Radiation treatments have been attracted many interests as one of revolutionary cancer therapies. Today, it is possible to treat cancers without any surgical operations. In the fields of the radiation treatments, it is important to regist the 3D position of the cancer inside the body precisely and instantaneously. To achieve 3D position registrations, we aim at developing a compact camera for 3D measurements. In this trial, we have developed a high-speed pattern projector based on the spatiotemporal conversion technique. In experiments, we show some experimental results for the 3D registrations.
Center alignment is important technique to tune up the spindle of various precision machines in manufacturing industry.
Conventionally such a tool as a dial indicator has been used to adjust and to position the axis by manual operations of a
technical worker. However, it is not easy to precisely control its axis. In this paper, we developed the optical center
alignment technique based on inner profile measurement using a ring beam device. In this case, the center position of the
cylinder hole can be determined from circular profile detected by optical sectioning method using a ring beam device. In
our trials, the resolution of the center position is proved less than 10 micrometers in extreme cases. This technique is
available for practical applications in machine tool industry.
Phase shifting using digital light processing (DLP) projectors enables high-speed three-dimensional (3-D) shape measurements based on a pattern projection method. However, faster phase shifting is required in industry to reduce the measurement time. For this purpose, it is necessary to precisely control the fringe pattern, but conventional DLP projectors afford limited control of the pattern due to their low-refresh rate (typically 120 Hz). Here, a multiwavelength spatiotemporal phase-shifting technique is proposed for faster 3-D shape measurements using a 3CCD camera. The projector consists of a single micro-electro-mechanical system mirror and three laser diodes of different wavelengths. The intensity modulation is transformed from the time to the spatial domain. The phases of the fringe patterns are independently controlled at each wavelength. Images are simultaneously captured of the projected patterns deformed in accord with the surface profile of the objective. The method is validated using a gray code technique for the height measurement of a sample in large steps.
Axially symmetric polarized beams have attracted great interest recently in the field of optics. There have been several viable proposals concerning axially symmetric polarizers, also referred to as radial polarizers. In contrast, proposals for axially symmetric wave plates have strong dependence on wavelength. Moreover, the structure of the axially symmetric wave plates inherently introduces spatial dispersion. As a solution to these problems, we propose an achromatic axially symmetric wave plate based on internal Fresnel reflection that does not introduce spatial dispersion. It is possible to generate the achromatic axially symmetric polarized beam. In this paper, we show the principle of the achromatic axially symmetric wave plate and the evaluation results of the optical element using a Mueller matrix polarimeter.
This paper demonstrated a uni-axial inner profile measurement based on the shape from focus. The key
device is a conical mirror and a variable focus lens. The shape of light beam is transformed from a point
beam to a disk-like beam after passing through the variable focus lens and the conical mirror. The focus
position of the disk-like beam can be controlled by electric current given to the variable focus lens. The
beam is formed like a ring on the inner surface of the cylindrical sample. A CCD camera captures the ring
as intensity distribution after the ring beam turn back to the way. The magnitudes of the intensity
distribution are changed along focused positions of the ring beam. That is to say, the intensity distribution
is described a Gaussian profile in the function of the electric current value. As this result, the radius
distribution of the inner surface profile can be determined from the property of electric current of the
variable focus lens. We have shown some experimental results as a coaxial inner profile measurement.
This paper is not an original paper, but a review paper passed on our previous papers. We have been developing a few
apparatuses for 2D and/or 3D profile measurement because these systems, especially 3D profiling systems, have become
indispensable tools in manufacturing industry. However, in surface profile measurement, conventional systems have
several short comings including being very large in size and heavy in weight. Therefore we propose to realize a compact
portable apparatus on the basis of pattern projection method using a single MEMS mirror scanning. On the other hand, in
the case of inner profile measurement for pipes or tubes, we propose to use optical section method by means of disk
beam produced by a conical mirror. In these systems development of elements and devices such as a MEMS mirror
and/or cone mirror play important role to apply our fundamental principles to practical apparatuses. We introduce the
state of the art of these systems including commercialized products for practical purpose.
The requirements of inner profile measurement of pipes and holes become recently larger and larger, and applications of inner profile measurement have rapidly expanded to medical field as well as industrial fields such as mechanical, automobile and heavy industries. We have proposed measurement method by incorporating a ring beam device that produces a disk beam and have developed various probes for different inner profile measurement. To meet request for applying to smaller diameter pipes,
we tried to improve the ring beam light source using a conical mirror, optical fiber collimator and a laser diode. At this moment a probe with the size of 5 mm in diameter has been realized.
Both optical vortices and polarization vortices (vectorial vortices) are known to have attracted great interest in
the field of optics. Although there have been some proposals concerning axially symmetrical polarizers, also
referred to as radial polarizers, axially symmetrical wave plates (AS-WPs) have not previously been
proposed. Particularly, the AS-WP has strongly dependence on both the wavelength and the temperature.
Moreover, the structure of AS-WPs inherently introduce spatial dispersion. As a solution to these problems,
we have proposed an achromatic axially symmetrical wave plate (AAS-WP) based on Fresnel reflection that
does not introduce spatial dispersion. In this paper, we show the principle of generation, the optical properties
of the optical element, and the generation method of the vortex spectrum for changing the polarization order,
a well-known characteristic in singularity optics Moreover, in this paper, we also describe a generation
technique for a high-order optical vortex based on geometric phase and the interferometric observation of the
topological effect of the proposed AAS-WP.
To overcome inherent problems with conventional three-dimensional profiling systems based on pattern-projection method, we propose incorporating a digital device, such as a single MEMS mirror in the projection optics. In this system, a projector is controlled to generate a projection pattern with an appropriate periodic structure and sinusoidal intensity distribution. The key aspect to this projection method is that sinusoidal signals are generated by a function generator; that is, the temporal sinusoidal intensity distribution is transformed from the time domain to the spatial domain. This flexible pattern-projection method permits phase-shifting techniques to be applied to industrial measurement and inspection. This apparatus is so compact as to have a dimensional size similar to a conventional digital camera [53 mm(H)×130 mm(W)×38 mm(D)]. Furthermore, it is lightweight (320 g) without a battery or circuit boards. Such a compact system can be used as a palm-top camera and potentially may be used in low cost measurement systems for three-dimensional profilometry.
It is one of the important necessities to precisely measure the inner diameter and/or the inner profile of pipes, tubes and
other objects similar in shape. Especially in mechanical engineering field, there are many requests from automobile
industry because the inner surface of engine blocks and other die casts are strongly required to be inspected and
measured by non-contact methods (not by the naked eyes inspection using a borescope). If the inner diameter is large
enough like water pipes or drain pipes, complicated and large equipment may be applicable. However, small pipes with a
diameter ranging from 10mm to 100mm are difficult to be inspected by such a large instrument as is used for sewers
inspection. And we have proposed an instrument which has no moving elements such as a rotating mirror or a prism for
scanning a beam. Our measurement method is based on optical sectioning using triangulation. This optically sectioned
profile of an inner wall of pipe-like objects is analyzed to produce numerical data of inner diameter or profile. Here, we
report recent development of the principle and applications of the optical instrument with a simple and compact
configuration. In addition to profile measurement, we found flaws and defects on the inner wall were also detected by
using the similar principle. Up to now, we have developed probes with the diameter of 8mm to 25mm for small size
objects and another probe (80 mm in diameter) for such a larger container with the dimensional size of 600mm.
Three-dimensional measurement based on a pattern projection method has a lot of requirements such as inspections,
evaluations and designings in the fields of industry. We have proposed a projection technique using a single MEMS
mirror and a laser diode to realize a compact camera for three-dimensional measurement. This projection technique is
able to be transformed the mechanism of the projection from time domain to spatial domain. From this technique, we
achieved to develop a palm-top camera for three-dimensional profile measurement. In this paper, we propose recent
improvement of the principle and its applications. We have developed three-dimensional measurement method based on
a single MEMS mirror using three-color laser diodes and 3CCD camera. The measurement method has combined the
merits of pattern projection method with the merits of gray code technique.
Inner profile measurement is an important matter in such fields as medicine, dentistry and anthropology as well as
mechanical engineering and other industrial applications. Here we describe recent development of our measurement
principle for inner diameter of pipes and/or holes. The key device in this technique is a ring beam device which
consists of a conical mirror and a laser diode. And the fundamental principle is based on optical sectioning without
using any contact type stylus. The optically sectioned profile of an inner wall of a pipe-like object is analyzed to give
the inner profile in addition to the inner diameter. This optical instrument with a simple and small configuration is
now under development for practical uses. In our hitherto trial experimental works, the availability of this instrument
has been evaluated in many cases and availability for practical applications is expected, especially, for measurement
and inspection of mechanical components and elements besides pipes. This ring beam device consisting of a conical
mirror and a LD is assembled to form a disk-like light sheet. We show measurement result of pipes and holes, and, at
the same time, report a compact inner profile measuring instrument at this point. Both the ring beam device and a
miniaturized CCD camera are fabricated into a glass tube. Availability of this instrument is shown by measuring the
inner profiles of various pipes. In response to this trial, there appeared a strong request that not only the internal but
external profiles should be measured simultaneously. Therefore we propose potentially possible method for
measurement of external profile at the same time with internal profile. If one pair of concave mirrors are used in our
arrangement, external profile is captured. In combination with inner profile measurement technique, simultaneous
measurement of inner and outer profiles becomes attainable. A measurement result on a bevel gear shows availability
of here proposed principle. In addition, we are trying to extend our technique to check defects and/or flaws on the
inner wall of pipe-like objects.
In this paper, we have developed a spectroscopic topological Stokes polarimeter using an axisymmetrical quarter wave
plate (AQWP). The AQWP is fabricated by the alignment of segments of quarter wave films. The azimuthal angles of
the polarization element are changed in according with its own segment. This element works as same the technique as
the rotating quarter wave plate. In the experiment, we evaluated birefringence distribution of the AQWP. By changing a
position of polarized singularity point in the beam spot, we can measure states of polarization. We demonstrate that the
change of polarization states is corresponded with the change of the polarized singularity points.
To improve difficulties inherent to the conventional three-dimensional profiling system based on pattern projection
method, we have proposed incorporating a recent digital device such as a MEMS scanner into projection optics. Due to
this revision, first of all, such a small size system as a palm-top camera is attainable, and low cost measurement system is
potentially realized. In this system, we can control the scanner to produce the projection pattern with appropriate
periodical structure and sinusoidal intensity distribution. Due to this flexible pattern projection, phase-shifting technique
becomes applicable for industrial inspection and measurement in automobile industry and others. The camera is as small
as a photographic digital camera in dimensional size. In addition, our recent improvement of measuring performance by
modulating the projected pattern is to be demonstrated.
Inner profile measurement is an important matter in such fields as medicine, dentistry and anthropology as well as
mechanical engineering and industry. Here we propose a measurement method for inner diameter of pipes and/or
holes. The key device in this technique is a ring beam device which consists of a conical mirror and a laser diode.
And the fundamental principle is based on optical sectioning without any contact probe. The optically sectioned
profile of an inner wall of a pipe-like object is analyzed to give the inner profile in addition to the inner diameter.
This optical instrument with a simple and small configuration is now under development for practical uses. In the
hitherto-tried experimental works, the availability of this instrument has been highly evaluated and usability for
practical applications is expected, especially, for measurement and inspection of mechanical components and
elements besides pipes. This ring beam device consisting of a conical mirror and a LD is assembled to form a disklike
light beam sheet. We show measurement result of pipes and holes, and, at the same time, report a compact inner
profile measuring instrument. Both the ring beam device and a miniaturized CCD camera are fabricated in a glass
tube. Availability of this instrument is shown by measuring the inner profiles of various pipes. In response to this
trial, there appeared a strong request that not only the internal but external profiles should be measured
simultaneously. Therefore we propose an improved method for measuring the external profile in addition to the
internal profile. In our arrangement, one pair of concaved conical mirrors is used for the external profile
measurement. In combination with the inner profile measurement technique, simultaneous measurement of the inner
and outer profiles becomes attainable. A measurement result on a bevel gear shows availability of newly proposed
principle. Now we are aiming to realize simultaneous measurement of the internal and external profiles of various
types of pipes and similar objects.
To improve difficulties inherent to the conventional three-dimensional profiling system based on pattern projection
method, we propose incorporating a recent digital device such as a MEMS scanner into projection optics. Due to this
revision, first of all, a compact measurement system is easily attainable, and, when we adjust the scanner to produce the
original pattern with non-equal periodical structure, the projected pattern is so formed as to be equal in period on the
reference plane. In addition, the pattern becomes sharp over the whole field of measurement when the Scheimpflug
condition is satisfied in optical arrangement. This brings easier analysis of the captured pattern and attains the threedimensional
profilometry system with deeper range of focus, wider field of measurement and higher accuracy of
Mueller matrix polarimeter using the axisymmetrical polarized and analyzed optics is proposed. The axisymmetrical
optics has a potential to bring out the polarization properties of a sample which kept in beam spot. A key device of this
method is a detector named "a ring beam detector". The concept of the detector is a topology and/or a projective
transformation and the optical configuration of the detector consists of a conical mirror and/or a conical lens, a
cylindrical screen and a CCD camera. To use a Fourier transform method, we can get Mueller matrix properties from the
intensity distribution of the ring beam captured by the camera without a mechnically and electrically polarization
modulation. In this paper, principles of axisymmetrical Mueller matrix polarimeter, the ring beam detector and basically
experimental results are shown.
An optical driven actuator has a feature of a non-contact for applying light energy remotely. An optical tweezers and a
laser manipulation for small particles are powerful tool for nano-micro bio-technology. Nowadays, a vectorial vortex
attracts the attention of their purpose because it can rotate the particle by polarization. In this paper, we propose a
spatially variant polarized beam called vectorial vortex array for the optical tweezers. A generation mechanism of the
beam consists of phenomena of the polarization made of a radial polarizer and QHQ (quarter wave plate Q and half
wave plate H) and the interference. The vectorial vortex array is converted to different spatially variant polarized beams
by changing geometric phase. Their polarized beams are shown in experimentally.
A ring beam device consisting of a conical mirror and a LD is available to form a disk-like beam sheet. We have shown measurement result of an inner diameter of pipes and holes and have developed a compact inner profile measuring instrument up to now. The ring beam device and a miniature CCD camera are incorporated in a glass tube. Validity of this instrument was shown by checking the inner profile of the references. In response to this trial, there appeared a strong request that not only an internal but also external inspection should be measured. Surely the pattern projection method conventionally used in 3D profile measurement may be useful for high speed and high precision measurement of various objects, but it is not always appropriate to measure an object with steeply inclined surface profile such as a bevel gear. In this paper, we propose a method for measurement of the external profile in addition to the internal profile. In our arrangement, one pair of concaved conical mirrors is used for the external profile measurement. When combined with our inner profile measurement method, simultaneous measurement of the inner and outer profiles becomes possible. A measurement result on a bevel gear showed availability of our proposal. We are aiming to realize simultaneous measurement of the internal and external profiles.
Inner profile measurement has a lot of request for the applications in field of mechanical industry and even in the medical and dental fields. We proposed measurement method of inner diameters of pipes and/or holes using a ring beam device which consists of a conical mirror and a laser diode. This measurement method is based on optical sectioning of inner wall. This optically sectioned profile is analyzed to calculate the inner diameter and/or profile. Here, an optical instrument with a simple and compact configuration is reported for the inner profile measurement. As experimental results, we show performance of the instrument and some examples for inspection of mechanical components.
We propose a compact measurement system for surface profilometry using a MEMS scanner. Beam from a LD is scanned by a miniaturized MEMS mirror
with the size of 4mm×3mm (or 6mm×7mm) produces an optically sectioned line profile of a sample. Hence, if we scan the beam vertically and horizontally by this two-dimensional type of MEMS scanner, the optical sections of the sample object
are formed, and the scanned result can be caught by a CCD camera and stored to be analyzed by a PC. The feature of this MEMS scanner is in that the mirror is magnetically driven at the resonant frequency. Therefore, due to resonance effect, even this small mirror brings a large scanning angle, high-speed scanning, low noise and low power consumption. The miniaturized light-weight design is also applied to realize the compact measurement system. The principle for measurement known as "triangulation" is very simple, but high accuracy is expected thanks to the recent development of sub-pixel technique. At this point of time, we are fabricating a proto-type equipment for the experimental use and, in near future, we will try to attain a compact three-dimensional measurement system using this scanner and a small bright LED light source.
We propose a white light displacement sensor using a novel spectro-polarization modulator which generates spiral liner
polarized light sorted along wavelength concentrically. It consists of a polarizer, a retarder with high order retardation,
and a quarter wave plate. If we set the spiral polarizer after the spectro-polarization modulator, we can observe
spectroscopic color concentrically. A displacement measurement method is proposed using chromatic aberration method
and white light interferometer.
Many trials have been proposed to measure inner diameter of pipes and/or holes. However most of them are classified
into contact methods with any kind of stylus. Here we propose to measure inner diameter and profile of pipes using a ring beam device which consists of a conical mirror. and LD. The beam from the LD is directed to the top of the conical mirror which is precisely fabricated in angle and polished so as to form a ring beam for optical sections of the inner wall. This optically sectioned profile is analyzed to calculate the inner diameter and/or profile. In addition to pipes such as water mains and sewers, engine blocks for automobiles are tested to measure the inner size of cylinders and to find defects of inner surfaces.
We propose a novel spectro-polarization modulator which generates radial liner polarized light sorted along wavelength
concentrically. It consists of a polarizer, a retarder with high order retardation, and a quarter wave plate. If we set the
radial polarizer after the spectro-polarization modulator, we can observe spectroscopic color concentrically. A
displacement measurement method is proposed using chromatic aberration method.
A measurement method for birefringence dispersion is proposed using geometric phase. The optical arrangement consists of a white light source, polarizer, sample, quarter-wave plate, rotating analyzer, such as in a Senarmont setup, and a spectrometer for the visible spectrum from 450 to 750 nm. The experimental setup achieves a phase shift via the geometric phase produced by a cyclic change of polarization state on a Poincaré sphere. We can select four points of geometric phase when the analyzer is set at –45, 0, 45, and 90 deg. It is mathematically demonstrated that these points of geometric phase are independent of wavelength from the calculation of spherical trigonometry drawn on the Poincaré sphere. The phase shifting technique using these four geometric phases is applied to measure birefringence dispersion. Polymer films and optical crystals as samples are experimentally demonstrated, and it is shown that the experimental results agree well with the known quantities of retardation in the visible spectrum.
This paper describes a method and system for the measuring the two-dimensional distribution of birefringence dispersion. An optical arrangement consists of a white light source, parallel polarizers, a CCD camera, and an acousto-optic tunable filter for selecting wavelength of the incident light. The intensity of spectroscopic polarized light changes sinusoidally as a function of wave number, and its period changes slightly because of birefringence dispersion. The fast Fourier transform method is used to analyze the birefringence dispersion from the spectroscopic polarized light. One hundred twenty-eight captured images are used for the analysis. Some experimental results on 2-D birefringence dispersion distributions are shown for the demonstration of this method.
A real-time measurement method for both birefringence dispersion and azimuthal angle is described. An optical set-up of this measurement consists of a white light source, two polarizers and two reterders without any rotation. A spectroscopic intensity is detected by a spectrometer. It is modulated with two different frequencies along wave number. Only the single spectroscopic intensity is sufficient to determine the retardation and the azimuthal angle with wavelength-dependence using two amplitude spectrum and phase by the fast Fourier transform method. A birefringence measurement of a Babinet-Soleil compensator as a sample is demonstrated experimentally.
A measurement method of birefringence dispersion by geometric phase is described. The measurement system consists of a polarizer, a quarter wave plate, a rotating analyzer and a spectrometer. The detected intensity by a spectrometer changes sinusoidaly along wave number. A phase shifting method is applied to analyze birefringence dispersion. The total amounts of phase change in all of wavelengths are same, because geometric phase produces by cyclic changes of a state of polarization on the Poincaré sphere. The birefringence dispersion of Babinet-Soleil compensator, polymer films and a liquid crystal phase modulator is measured. Compared measured these results with literature values of birefringence dispersion, measured data agrees well. The measurement results shown the birefringence dispersion measurement by geometric phase is available to practical applications.
This paper describes a method and system for two-dimensional measurement of birefringence dispersion with high-order and azimuthal direction. The system consists of a white light source, crossed polarizers and a detector carrying out the spectroscopic polarized light. A spectroscopic interferogram shows sinusoidaly in accordance with wave number change, and its period changes slightly because of dispersion of birefringence. The fast Fourier transform method is used to analyze the birefringence from the spectroscopic interferogram. One hundred and twenty-eight sets of images are used for birefringence analysis. Some results of 2-D birefringence dispersion distribution are shown for the demonstration of this method.
This paper describes a method and device for measurement of two-dimensional retardance and dispersion with high-order and azimuthal direction. The system consists of a white light source, crossed polarizers and a detector for spectroscopic polarized light. A spectroscopic interferogram shows sinusoidal to wave number change, and its period changes slightly because of dispersion of birefringence. Fourier transform method is used to analyze the birefringence from the spectroscopic interferogram. One hundred and twenty-eight sets of images are used for birefringence analysis. Some results of 2D birefringence distribution with dispersion are shown for the demonstration.