SCOTS (software configurable optical test system) is a useful tool that can provide lens manufacturers with the ability to
evaluate the net performance of a lens system without the use of complex metrology systems and setups. This technique
is based on measuring the transverse ray aberrations of rays to obtain wavefront information using transmission
deflectometry, the refractive equivalent of reflection deflectometry.
Some work using deflectometry on refractive surfaces has been briefly reported in the past, where the power of a single
lens has been the measurement objective. Results showing the use of deflectometry on reflective optical surfaces, such
as the primary mirror of the Giant Magellan Telescope (GMT) show that this method has a large dynamic range in
which measurement accuracy is comparable with those of interferometric methods; generating interest on our part, to
investigate deflectometry for refractive systems in more detail.
In this paper, we focus on reporting initial tests using SCOTS by measuring simple refractive elements, such as 1"
diameter biconvex BK7 lenses. Results indicate a good agreement when comparing them with equivalent
MATLAB/ZEMAX wavefront measuring models, which include the measured lens parameters, where the estimated and
measured wavefront RMS values and spherical aberration Zernike coefficient agree on average to within 10nm. We also
investigate the effect of the chromatic aberration on the refractive optical system by collecting data using three different
wavelengths: 620nm, 550nm and 450nm. The alignment of the test setup was done rapidly and we used an LCD screen
with a pixel pitch of 0.1905mm. The camera used for the measurements was a simple digital CCD camera.
SCOTS (software configurable optical test system) is a useful tool that can provide lens manufacturers with the ability to
evaluate the net performance of a lens system without the use of complex metrology systems and setups. This technique
is based on measuring the transverse ray aberrations of rays to obtain wavefront information using transmission
deflectometry, the refractive equivalent of reflection deflectometry.
Some work using deflectometry on refractive surfaces has been briefly reported in the past, where the power of a single
lens has been the measurement objective. Results showing the use of deflectometry on reflective optical surfaces, such
as the primary mirror of the Giant Magellan Telescope (GMT) show that this method has a large dynamic range in
which measurement accuracy is comparable with those of interferometric methods; generating interest on our part, to
investigate deflectometry for refractive systems in more detail.
In this paper, we focus on reporting initial tests using SCOTS by measuring simple refractive elements, such as 1"
diameter biconvex BK7 lenses. Results indicate a good agreement when comparing them with equivalent
MATLAB/ZEMAX wavefront measuring models, which include the measured lens parameters, where the estimated and
measured wavefront RMS values and spherical aberration Zernike coefficient agree on average to within 10nm. We also
investigate the effect of the chromatic aberration on the refractive optical system by collecting data using three different
wavelengths: 620nm, 550nm and 450nm. The alignment of the test setup was done rapidly and we used an LCD screen
with a pixel pitch of 0.1905mm. The camera used for the measurements was a simple digital CCD camera.
Software Configurable Optical Test System (SCOTS)[1], a computerized "reverse Hartmann test", can rapidly, robustly
and quantitatively measure complex 3-dimensional specular surfaces, for instance large segmented solar collectors,
faceted automotive headlight reflector or other free-form surfaces.
We propose two parameters CS and AS for fast estimating sensitivities to constant coma and linear astigmatism in a
misaligned lens system. We show that these figures correlate well with actual tolerancing of some lens systems.
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.
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.
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.
This past spring a new for-credit course on illumination engineering was offered at the College of Optical Sciences at
The University of Arizona. This course was project based such that the students could take a concept to conclusion. The
main goal of the course was to learn how to use optical design and analysis software while applying principles of optics
to the design of their optical systems. Projects included source modeling, displays, daylighting, light pollution, faceted
reflectors, and stray light analysis. In conjunction with the course was a weekly lecture that provided information about
various aspects of the field of illumination, including units, étendue, optimization, solid-state lighting, tolerancing, litappearance
modeling, and fabrication of optics. These lectures harped on the important points of conservation of
étendue, source modeling and tolerancing, and that no optic can be made perfectly. Based on student reviews, future
versions of this course will include more hands-on demos of illumination components and assignments.
Faceted reflectors are widely used for providing uniform illumination in many commercial lighting products. In this
paper, some approaches of constructing faceted reflectors in commercial software are discussed. Two new methods for
generating non-rotationally symmetric patterns such as square/rectangular illumination patterns using curved-faceted
reflectors are proposed and also explored in commercial software. The performances of various reflectors are compared
using Monte Carlo ray-tracing.
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