chromatic
aberration in the optical system. This new method carries out the task of eliminating both axial and lateral chromatic
aberration, unlike DOE optimization by LDS, which works for axial aberration only and with less efficiency. Experiments show that the surface position of the DOE could be determined first; in addition, regardless of whether chromatic aberration was axial or longitudinal, issues concerning the optical lens's chromatic aberration could be significantly reduced, compared to results from the traditional least damping square (LDS) method.
Systems
Flight miniature Risley prism mechanism
Show abstract
More optical engineers are choosing to use Risley prism devices to accomplish alignment and steering of optical
systems. A Risley prism device consists of a pair of rotating wedged optic elements that redirect rays of light by
refraction. By rotating each wedge independently, the originating ray can be steered to a new angle or translated within a
cone respective of the wedge angle and separation of the prism pair. The automated miniature Risley mechanism
(MRM) was designed and tested for space flight where the physical envelope was significantly constrained, only very
low power was available, and a unique power-off hold function was required. The MRM incorporates a prism pair with
a 19 mm clear aperture and 0.75° wedge angle; it performs at 6 rpm (maximum speed) with a beam deflection accuracy
of 25 μrad, and a power-off holding accuracy of 8 μrad within a 64 mm (optic axis) by 58 mm (height & width)
envelope. This paper describes the driving requirements for the MRM and how the MRM assembly was successfully
tested to verify its space flight performance requirements. Some design features included in the MRM assembly are: the
radial titanium isothermal optical flexure mounts, a direct-drive zero-cog motor, a 37 Hz bandwidth closed-loop control
system; a unique inductive position sensing system; and a fail-safe flexure-type brake assembly.
Collection optics for imaging spectroscopy of an electric arc shock tube
Show abstract
A system of collection optics was designed and built to perform imaging spectroscopy on shock waves created in the
Electric Arc Shock Tube (EAST) at NASA Ames Research Center. This reflective system has four channels and collects
radiation wavelengths that span from the vacuum ultraviolet to the near-infrared (120-1700nm). A telecentric object
space minimizes blur along the direction of propagation of the shock wave. Additional fold mirrors preserve image
orientation and cause the system to be symmetric with respect to the spectrometer entrance slits. The aperture is
angularly segmented to allow more than one channel on each side of the shock tube. Optical/mechanical design trade
studies, photographs of the as-built system and sample data are presented.
Laser despeckled image
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The objective of this work is the suppression of speckles in an image illuminated by a remote laser.
This is accomplished by a novel method in which the illuminating laser beam propagates through a
multimode fiber dithered at an arbitrary section, then passes through a microlens array prior to
illuminating the image generator. Thereby the speckle contrast is reduced to its minimum value for
dithering frequencies of at least 25 Hz, attaining a magnitude speckle contrast of less than 12%, and
illumination homogeneity across the illumination filed of less than 20%.
Speckle interferometric sensor to measure low-amplitude high frequency ocular microtremor (OMT)
Show abstract
Ocular microtremor (OMT) is a physiological high frequency (up to 150Hz) low amplitude (150-2500nm) involuntary
tremor of the human eye. It is one of the three fixational ocular motions described by Adler and Fliegelman in 1934 as
well as microsaccades and drift. Clinical OMT investigations to date have used eye-contacting piezoelectric probes or
piezoelectric strain gauges. Before contact can be made, the eye must first be anaesthetised. In some cases, this induces
eyelid spasms (blepharospasm) making it impossible to measure OMT. Using the contact probe method, the eye motion
is mechanically damped. In addition to this, it is not possible to obtain exact information about the displacement. Results
from clinical studies to date have given electrical signal amplitudes from the probe. Recent studies suggest a number of
clinical applications for OMT, these include monitoring the depth of anaesthesia of a patient in surgery, prediction of
outcome in coma, diagnosis of brainstem death. In addition to this, abnormal OMT frequency content is present in
patients with neurological disorders such as Multiple sclerosis and Parkinson's disease. However for ongoing clinical
investigations the contact probe method falls short of a non-contact accurate measurement solution. In this paper, we
design a compact non contact phase modulating optical fiber speckle interferometer to measure eye motions. We present
our calibration results using a calibrated piezoelectric vibration simulator. Digital signal processing is then performed to
extract the low amplitude high frequency displacement information.
Analysis of required shape of flexible sensor for different lens focus
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The purpose of this study is to find the shape requirement of image sensors when catching the image to obtain a much
clear image than the flat image sensor. The results are applied to an o-ring driven liquid filled lens. It was found that the
image distortion of the liquid filled lens is inevitable. Therefore, it is necessary to design an curved image sensor which
can compensate the image distortion to solve this problem. The shape of the image sensor can be predicted by computer
simulation. The required shape of the image sensor can be obtained by deforming the PDMS (Polydimethylsiloxane)
membrane. The deformation of PDMS membrane of lens and the image sensor film can be obtain by using ANSYS®
software at variable internal pressure in the liquid filled lens. The experimental module is composed of a barrel,
transparent liquid (De-ionized water), PDMS lens membrane, rigid ring of lens curvature control, adjustable accessories
of lens curvature orientation, the image sensors which are constructed on PDMS film, rigid ring of sensor film curvature
control, and adaptable accessories of sensor film variable curvature adjustment. The ring of sensor film and accessories
are utilized for variable sensor film's curvature control. On the basis of lens curvature's modulation, the image sensor
film tuning process makes the image sensors on the optimal plane.
Design in Computed Imaging II
Ray tracing, wavefronts, and caustics: use of Shack-Hartmann wavefront sensor for analyzing light propagation
Show abstract
Wavefront measurements are a key point in the development of imaging techniques. Nowadays, a common tool for these
measurements is the Shack-Hartmann sensor, where the results are often given in terms of the Zernike polynomials. The
interpretation of the results, as one moves the Shack-Hartmann sensor in the axial zone, is sometimes difficult as it
involves the task of visualizing the geometrical propagation of the wavefront. We present a numerical tool based on ray
tracing that visualizes wavefronts and caustics as the beam propagates and enables the calculation of the Zernike
polynomials at any intermediate stage.
Spherical coded imagers: improving lens speed, depth-of-field, and manufacturing yield through enhanced spherical aberration and compensating image processing
Show abstract
Recently, joint analysis and optimization of both the optical sub-system and the algorithmic capabilities of
digital processing have created new digital-optical imaging systems with system-level benefits. We explore
a special class of digital-optical imaging systems called spherical coding that combine lens systems having
controlled amounts of spherical aberration with digital sharpening filters to achieve fast, low-cost, extended
depth-of-field (EDoF) imaging systems. We provide analysis of the optimal amount of spherical aberration
required as a function of desired depth-of-field extension. We also characterize the MSE-optimal filters
required to restore contrast. Finally, we describe a simple method to designing spherical coded systems and
demonstrate several advantages such as improved manufacturing yield using an actual lens design.
A technique to remove image artefacts in optical systems with wavefront coding
Show abstract
Based on an analytical analysis of the optical transfer function in an optical system with wavefront coding, specifically
with a cubic phase mask in the aperture stop, we explain that such systems have image artefacts in the restored images
and that these are manifested as replication artefacts. To remove image artefacts we propose to store a set of defocused
point spread functions such that a single defocused image can be restored to a set of images, wherein one of them is
without image artefacts. The image without image artefacts is determined with a new metric which we define in the
wavelet domain.
Education
Case study findings of PHOTON problem-based learning (PBL) with high school photonics outreach programs
Show abstract
Using the Photonics Leaders program model, recruitment and retention, photonics content, parental
engagement, internship, and PHOTON PBL challenges, the session's goal is to inform educators of
strategies that can be used to motivate and develop cognitive skills in the discipline of Physics. The
program caters to ethnically diverse students who traditionally lack experiences in the discipline. This
paper discusses the initial findings of the National Science Foundation (NSF) Innovative Technology
Experiences for Students and Teachers (ITEST) program through which high school students and teachers
were given the opportunity to participate in shared lessons, and coordinate projects through cooperative
learning at The Science House at North Carolina State University.
Restarting a high school photonics program
Show abstract
Following a severe drop in enrollment, one high school's photonics program was in jeopardy of being eliminated.
Instead, the program was rejuvenated and expanded and now meets the needs of more students than ever. In this paper,
we describe how various resources were combined to improve methods of instruction (specifically, through problembased
learning, or PBL), enhance classroom/real-world integration, and solidify the role this program plays within the
school's larger science and technology curriculum (recently revised to meet new state guidelines). Instructor
participation in the New England Board of Higher Education (NEBHE) PHOTON projects, funded by the National
Science Foundation, was key.
Teaching photonics technology students to think: methods
Show abstract
This paper describes different methods used in the classroom and lab to teach photonics technology students to think. When students transcend from the classroom to the work environment, they must be able to think and problem solve without a teacher, instructor, or professor holding their hand during problem solving. There are many ways that can be used in the classroom to teach students to think. The methods discussed in this paper range from using thought provoking questions during lecture, to "full blown" project based learning methods, such as "Problem Based Learning".
An optics first year experience course for community college students
Show abstract
A common complaint about entering college students is that they are not prepared for the college experience. In response
to the problem, many colleges and universities offer "first year experience" (FYE) courses that provide a transition to the
college experience, promote academic success and enhance learning. In this paper we describe a first semester optics
course for community college students that is taught as an inquiry-based studio-type course. Introduction to Light and
Lasers incorporates many ideas of a first year experience course and addresses the issue of students underprepared in
mathematics, communication, critical thinking and hands-on laboratory skills.
Posters Session
A spherical catadioptric telescope system based on Cooke corrector group
Show abstract
To obtain a number of advantages in fabrication, testing and alignment, many designs in which spherical mirrors
replace classical Cassegrain-form aspheric mirrors are present in the literature. However, spherical mirrors suffer from
substantial spherical aberration and thereby require some form of corrector group. But in this case, the question
encountered is that of making the basic optical configuration more complex. In this paper, a new design based on Cooke
corrector group is presented for eliminating spherical aberration, which is believed to provide higher performance with
less complexity than previous approaches. Besides, the cost and fabrication period will be extremely decreased. The
telescope system using corrector group here can achieve good optical performance with f# of 10, full field of 0.5°,
obscuration of 1/3 and MTF (Modulation Transfer Function) of 0.48 corresponding to 50@lp/mm.
Depth of field estimation: theory, experiment, and application
Show abstract
When a fingerprint image is acquired via contactless means, the depth of field must be measured. Due to the natural
curvature of a finger, not all of the fingerprint will be in focus. Defocus introduced by such curvature may cause contrast
reduction, loss of certain spatial frequencies, blurriness, and contrast reduction and reversal. We need to ensure that the
imaging system has enough depth of field to compensate for the longitudinal displacement created by the finger
curvature. This paper presents theoretical and experimental techniques to simulate and measure the depth of field of an
imaging system. Experimentally, image contrast as a function of object position along the optical axis is measured for
several spatial frequencies of interest, and the defocused modulation transfer function (MTF) is determined. The
acceptable contrast range is defined by the system application and used to determine the corresponding depth of field. A
diffraction image irradiance theoretical model is developed, and the Zemax optical design program is used to simulate
depth of field. The experimental and simulated depth-of-field results are presented and applied to a contactless
fingerprint sensor.
Optical design of endoscopic shape-tracker using quantum dots embedded in fiber bundles
Show abstract
Colonoscopy is the current gold standard for colon cancer screening and diagnosis. However, the near-blind navigation
process employed during colonoscopy results in endoscopist disorientation and scope looping, leading to missed
detection of tumors, incorrect localization, and pain for the patient. A fiber optic bend sensor, which would fit into the
working channel of a colonoscope, is developed to aid navigation through the colon during colonoscopy. The bend
sensor is comprised of a bundle of seven fibers doped with quantum dots (QDs). Each fiber within the bundle contains a
unique region made up of three zones with differently-colored QDs, spaced 120° apart circumferentially on the fiber.
During bending at the QD region, light lost from the fiber's core is coupled into one of the QD zones, inducing
fluorescence of the corresponding color whose intensity is proportional to the degree of bending. A complementary
metal oxide semiconductor camera is used to obtain an image of the fluorescing end faces of the fiber bundle. The
location of the fiber within the bundle, the color of fluorescence, and the fluorescence intensity are used to determine the
bundle's bending location, direction, and degree of curvature, respectively. Preliminary results obtained using a single
fiber with three QD zones and a seven-fiber bundle containing one active fiber with two QDs (180° apart) demonstrate
the feasibility of the concept. Further developments on fiber orientation during bundling and the design of a graphical
user interface to communicate bending information are also discussed.
Development of tissue multi-slice laser reflectance imaging system
Show abstract
For early detection of abnormalities growing within the healthy tissues a laser based multi-slice reflectance measurement
technique is developed. The laser light is guided at the center of the probe. Around this the photo-detectors are arranged
symmetrically at various distances from the beam entry point. The optical radiations after scattering within the tissue
emerge at various locations which are detected by the detectors. After conversion from current to voltage these signals
are digitized and fed to computer. After pre-processing of the backscattered signals from 36 photo-detectors arriving
from various locations the reflectance images are reconstructed. As the detectors are placed at various distances from the
beam entry point in the form of rings, their respective images are obtained. These multi-slices images provide variation
in composition at various depths ranging from 2 - 7.5mm. Thus by placing the probe just once the required data for
images reconstruction is obtained. This is in contrast to earlier developments as this does not involve the movement of
the probe for image reconstruction. Based on the sequence of images from various depths a three - D image of the tissue
structure could also be obtained.
Structural design of optically compensated zoom lenses using genetic algorithm
Show abstract
A new approach for structural synthesis of optically compensated zoom lenses is reported. An implementation of
evolutionary programming facilitates the procedure by carrying out a global search over the available degrees of
freedom, namely, powers of the components and the inter-component separations. Practical success of the method
depends on suitable formulation of the fitness function. Normalization of the variables is carried out to get an insight on
the optimum structures. Illustrative numerical results are presented.
Illumination scheme for high-contrast contactless fingerprint images
Show abstract
Illumination is critical to achieve high-contrast, contactless fingerprint images. In this paper, we report results of
fingerprint imaging experiments performed under different illumination conditions. We studied how polarization states,
illumination wavelength, detection wavelength, and illumination direction influence the contrast of fingerprint images.
Our research findings provide a selection rule for optimum illumination and a basis for us to construct an illuminator that
generates uniform illumination and high-contrast contactless fingerprint images.
PDV and shock physics: application to nitro methane shock-detonation transition and particles ejection
Show abstract
Heterodyne Velocimetry (or Photonic Doppler Velocimetry) has turned out to be a major tool to study the
phenomena occurring in detonics and shock wave experiments. With accessible velocities ranging form a few m/s to
30,000 m/s, a very high sensitivity, a dynamics of more than 20 dB and a multi-velocity capability, one can understand
why this technique opens new fields of study.
This article is aimed at presenting an outlook of the setups and configurations which have been tested. We will connect
this outlook to a quick overview of different kinds of experiments that could be achieved.
In a first part we will remind how the system works. We will then detail the many setups that have already been put to
the test, with different possible hardware configurations responding to different uses and different probes aimed at
sensing specific phenomena. We also present our Matlab© based software developed to process the signals. Finally we
will go through the different applications on which PDV was implemented, both in a detonics context (free surface,
particles and Nitro Methane - or NM - characterization) and in lab experiments (measurement of laser driven shocks on
metallic targets).
Study on the reversibility of the diffraction light path
Show abstract
of grating. First, we studied the reversibility of optical path of grating illuminated by monochromatic light, and then
illuminated by polychromatic light. We found that the optical path of diffraction of grating has partial reversibility.
Using the partial reversibility of optical path of diffraction of grating, we analyzed the spectral combination
characteristic of grating and the bi-grating diffraction imaging effect.
A novel contactless aliveness-testing (CAT) fingerprint sensor
Show abstract
A contactless fingerprint sensor provides deformation-free, high-quality fingerprint images and offers users a cleaner and
more comfortable measurement environment. Here we propose and design an innovative prototype optical, contactless,
compact, fingerprint sensor that quickly produces high-quality, high-contrast interoperable fingerprint images. A proofof-
concept contactless, aliveness-testing (CAT) fingerprint sensor, which is connected to a PC via a firewire cable, was
constructed and is currently operating in our laboratory. The CAT sensor affords a more user-friendly interface
compared to existing contactless fingerprint sensors and also provides robust aliveness testing and spoof detection. In
this paper, we present the imaging system design concepts, finger aliveness detection techniques, and the user-friendly
interface approach. Various fingerprint matching results using the CAT sensor device are also presented and discussed.
Optical-fiber vortex-shedding flowmeter based on white-light interference
Show abstract
Optical-fiber vortex-shedding flowmeter is prospective in its application in the measurement field not only for the merits
up from vortex-shedding flowmeter but also those in optical fiber sensor such as flexibility, strong endurance, anti
electromagnetic interference capacity and adaptation in the flammable explosive environment. A new optical-fiber
vortex-shedding flowmeter based on white-light interference principle is introduced in this paper. Because of only
responding on dynamic disturbance, the all-fiber white-light interferometric flowmeter not only holds the high-sensitivity
of interferometric sensors, but also overcomes the instability of the traditional interferometric sensors, which tend to
being affected from the external environmental condition such as temperature fluctuation. At last, some experimental
curves are presented in this paper.