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.
This paper describes a grating projection method using phase shifting technique for the measurement of surface profiles of three dimensional objects. In this kind of profilometry a grating with binary intensity distribution has been utilized in most of cases. And in these cases such problems are known as an error is caused due to the non-sinusoidal intensity distribution of the grating and another difficulty is also indicated that the period of the grating is required to be adjusted in accordance with the size and profile of the specimen. Here we propose to use a moire pattern which is produced by superposing two binary gratings. When two gratings are overlapped with an appropriate gap, the resultant moire pattern becomes closely sinusoidal in intensity distribution. Then, in the optical arrangement for profile measurement using a grating projection method, if one grating is rotated, the period of the pattern is varied arbitrarily. And if one or two of the gratings are moved in one direction, the formed moire pattern can be moved in one way to give necessary shifting of the phase. Surface profiles of some samples are measured to show validity of the moire pattern projection and utility of the prototype system.
Recently, various investigations have been carried out using grating projection method based on triangulation. It has advantages such as simple optical arrangement and full-field measurement with high accuracy, and moreover measurement time is shorter compared with other methods like point and/or line scanning. However, it has such
problems as occlusion and phase error due to halation. The first problem is inevitable due to principle of triangulation. The second problem is caused mainly by unequal surface reflectivity of the BGA, CSP and solder bumps, etc. Therefore we propose dual projection method to solve these problems. This proposal consists of one camera and dual projection units with specified liquid crystal gratings. These problems can be avoided owing to measurement from two directions. Finally, three-dimensional profiles are obtained by combining these two results. We intend to present a method that can
extend the use of fringe projection method based on triangulation. In addition to the principle of this system, BGA sample applications are to be shown up.
Non-contact displacement measurement is one of important topics to analyze materials strength and structural deformation. In addition to the industrial applications in mechanical engineering, some research works in such fields as medical and dental fields, life science, textile industry, and even in cosmetics industry require non-contact methods for their specified research areas. Here we propose that both displacement of surface points and profile of an objective are able to be captured by processing textured random pattern on the surface and projected fringe pattern onto the sample. A few potentiall applications to dental and cosmetics fields using our proposal are included.
This paper describes a device for 3D profile measurement systems which are based on grating projection method using phase shifting technique. As a key component to these systems, we propose to apply a liquid crystal (LC) grating instead of a conventional ruled grating which has difficulty in speedy and accurate shifting of the projected pattern. This LC grating consists of 960 lines of stripe pattern on the substrate of 60×40 mm2 in size and has such features as 8 bits of gray levels in dynamic range in mono-chromatic usage. A sinusoidal pattern as well as a binary pattern is realized by combining pulse width modulation control (PWMC) and frame ratio control (FRC) technique. The period of the pattern is arbitrarily controlled and, in addition, shifting of the projected pattern is also electrically realized. We demonstrate a few examples measured by the system which has this LC grating built in.
This paper describes a device for 3D profile measurement systems, which are based on grating projection method using phase shifting technique for fringe analysis. As a key component of these systems, we propose to apply a liquid crystal (LC) grating instead of a conventional ruled grating, which has difficulty in speedy and accurate shifting of the projected pattern. This LC grating consists of 960 lines of stripe pattern on the substrate of 60×40 mm2 in size and has such features as 8 bits of gray levels in dynamic range in use of mono-chromatic applications. A sinusoidal pattern as well as a binary pattern in realized by combining pulse width modulation control and frame ratio control technqiue. In addition, the period of the pattern is arbitrarily controlled and shifting of the projected pattern is also electrically realized. We demonstrate a few examples measured by the system which uses this LC grating inside.
Specular objects with large shape-change such as the concave-shaped mirror are used in the several industrial fields. However, concave-shaped mirror is difficult to measure the surface profile with non-contact method. In this paper, we describe the profile measurement method for concave-shaped mirror such as an ellipsoidal mirror and an aspherical mirror. This measurement method, based on the grating projection method, employed two cylinder-type gratings with different radius; measurement time is shorter than that of contact-method. The surface of ellipsoidal mirror, one of the concave-shaped mirrors, is measured and repeatability accuracy is evaluated.
Optically driven small machines have such features as easily miniaturized in fabricaiont and as controlled by optical energy which is supplied in wireless. We reported an optically controled machine which moves like a caterpillar on the basis of photo-thermal effect. It constis of two parts; a body and feet. The feet can stick to the floor due to magnetic force and therefore it has such ability as ascending a slope, and ultimately it succeeded in climbing the vertical wall and moved underneath the ceiliing. A lot of applications are expected to this kind of machine. However, if the prupose is restircted to the movement inside the pipe, the structure can be more simplified. This time we propose a miniaturized machine which moves like a mole or an earthworm. It mainly consists of a shape-memory alloy and a spring, and nylon wires are attacehd at the head and tail. When the machine moves in the pipe, these wires cause difference in friction force bewteen the forward movement and the backward movement. Stretching and contracting are brought by photon-thermal effect of the body part constising of the alloy and spring. This machine is placed in a vinyl tube and controled by a light beam outside from a halogen lamp. In room tempertuare the alloy is kept stretched by the spring, but when the beam is projected ontothe body from outside, it contracts to the original size becasue photo-thermal effect brings much larger force than the stretching force due to the spring. Then the wires at the head prevent moving back and the wires at the tail easily slip. This fact brings forward movement of the machine. At this moment 25 seconds are necessary for one cycle of movement and the moving speed is 2.6 mm/cycle.
This paper proposes a grating projection method to measure three-dimensional profile of specular objects. This method is principally available for any reflective objects without limitation of sizes. A deformed grating pattern is observed when the reference grating is projected onto a mirror-like surface of object. This deformed pattern reflected from the surface is captured with a CCE camera and analyzed to get three-dimensional profile of the specimen. Experimental results are shown with different samples.
This paper describes a structured lighting method for the measurement of surface profiles of mat objects. In this kind of profilometry, a grating with binary transmittance distribution has been utilized. In these cases such a problem is known that an error is caused due to the non- sinusoidal transmittance of the grating. Another practical difficulty is in mechanical shifting of the grating. Here we propose to use a hybrid grating which consists of a conventional binary grating and a liquid crystal (LC) binary grating. Moire pattern produced by superposing these two binary gratings is available to overcome these problems. When two binary gratings are overlapped, the resultant moire pattern becomes closely sinusoidal in intensity distribution. And, when the LC grating pattern is moved, the projected pattern can be shifted arbitrarily in phase. Surface profiles of some samples are measured to show validity of hybrid grating projection and utility of the prototype system.
In the conventional measurement of strain, resistance wire types of strain gauges have been used in most of cases. However, other kinds of strain gauges have been reported recently and optical fiber gauges appeared on the market. Here, instead of a conventional strain gauge made of a metal wire, we propose an optical fiber gauge. This gauge consists of two fibers for transmitting a beam from a light source and for receiving a reflecting-back beam, and in between them a concave mirror with a hole is settled. This mirror is used for transmission and partial reflection of the beam. When strain is given to the testing specimen to which the gauge is adhered, small displacement between two fiber ends is brought. The construction of this gauge is so sensitive to gap change between the fibers that high sensitivity is realized in measurement. In addition to high sensitivity, this gauge is featured by a small size and short gauge length. To verify this principle, experiments are repeated by using a thin plate specimen made of copper. The gauge is made of a plastic fiber of 0.5 mm in diameter and a small concave miro with a pinhole. Due to this mirror construction, the fluctuation of the beam intensity can be checked and the stable normalized output signal is obtained. Because the normalized signal is obtained form two signals; transmitted and reflected signals. An experimental result showed a high sensitivity in experimental measurement, and even for the intentional fluctuation of the beam intensity, we could get same measuring result in strain measurement.
This paper describes a grating projection method for the measurement of surface profiles of objects. In this kind of profilometry, a grating with binary transmittance distribution has been utilized usually. And in these cases such a problem is known as an error is caused due to the non-sinusoidal transmittance distribution of the grating. And another difficulty is also indicated that shifting of the grating is given by mechanical movement of the grating. Here we propose to use a hybrid grating is given by mechanical movement of the grating. Here we propose to us a hybrid grating which consists of a conventional binary grating and a liquid crystal binary grating. Then moire pattern is produced by superposing these two binary gratings. When two binary gratings are overlapped with an appropriate gap, the resultant more pattern becomes closely sinusoidal in intensity distribution. The, in the optical arrangement for profile measurement using this hybrid grating, when the LC gratin pattern is moved, the projected pattern is shifted arbitrarily in phase. Surface profiles of some samples are measured to show validity of the more pattern projection and utility of the prototype system.
Optically driven small machines have such features as easily miniaturized in fabrication and as controlled by optical energy supplied in wireless. We report an optically controlled machine which moves like a catepillar on the basis of photo-thermal effect. This miniaturized machine fundamentally consists of two parts: a body made of shape memory alloys and springs and feet made of magnets and temperature-sensitive ferrites. Th effect can stick to the carbon steel floor due to magnetic force balance caused by projected beam, and the body repeats stretching and shrinking using deformation of shape memory alloys caused by switching on and off of projected beam. A prototype is fabricated in trial with a size of 35 mm by 12 mm. As an experimental result, it proved that they could move at the speed of 8.7 mm per cycle on a ceiling as well as on a horizontal floor and it could climb a slope as steep as 50 degree. To improve the ability of this prototype, we newly developed a smaller machine with the total length of 20 mm by 15 mm and the weight of 1.1 g. Because of lighter weight of this machine, it could climb any slope including a vertical wall.
This paper describes a device for measuring the three dimensional surface profile using a grating projection method. A phase shifting technique without any mechanical moving is expected for profile analysis. A grating that is a key component in this technique is made using an active controlled liquid crystal (LC). This LC grating has the performances of more than 8 bits of gray levels and its grating period is 50 micro-meters per line without any colored filters. Surface profiles of some samples are measured for the demonstration of the system.
A grating projection method using a stereomicroscope is developed to provide a surface profile measurement. The phase shifting technique is applied for high accuracy detection of the projected fringe. To overcome 2(pi) phase jump caused by large step in height and to detect absolute height from the fringe number, contrast detection of the projected pattern is available. The contrast varies in relation with the distance between the sample and the objective lens. This variation is almost as same as optical sectioning that is usually used in confocal microscopy. The fast reconstruction procedure is proposed to analyze the focal point from a few images. This method is demonstrated and conformed to measure the steep surface profile of a test sample.
Silicon wafers are widely used for semiconductors. Its flatness is very important in the inspection process. An oblique incidence interferometer with a one step phase- shifting technique using only one image was proposed for its inspection. This technique is developed for precise surface profile measurement even if the sample is mirror surface with multiple reflection between measurement and reference surface. To cover a large measurement area, the extension of the measurement area is archived to combine small area one after the another.