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- Front Matter: Volume 9771
- Materials and Processes
- Holography, Art and Perception
- Applications I
- Applications II
- Digital Holography I
- Digital Holography II
- Poster Session
Front Matter: Volume 9771
Front Matter: Volume 9771
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This PDF file contains the front matter associated with SPIE Proceedings Volume 9771, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.
Materials and Processes
Single-beam Denisyuk holograms recording with pulsed 30Hz RGB laser
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It is well known fact that holograms can be recorded either by continuous wave (CW) laser, or by single pulse coming from pulsed laser. However, multi-pulse or multiple-exposure holograms were used only in interferometry as well as for information storage. We have used Geola's single longitudinal mode pulsed RGB laser to record Denisyuk type holograms. We successfully recorded objects situated at the distance of more than 30cm, employing the multi-pulse working regime of the laser. To record Denisyuk hologram we have used 50 ns duration 440, 660nm wavelength and 35ns duration 532nm wavelength laser pulses at the repetition rate of 30Hz. As photosensitive medium we have used Slavich-Geola PFG-03C glass photoplate. Radiations with different wavelengths were mixed into "white" beam, collimated and directed onto the photoplate. For further objects illumination an additional flat silver coated mirror was used.
Precision holographic optical elements in Bayfol HX photopolymer
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The versatility of Volume Holographic Optical Elements (vHOE) is high, especially because of their tunable angular and
spectral Bragg selectivity. Those unique lightweight, thin and flat optical elements are enabled by the new instant
developing photopolymer film Bayfol® HX technology, which allows to mass produce cost effective diffractive optics
due to its simplified and robust holographic recording process.
From a pure scientific point of view volume holography is well established. In practice though, commercially available
optical design software is not adapted to handle the specific characteristics of photopolymer diffractive optical elements
and their recording. To achieve high quality vHOE precision optics, the recording setup needs to accommodate several
aspects that will be covered in this paper. We report on means how to deal with photopolymer shrinkage and average
refractive index changes of the recording media. An important part in diffractive optics design is the compensation of
different conditions between the holographic recording setup and in a final product containing the vHOE. Usually
substrates might need to be changed (in material, in refractive index) as well the illumination sources are using
incoherent light having angular and spectral emission profiles with finite bandwidth.
Recently special in- and out-coupling vHOEs are becoming attractive e.g. in near eye displays and in compact lighting
devices. We will report on design considerations and adjustments to the recording condition for a specific in-coupling
vHOE and demonstrate the effects of pre-compensation on this example.
Holography, Art and Perception
Ultra-realistic imaging and OptoClones
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Recent improvements in solid state CW lasers, recording materials and light sources (such as LED lights) for displaying
color holograms are described. Full-color analogue holograms can now be created with substantially better image
characteristics than previously possible. To record ultra-realistic images depends on selecting the optimal recording laser
wavelengths and employing ultra-fine-grain, silver-halide materials. The image quality is improved by using LED
display light with improved spatial coherence. Recording museum artifacts using mobile holographic equipment is
described. The most recent recorded such holograms (referred to as OptoClones™) are the Fabergé Eggs at the Fabergé
Museum in St. Petersburg, Russia.
Concurrent studies on artworks by digital speckle pattern interferometry and thermographic analysis
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We utilize Digital Speckle Pattern Interferometry and Square Pulse Thermography Analysis, as complementary tools for
cultural heritage artifacts diagnostics. The concurrent utilization of two methods provide the possibility to complement
and validate the effective understanding of each individual technique results, that are not always easy to interpret. Both
techniques are non-invasive and can be applied on almost any type of archaeological finds, providing relevant
information about their state of conservation. The applications include the whole structure analysis, as well as the
detection of detachments, micro-cracks, hidden damages. The diagnostic investigation can be carried out before, during
and after a restoration. It is also possible the real time monitoring of the behavior of the object according to the
environment thermo-hygrometric changes. Examples of analysis on different artworks are illustrated.
Silent images in dialogue
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In this series of digital art holograms and lenticulars, we used the HoloCam Portable Light System with the 35 mm cameras, Canon IS3 and the Canon 700D, to capture the image information, it was then edited on the computer using Motion 5 and Final Cut Pro X programs. We are presenting several actions in the digital holographic space. The figures are in dialogue within the holographic space and the viewer, in front of the holographic plate. In holography the time of the image is the time of the viewer present. And that particular feature is what distinguishes digital holography from other media.
Applications I
Development of 3D holographic endoscope
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Here we present the development of a 3D holographic endoscope with an interferometer built around a commercial
rigid endoscope. We consider recording the holograms with coherent and incoherent light separately without
compromising the white light imaging capacity of the endoscope. In coherent light based recording, reference
wave required for the hologram is obtained in two different ways. First, as in the classical holography, splitting the
laser beam before the object illumination, and secondly creating the reference beam from the object beam itself.
This second method does not require path-length matching between the object wave and the reference wave,
and it allows the usage of short coherence length light sources. For incoherent light based holographic recordings
various interferometric configurations are considered. Experimental results on both illumination conditions are
presented.
Virtual interferogram-generation algorithm for phase measurement using two interferograms
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Phase-shifting digital holography is a technique for phase measurement with high spatial resolution and applied to many
fields. This technique typically requires four phase-shifted interferograms between a signal beam and a reference beam.
We focused on the two-step phase shifting algorithm, which needs only two phase-shifted interferograms and an
intensity distribution of the reference beam to reduce the number of required interferograms. However, in this algorithm,
the intensity of the reference beam must be much greater than that of the signal beam because this algorithm uses the
quadratic formula and the inside of square root must be positive. This leads to the saturation of the dynamic range of the
image sensor and the degradation of accuracy. In this paper, we propose a virtual interferogram-generation algorithm
(VIGA) to improve the performance of phase-shifting digital holography only using two interferograms. This algorithm
virtually generates a π phase-shifted interferogram by the intensity distribution of the signal beam and that of the
reference beam with an observed interferogram. Therefore, capturing two real interferograms and generating two virtual
interferograms, the four-step phase shifting algorithm can be used for this method. Comparing to the conventional
algorithm, the VIGA has no limitation in terms of the magnitude of the intensity. This means that the intensity of the
reference beam and that of the signal beam can be equalized and the dynamic range saturation of the image sensors can
be prevented. Therefore, the VIGA makes highly accurate phase measurement possible owing to the effective utilization
of the dynamic range of the image sensors.
Applications II
Holographic topography using acousto-optically generated large synthetic wavelengths
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Digital holography uses phase imaging in a variety of techniques to produce a three-dimensional phase
resolved image that includes accurate depth information about the object of interest. Multi-wavelength digital
holography is an accurate method for measuring the topography of surfaces. Typically, the object phases are
reconstructed for two wavelengths separately and the phase corresponding to the synthetic wavelength (obtained
from the two wavelengths) is obtained by calculating the phase difference. Then the surface map can be obtained
using proper phase-unwrapping techniques. Usually these synthetic wavelengths are on the order of microns which
can be used to resolve depths on the order of microns. In this work, two extremely close wavelengths generated
by an acousto-optic modulator (AOM) are used to perform two-wavelength digital holography. Since the
difference between the two wavelengths is on the order of picometers, a large synthetic wavelength (on the order
of centimeters) can be obtained which can be used to determine the topography of macroscopic surface features.
Also since the synthetic wavelength is large, an accurate surface map can be obtained without using a phase-unwrapping
technique. A 514 nm Argon-ion laser is used as the optical source, and used with an AOM to generate
the zeroth-order and frequency-shifted first-order diffracted orders which are used as the two wavelengths. Both
beams are aligned through the same spatial filter assembly. Holograms are captured sequentially using a typical
Mach-Zehnder interferometric setup by blocking one beam at a time. Limitations of the large synthetic wavelength
are also discussed.
Enhancing phase retrieval speed for real-time interferometer and ESPI by two-dimensional continuous wavelet transform
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A real-time three-dimensional surface profile metrology system was implemented by integrating Fourier
Transform (FT) based algorithms to convert interference intensity fringes to wrapped frequency phase maps and then to
unwrapped phase maps. The revival of this field can find its roots in recognizing the development of high-resolution high-speed
CCD/CMOS over the years. Two-dimensional Continuous Wavelet Transform (2D-CWT), which possesses the
ability to construct daughter wavelets of good time and frequency localization according to different fringes conditions
from a characteristic mother wavelet, was implemented with an attempt to reduce redundant fitting process of ordinary
Short Time Fourier Transform (STFT), also known as Windowed Fourier Transform (WFT), and therefore to accelerate
the FT-related algorithms needed. Implemented with the efficient wavelet construction process by using 2D-CWT,
Electronic Speckle Pattern Interferometer (ESPI) was adopted to take advantage of this new process.
Different from using several phase shifting steps before to solve the direction ambiguity, which takes time to
capture multiple intensity maps during measurement, the phase maps needed were retrieved from a single frame
interference fringes. It is to be noted that this one-image interference fringe was captured by having a pre-introduced spatial
carrier frequency embedded within the experimental setup so as to remove the directional ambiguity. 2D-CWT dealing
with different signal-to-noise ratios was also designed by selecting wavelet parameters properly, which is expected to
achieve higher accuracy and faster processing speed. For phase unwrapping, Poisson’s equation with Neumann boundary
condition was solved by using FFT. The benefit of using 2D-CWTs with different wavelets as compared to WFT was
demonstrated experimentally.
Holographic storage system based on digital holography for recording a phase data page in a compact optical setup
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A holographic storage system based on digital holography is proposed for recording and retrieving a phase data
page in a compact and simple optical setup. In the proposed recording system, complex amplitude distribution
can be modulated using a single phase-only spatial light modulator. The complex amplitude distribution of a
retrieved phase data page is detected with the Fourier fringe analysis. The use of digital holographic techniques
enables realizing a compact and simple holographic recording system, which is independent of misalignment problem
in conventional holographic storage systems. The capability of the proposed recording system is numerically
and experimentally evaluated.
Holographic imaging through a scattering medium by diffuser-assisted statistical averaging
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The ability to image through a scattering or diffusive medium such as tissue or hazy atmosphere is a goal which has
garnered extensive attention from the scientific community. Existing imaging methods in this field make use of phase
conjugation, time of flight, iterative wave-front shaping or statistical averaging approaches, which tend to be either time
consuming or complicated to implement. We introduce a novel and practical way of statistical averaging which makes
use of a rotating ground glass diffuser to nullify the adverse effects caused by speckle introduced by a first static diffuser
/ aberrator. This is a Fourier transform-based, holographic approach which demonstrates the ability to recover detailed
images and shows promise for further remarkable improvement. The present experiments were performed with 2D flat
images, but this method could be easily adapted for recovery of 3D extended object information. The simplicity of the
approach makes it fast, reliable, and potentially scalable as a portable technology. Since imaging through a diffuser has
direct applications in biomedicine and defense technologies this method may augment advanced imaging capabilities in
many fields.
Common-path depth-filtered digital holography for high resolution imaging of buried semiconductor structures
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We investigate digital holographic microscopy (DHM) in reflection geometry for non-destructive 3D imaging of semiconductor devices. This technique provides high resolution information of the inner structure of a sample while maintaining its integrity. To illustrate the performance of the DHM, we use our setup to localize the precise spots for laser fault injection, in the security related field of side-channel attacks. While digital holographic microscopy techniques easily offer high resolution phase images of surface structures in reflection geometry, they are typically incapable to provide high quality phase images of buried structures due to the interference of reflected waves from different interfaces inside the structure. Our setup includes a sCMOS camera for image capture, arranged in a common-path interferometer to provide very high phase stability. As a proof of principle, we show sample images of the inner structure of a modern microcontroller. Finally, we compare our holographic method to classic optical beam induced current (OBIC) imaging to demonstrate its benefits.
Investigation of particles located in the water by digital holography
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An automatic technique for processing holograms of particles present in water is proposed. Its applications to determine particle concentration and their size distribution are illustrated with examples. The method is validated using waterborne air bubbles and particles settling in water. The use of video based on holographic data is considered for dynamic investigation of these particles. This video consists of sequences of holographic images of particles and the concentration and particle size distribution is studied in dynamics.
Digital Holography I
Gaze contingent hologram synthesis for holographic head-mounted display
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Development of display and its related technologies provides immersive visual experience with head-mounted-display
(HMD). However, most available HMDs provide 3D perception only by stereopsis, lack of accommodation depth cues.
Recently, holographic HMD (HHMD) arises as one viable option to resolve this problem because hologram is known to
provide full set of depth cues including accommodation. Moreover, by virtue of increasing computational power,
hologram synthesis from 3D object represented by point cloud can be calculated in real time even with rigorous
Rayleigh-Sommerfeld diffraction formula. However, in HMD, rapid gaze change of the user requires much faster refresh
rate, which means that much faster hologram synthesis is indispensable in HHMD. Because the visual acuity falls off in
the visual periphery, we propose here to accelerate synthesizing hologram by differentiating density of point cloud
projected on the screen. We classify the screen into multiple layers which are concentric circles with different radii,
where the center is aligned with gaze of user. Layer with smaller radius is closer to the region of interest, hence, assigned
with higher density of point cloud. Because the computation time is directly related to the number of points in point
cloud, we can accelerate synthesizing hologram by lowering density of point cloud in the visual periphery. Cognitive
study reveals that user cannot discriminate those degradation in the visual periphery if the parameters are properly
designed. Prototype HHMD system will be provided for verifying the feasibility of our method, and detailed design
scheme will be discussed.
Progress in off-plane computer-generated waveguide holography for near-to-eye 3D display
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Waveguide holography refers to the use of holographic techniques for the control of guided-wave light in integrated optical
devices (e.g., off-plane grating couplers and in-plane distributed Bragg gratings for guided-wave optical filtering).
Off-plane computer-generated waveguide holography (CGWH) has also been employed in the generation of simple field
distributions for image display. We have previously depicted the design and fabrication of a binary-phase CGWH operating
in the Raman-Nath regime for the purposes of near-to-eye 3-D display and as a precursor to a dynamic, transparent
flat-panel guided-wave holographic video display. In this paper, we describe design algorithms and fabrication techniques
for multilevel phase CGWHs for near-to-eye 3-D display.
Filling factor characteristics of masking phase-only hologram on the quality of reconstructed images
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The present study evaluates the filling factor characteristics of masking phase-only hologram on its corresponding
reconstructed image. A square aperture with different filling factor is added on the phase-only hologram of the target
image, and average cross-section intensity profile of the reconstructed image is obtained and deconvolved with that of
the target image to calculate the point spread function (PSF) of the image. Meanwhile, Lena image is used as the target
image and evaluated by metrics RMSE and SSIM to assess the quality of reconstructed image. The results show that the
PSF of the image agrees with the PSF of the Fourier transform of the mask, and as the filling factor of the mask
decreases, the width of PSF increases and the quality of reconstructed image drops. These characteristics could be used
in practical situations where phase-only hologram is confined or need to be sliced or tiled.
Digital Holography II
Image quality evaluation and control of computer-generated holograms
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Image quality of the computer-generated holograms are usually evaluated subjectively. For example, the re- constructed image from the hologram is compared with other holograms, or evaluated by the double-stimulus impairment scale method to compare with the original image. This paper proposes an objective image quality evaluation of a computer-generated hologram by evaluating both diffraction efficiency and peak signal-to-noise ratio. Theory and numerical experimental results are shown on Fourier transform transmission hologram of both amplitude and phase modulation. Results without the optimized random phase show that the amplitude transmission hologram gives better peak signal-to noise ratio, but the phase transmission hologram provides about 10 times higher diffraction efficiency to the amplitude type. As an optimized phase hologram, Kinoform is evaluated. In addition, we investigate to control image quality by non-linear operation.
Efficient calculation method for realistic deep 3D scene hologram using orthographic projection
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We propose a fast calculation method to synthesize a computer-generated hologram (CGH) of realistic deep three-dimensional
(3D) scene. In our previous study, we have proposed a calculation method of CGH for reproducing such scene
called ray-sampling-plane (RSP) method, in which light-ray information of a scene is converted to wavefront, and the
wavefront is numerically propagated based on diffraction theory. In this paper, we introduce orthographic projection to the
RSP method for accelerating calculation time. By numerical experiments, we verified the accelerated calculation with the
ratio of 28-times compared to the conventional RSP method. The calculated CGH was fabricated by the printing system
using laser lithography and demonstrated deep 3D image reconstruction in 52mm×52mm with realistic appearance effect
such as gloss and translucent effect.
Poster Session
Study of gratings with variable periods
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A theoretical study with sinusoidal amplitude diffraction gratings, elaborated with variable periods is shown. The diffraction pattern behavior and the symmetry degree of the gratings were observed. The grating period is increased, fringe to fringe, starting with a small period and ending with a big period that is; the grating edge, start with high spatial frequency and finish with low spatial frequency. This gratings modulation causes a widening in the diffracted orders.
Holographic cells with random distribution and determined orientation
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Study of diffraction gratings through holographic cells, which correspond to micro circular zones, encoded with amplitude sinusoidal gratings. The random distribution of cells on the surface of hologram and its orientation of gratings per cell, produce in the diffracted orders a random distribution. We made a study of the behavior of the random modulation of diffracted orders, as a function of the orientation of code grating per cell.
Holographic recording physicochemical mechanism for PVA-FeCl3 + h[nu]
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Photo-physicochemical processes involved in the images recording are described. A holographic grating in recording process generates photo-crosslinking through electron transfer, by the active and not active radical mobility ions in the system [PVA + FeCl3 + H2O + hv]. The electric charges reorientation by the polarity between atoms and molecules establish intramolecular crosslinks. This process is essential due to the photochemical reaction for reducing Fe3+ to Fe2+ ion. The optimal holographic film shows diffraction efficiency the order of 26%.
Dynamic gratings recording in liquid crystal light valve with semiconductor substrate
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Liquid crystal light valve with GaAs substrate operating in the transmission mode in the infrared is studied. The
nonlinear phase shift of the transmitted light wave is measured as a function of applied voltage. The dynamic grating
recording is achieved. A fourfold amplification of the weak signal beam is reached. The gain is increased by means of
proper tilting of the cell that increases an effective pretilt of the liquid crystal molecules. The amplitude of the refractive
index modulation and nonlinear coupling constant are estimated from the experimental results.
Preparation and characterization hexoses for holographic recording
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Experimental technique is described for holographic record in two different hexoses, with a new photosensitizer, the
ferric ammonium citrate, and compared to the hexoses-dichromated films. The ferric ammonium citrate is an optimal salt
for photosensitization of hexoses because we obtained a diffraction efficiency to first order acceptable for saccharides
materials (two and three percent), has ability for to storage information, holographic images are quite stable over time, it
is hydrophobic and is cheap. The experiments showed that the films called hexose 1-citrate and hexose 1-dichromate,
present the maximum diffraction efficiency at first diffraction order.
Imaging polarimetry for phase change measurements of the cellophane film
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It is well known that cellophane film has good behavior as half wave retarder for wide spectrum, so, in this
work, we present imaging polarimetry method to measure the phase change introduced by a cellophane film at several
wavelengths in the visible range. The method is achieved when we introduce the cellophane film in a simple optical
arrangement composed by linear polarizers. The phase change of the film is obtained as function of the light intensities at
the output of the system.
Measurement of optical activity of honey bee
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Optical activity of some substances, such as chiral molecules, often exhibits circular birefringence. Circular
birefringence causes rotation of the vibration plane of the plane polarized light as it passes through the substance. In this
work we present optical characterization of honey as function of the optical activity when it is placed in a polariscope that
consists of a light source and properly arranged polarizing elements.
Optical design of cipher block chaining (CBC) encryption mode by using digital holography
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We propose an optical design of cipher block chaining (CBC) encryption by using digital holographic technique,
which has higher security than the conventional electronic method because of the analog-type randomized cipher text
with 2-D array. In this paper, an optical design of CBC encryption mode is implemented by 2-step quadrature phase-shifting
digital holographic encryption technique using orthogonal polarization. A block of plain text is encrypted with
the encryption key by applying 2-step phase-shifting digital holography, and it is changed into cipher text blocks which
are digital holograms. These ciphered digital holograms with the encrypted information are Fourier transform holograms
and are recorded on CCDs with 256 gray levels quantized intensities. The decryption is computed by these encrypted
digital holograms of cipher texts, the same encryption key and the previous cipher text. Results of computer simulations
are presented to verify that the proposed method shows the feasibility in the high secure CBC encryption system.
Diffraction efficiency as function of temperature of holographic gratings into polyvinyl acetate as material holographic replication
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The variation of diffraction efficiency as function of temperature of holographic gratings into polyvinyl acetate
(adhesive) is presented, this material exhibits excellent properties such as transparency, consistency and easy to handle.
The diffraction holographic grating master is copied into polyvinyl acetate film by direct contact and subsequent
exposed at different temperature. The measurements of the diffraction efficiency have been determined by the ratio of
the power of the diffracted light beam to the incident power of the beam.
3D fingerprint analysis using transmission-mode multi-wavelength digital holographic topography
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The analysis of fingerprints is important for biometric identification. Two-wavelength digital holographic
interferometry is used to study the topography of various types of fingerprints. This topography depends on
several conditions such as the temperature, time of the day, and the proportions of eccrine and sebaceous sweat.
With two-wavelength holographic interferometry, surface information can be measured with a better accuracy
compared to single-wavelength phase-retrieving techniques. Latent fingerprints on transparent glass, a
forensically relevant substrate are first developed by the deposition of 50–1000-nm-thick columnar thin films,
and then analyzed using the transmission-mode two-wavelength digital holographic technique. In this technique,
a tunable Argon-ion laser (457.9 nm to 514.5 nm) is used and holograms are recorded on a CCD camera
sequentially for several sets of two wavelengths. Then the phase is reconstructed for each wavelength, and the
phase difference which corresponds to the synthetic wavelength (4 μm to 48 μm) is calculated. Finally, the
topography is obtained by applying proper phase-unwrapping techniques to the phase difference. Interferometric
setups that utilize light reflected from the surface of interest have several disadvantages such as the effect of
multiple reflections as well as the effects of the tilt of the object and its shadow (for the Mach-Zehnder
configuration). To overcome these drawbacks, digital holograms of fingerprints in a transmission geometry are
used. An approximately in-line geometry employing a slightly tilted reference beam to facilitate separation of
various diffraction orders during holographic reconstruction is employed.