THREE-DIMENSIONAL OBJECT INFORMATION MEASURING DEVICE
|Posted date||Jun 28, 2018|
|International application number||2018JP005604|
|International publication number||WO 2018147473|
|Date of international filing||Feb 9, 2018|
|Date of international publication||Aug 16, 2018|
|Title||THREE-DIMENSIONAL OBJECT INFORMATION MEASURING DEVICE|
|Abstract||A three-dimensional object information measuring device (1) is provided with: a linearly polarized light converting unit (22) which converts object light arriving from an object into linearly polarized light; a shearing interferometer (2) which causes the object light to undergo shearing interference; a circularly polarized light converting unit (28) which converts vertically polarized light and horizontally polarized light in interference light obtained by means of the shearing interferometer into circularly polarized light; an interference fringe acquiring unit (3) which records the circularly polarized light by means of a single image capture; and a calculating unit (4) which computes complex amplitude information of the object from the image recorded by the interference fringe acquiring unit (3). In the recorded image, the phase differs depending on the pixel. The calculating unit (4) is provided with: an extracting unit (41) which extracts the pixels from the recorded image by phase, and generates a plurality of sets of extracted data comprising pixels having the same phase and pixels having a missing pixel value; an interpolating unit (42) which generates a plurality of sets of interpolated data approximating a plurality of interference images having mutually different phases, by subjecting each of the plurality of sets of extracted data to pixel interpolation; and a computing unit (43) which computes the complex amplitude information from the plurality of sets of interpolated data.|
|Outline of related art and contending technology||
The industry in recent years, industry, with the development of medicine, a higher degree of accuracy, high-speed measurement technology is demanded.In particular, the complex amplitude information and phase information of the object is important as two-dimensional information 3, the structure of the deformation or the like phenomenon is very beneficial to know.
For example, an object that emits fluorescent light or heat or natural illumination light from the light source such as the complex amplitude of the measurement object, measuring the precise shape of the product, the dynamic observation of a living body, the internal structure of a living body such as important in imaging applications, in addition, the thickness distribution of an object, an object such as a refractive index of the structure 3 may also be a three-dimensional shape information is important, non-invasive, non-contact, high-sensitivity, parallel processing and the like has characteristics that are essential for the optical measurement technology.
Furthermore, as two-dimensional information and phase information 3 is also important, the wavefront of the light emitted from the laser beam to accurately grasp, in addition, the structure of a transparent object for grasping the information of the wavefront of the light transmitted through the measurement is being sought.For example, jets of gas measurement and not visible in the detailed examination of the lens, the thickness of a transparent object such as a droplet or cells, such as measuring the refractive index distribution, the wavefront information (phase information) are applied to a wide variety.In addition, if the reflection object the shape of the surface of the object and the phase information can be measured precisely.
(The measurement of the complex amplitude of the background) the motion of the object or a small amount of change in the shape of the observed phenomenon occurs at a high speed of a most simple way, a high-speed camera brightness of the object information (intensity information) only a method of direct imaging.However, in order to accurately measure the object information, not only the brightness information (intensity information), the complex amplitude information (i.e., brightness information (intensity information) and phase information) is required.For example, high speed is captured by the camera, only the intensity information of the object can be recorded, in addition, the transparent object cannot be applied to the problem.
As a method for solving the above problems, the complex amplitude information obtained by the interference measurement method disclosed in the optical measurement technology.As an example, the holographic apparatus using the optical system shown in Fig. 19. 50 Holography apparatus shown in Fig. 19, the laser source with higher coherence light emitted from the laser light 51, in order to irradiate the measurement target 100 in the beam splitter 52 light (object light) and the reference light separated.The objective lens 53a emits light which is the object, lens 54a, mirror 55a is irradiated through the measurement target 100.The measurement target 100 the reflected light from the beam splitter 56 via the object light is incident to the CCD camera 57.On the other hand, the reference light, the measurement target path 100 does not exist, specifically, the mirror 55b, objective lens 53b, lens 54b, mirror 55c and CCD camera 57 via the beam splitter 56 is incident.Thus, in the CCD camera 57, the interference fringes of object light and reference light are captured, based on the interference fringes calculated by the computer performing a predetermined measurement target 100 of the complex amplitude information (intensity information and phase information) is obtained.
These holographic device, to an image pickup device of the CCD camera 57, the reference light is irradiated at right angles to the interference fringes are produced.Therefore, the interference fringes in the reproduced image is obtained by converting Fresnel, not only the image +1 necessary for the first-order diffraction order diffracted image and unnecessary order diffracted image 0-1 overlap, it is difficult to obtain a clear image becomes.Therefore,-1 or 0 order diffraction image without the first-order diffraction image in order to obtain a clear image, to shift the phase of the reference light phase shift digital holography apparatus to a plurality of stages has been proposed (Patent Document 1).For example, by the piezoelectric element, step or phase of the reference light 3 is shifted to the step 4 the phase shift digital holography apparatus has been proposed.In addition, as a method to shift the phase of the reference light, the phase shift digital holography apparatus using the phase plate has been proposed.
Such a phase shift digital holography apparatus, the phase of the reference light, for example π / 2rad changed by each one, a plurality of interference fringes recorded in the CCD camera 57.The plurality of the interference pattern by numerical calculation, and the-1-order diffraction image 0 without the first-order diffraction image can be obtained the reproduced image.However, the need for a plurality of interference fringes, the movement of the object is fast in case of fast changes in the shape of the minute, that is to occur at high speed cannot be recorded or reproduced is a problem.
On the other hand, Patent Document 2 is, in order to solve the above problem, a plurality of different phase values with each other and the reference light, emitted from the subject irradiated with light of an object obtained by interference between the phase based on the distribution data, to generate a reproduced image of the object reproduction image generating unit by using a digital holography apparatus is proposed.That is, a phase value of the incident light from a plurality of different reference light emitted from the reference light is converted into a group and the phase-shift element, the object light and reference light group and the interference generated by the phase distribution data is recorded in the image pickup surface having an image capturing unit, reproduction image generating unit, the phase distribution based on the information data to generate a reproduced image of the subject.
The digital holography apparatus according to the present invention, the light incident on the phase value from a plurality of different reference light can be obtained at the same time.A plurality of reference light and object light from the reference group by causing interference between the phase distribution data is obtained, each phase value of the reference light interfere with each other and object data and the mixed state.Therefore, the phase of the distribution data information is used, 1 different phases to take a value of the reference light interfere with the object light and a plurality of data can be obtained, in order to obtain a clear image can be obtained instantaneously necessary information.Therefore, and a moving subject, such as deformation of the instantaneous image of the subject, the subject of the real-time observation or the like can be realized.
However, in the digital holography apparatus, the laser light source such as a light source having high coherence is required, so that noise is generated due to the laser light source, the reference light since the interference of the object light, the optical element is used because of a large apparatus size, complicated, the optical element is installed in high installation accuracy is required for a longer time for installation is difficult and there is a problem.
Of the coherent light source such as laser light is not used, the natural light, fluorescent, such as heat from the light source of coherent light having a low interference is used as a measurement, Non-Patent Document 1 and Non-Patent Document 2 is of the self-interference.Fig. 20 is, for the measurement device to the non-patent document 1 is a schematic diagram of a 60.In the measuring device 60, the spatial light modulator (SLM) 61 through the same optical path by using the generated light waves of the type 2, they interfere with each other are generated as a result of the method for recording stripes, the display SLM61 to change the pattern it is necessary to record sequentially.Therefore, the measuring device 60 can be simplified, a diffraction optical element SLM61 such as diffraction efficiency drops due to the use of the reproduced image is degraded, due to the diffraction image is formed in order to form the multiple multi-image of the image distortion aberration occurs is generated and the like, in addition, since the sequential recording method, and a moving subject, such as instantaneous deformation of the subject, and the like of the subject in real-time observation of a problem that cannot be realized.
In non-patent document 3, 1 in order to play back the recording of the image, 2 is divided into two light waves, one of the wavefront of the light has been proposed a method of tilting.In non-patent document 3, one of the narrow-band bandpass filter is used for tilting the optical coherence required to increase.Further, when 2 is divided into two light waves to one wave of a different optical path 2 to pass, easily affected by external disturbance such as vibrations of the problem.
In non-patent document 4, 1 in order to play back the recording of the image having the polarization characteristics is used as a lens has been proposed.However, in this method, theoretically, a special lens having optical polarization characteristics is required, this element is difficult to achieve in practice, achieved by the the problem is extremely expensive.
In non-patent document 5, two different polarized light wave 2 is generated, using a Pockels cell phase shift in the image is also reported a technique for playing is, because of the use of special elements is poor in versatility, since it is necessary to sequentially recorded in the measurement of the dynamic object is not a problem.
Phase (phase information of the background measurement) for measuring the reference light to the conventional interference measuring technique is used, the external disturbance such as vibration and temperature very weak, the practical application is not affected by the disturbance must be so.Therefore, the reference light is not used, the same optical path through the self-interference using the interference method to suppress the influence of the disturbance is a new interference measurement techniques have been reported.However, a plurality of interference fringe image must be recorded and the sequential, each image is acquired because of the need for a time interval, eventually under the influence of external vibration has been a problem.
As a technique to solve the above problem, in recent years, the instantaneous phase image can be acquired several techniques have been reported.For example, as a method of measuring the wavefront of the light, and the wave reflected from the surface of the subject, the reflected wavefront that is superimposed on the wave front slightly displacing the shearing interferometer is used.Another wavefront measuring the shearing interferometer without the need for the reference light, and for recording the interference of its own, is not easily affected by disturbance of the feature.In addition, the shearing interferometer using polarized light among the plurality of interference images can be measured in the radial shearing interferometer 1 shot has been proposed (Non-Patent Document 6).However, Non-Patent Document 6 is of the radial shearing interferometer, the interferometer required very large number of optical elements, optical adjustment is complicated and difficult, in addition, the optical system becomes large and the small and low-cost of the apparatus has a problem in practical use is difficult.
In addition, the diffraction element can be used in more simple interferometer wavefront measurement techniques have been reported (Non-Patent Document 7).This device is complex and does not require an interferometer for use in place of the diffraction element, is significantly affected by the diffraction element, the polarization direction different from diffraction efficiency deterioration of the reproduced image.In addition, one 2 for the twisted path, the problem is easily affected by disturbance.
In addition, the diffraction element is not required, a relatively simple Sagnac interferometer is an interferometer 2 may be a combination of two wavefront measurement technology has been proposed (Non-Patent Document 8).However, the need for sequential recording will be greatly affected by vibration, the wavefront cannot be instantaneously measured in a problem.
On the other hand, Patent Document 2 according to the configuration of the digital holography apparatus, taking 1 different phase value and the reference light interfere with the object light and a plurality of images can be obtained, the reproduced image is of course, is also instantaneously phase image can be reproduced.Then, and a moving subject, such as deformation of the instantaneous image of the subject, the subject of the real-time observation or the like can be realized.
However, in the digital holography apparatus, since the interference light and the reference, the optical element is used because of a large apparatus size, complicated, requires high positional accuracy of the optical element is provided for longer time for installation is difficult, vulnerable to external disturbance which is problematic.
|Scope of claims||
|IPC(International Patent Classification)||
Contact Information for " THREE-DIMENSIONAL OBJECT INFORMATION MEASURING DEVICE "
- National University Corporation Kyoto Institute of Technology Intellectual Property,Research Promotion
- URL: http://www.ipo.kit.ac.jp/
- Address: 1,Matsugasaki Hashikami-cho, Sakyo-ku, Kyoto-shi, Kyoto, Japan , 606-8585
- Fax: 81-75-724-7030