Multi-directional projection type moire interferometer and inspection method of using the same

A multi-directional projection type moiré interferometer includes a stage, an image formation part, rotating mirrors, fixed mirrors, and a pattern illumination generating part. The stage moves a target object. The image formation part is provided above the stage to take a pattern image reflected from the target object placed on the stage. The rotating mirrors are vertically arranged and inclined at an angle different from each other to receive a pattern illumination, change the optical path of the pattern illumination, and emit the pattern illumination. The fixed mirrors emit the pattern illumination, emitted from the rotating mirrors, toward the target object. The pattern illumination generating part emits the pattern illumination toward the rotating mirrors. The pattern illumination generating part includes a grating board, and grating elements are formed at the grating board to emit the pattern illumination toward the rotating mirrors.

BACKGROUND

The present invention relates to a multi-directional projection type moire interferometer and an inspection method of using the same, and more particularly, to a multi-directional projection type moire interferometer capable of multi-directionally emitting the pattern illumination toward a target object to eliminate a complex shadow area of the target object according to various shapes thereof, and an inspection method of using the same.

Hereinafter, a conventional projection type moire interferometer will be described with reference toFIG. 1. As shown inFIG. 1, the conventional moire interferometer includes a plurality of projectors3generating a bi-directional pattern illumination and one image formation part4.

The plurality of projectors3is provided to be inclined on one side and another side of the image formation part3, respectively. The projector3includes an illumination part3a, a grating element3e, a grating actuator3f, and an emitting lens3gto generate the pattern illumination. The illumination part3aincludes an illumination source3band a plurality of emitting lenses3cand3d. After the illumination that is generated from the illumination source3bof the illumination part3apasses through the plurality of emitting lenses3cand3d, the pattern illumination is formed via grating patterns formed on the grating element3e. The pattern illumination according to the grating patterns passes through the emitting lens3gand is bi-directionally emitted toward a target object1placed on an XY table2. The XY table2is actuated by a table actuator2ato move the target object into either X or Y direction.

The image formation part4includes a charge-coupled device (CCD) camera4a, an imaging lens4b, and a filter4c. The image formation part4takes a pattern image according to the pattern illumination reflected from the target object1. Also, a circular lamp5is provided below the image formation part4. The circular lamp5is used as an illumination source when taking a particular shape of the target object1. When an N-bucket algorithm is applied to inspect a 3 dimensional (3D) shape of the target object1in a state where the target object1is placed on the XY table2, the image formation part4takes N images while moving the grating element3evia the grating actuator3fN times. When the N images are taken and obtained, a control unit (not shown) obtains phase information using the obtained images. Also, when the plurality of projectors3obtains each phase information, the control unit calculates an integrated phase map in which noise is removed, and inspects a height-map and a 3D shape of the target object1using the calculated integrated phase map.

The conventional projection type moire interferometer emits an illumination toward a target object and inspects the target object in a state where a plurality of projectors is provided to face each other based on the target object. In this case, if the target object has a very complex shape, a shadow region may be incompletely removed, which results in inaccurately inspecting the target object.

SUMMARY OF THE INVENTION

To solve the above-described problem in the conventional art, the present invention provides a multi-directional projection type moire interferometer capable of multi-directionally emitting a pattern illumination toward a target object to remove a complex shadow region according to various shapes of the target object, and an inspection method of using the same.

The present invention also provides a multi-directional projection type moire interferometer which can reduce a manufacturing cost since a multi-directional projection type moire interferometer can be constructed in compact by readily changing a projection direction of a pattern illumination via a rotating mirror part to emit an illumination pattern toward a target object, and controlling a movement of a grating board by installing a plurality of grating elements on the grating board.

According to an aspect of the present invention, there is provided a multi-directional projection type moire interferometer including: an XY stage being provided to be movable by a plurality of stage actuators to move a target object into X and Y directions; an image formation part being provided above the XY stage to take a pattern image that is reflected from the target object placed on the XY stage; a first rotating mirror part being provided on one side of the image formation part to receive a pattern illumination, change the optical path of the pattern illumination, and emit the pattern illumination; a second rotating mirror part being provided on another side of the image formation part to receive a pattern illumination, change the optical path of the pattern illumination, and emit the pattern illumination; a plurality of first fixed mirror parts being provided on one side of the first rotating mirror part to emit the pattern illumination, emitted from the first rotating mirror part, toward the target object; a plurality of second fixed mirror parts being provided on another side of the second rotating mirror part to emit the pattern illumination, emitted from the second rotating mirror part, toward the target object; and a first pattern illumination generating part being provided to be capable of emitting the pattern illumination toward the first and the second rotating mirror parts, and generate the pattern illumination.

According to another aspect of the present invention, there is provided an inspection method using a multi-directional projection type moire, the method including: moving a target object to a setup location after adjusting a rotating angle of rotating mirrors of first and second rotating mirror parts, switching on a fifth illumination source, and implementing a secondary inspection of the target object via an image formation part; switching on any one of first through fourth illumination sources when the target object is moved to the setup location; verifying by a central control unit whether the selected illumination source is switched on; moving a grating element corresponding to the selected illumination source by 1/N pitch by moving a grating board when the selected illumination source is switched on; taking, by the image formation part, a pattern image reflected from the target object when the grating element is moved; verifying, by the central control unit, whether the grating element is an Nth pitch movement while acquiring the pattern image; obtaining a phase map using the pattern image taken in each movement when the grating element is moved by the Nth pitch; verifying, by the central control unit, whether first through fourth phase maps are obtained when the phase map is obtained; and inspecting a 3D shape by calculating, by the central control unit, an integrated phase map using the obtained first through the fourth phase maps when the first through the fourth phase maps are obtained, and then calculating an integrated height map using the integrated phase map, wherein nose is removed from the integrated phase map.

DETAILED DESCRIPTION

First Embodiment

Hereinafter, a first embodiment of a multi-directional projection type moire interferometer according to the present invention will be described with reference to the accompanying drawings.

FIG. 2is a perspective view illustrating a configuration of a multi-directional projection type moire interferometer according to a first embodiment of the present invention. As shown inFIG. 2, the multi-directional projection type moire interferometer includes an XY stage10, an image formation part110, a first rotating mirror part120, a second rotating mirror part130, a plurality of first fixed mirror parts140and150, a plurality of second fixed mirror parts160and170, and a first pattern illumination generating part180. Hereinafter, a process of multi-directionally emitting a pattern illumination toward a target object1and thereby inspecting the target object1will be sequentially described.

The XY stage10is provided to be movable by a plurality of stage actuators11and12so as to move a target object1into X and Y directions.

The image formation part110is provided above the XY stage10so as to take a pattern image that is reflected from the target object1placed on the XY stage10. The image formation part110includes a camera111, an imaging lens112, and a first filter113. Hereinafter, a configuration of each component of the image formation part110will be described.

The camera111adopts any one of a charge-coupled device (CCD) camera and a complementary metal oxide semiconductor (CMOS) camera to take a pattern image. The imaging lens112is provided below the camera111to image the pattern image reflected from the target object1. The first filter113is provided below the imaging lens112to pass the pattern image reflected from the target object1. In this instance, the first filter113adopts any one of a frequency filter, a color filter, and an optical strength adjustment filter. The image formation part110further includes a fifth illumination source114in its lower portion to generate illumination for a secondary inspection of the target object1. The fifth illumination source114includes any one of a plurality of luminescent diodes and a domed multi-layered circular lamp.

The first rotating mirror part120is provided on one side of the image formation part110to receive the pattern illumination, change the optical path of the pattern illumination, and emit the pattern illumination. Specifically, the first rotating mirror part120changes an incidence angle of the pattern illumination that is emitted toward the target object1and thereby emits the pattern illumination. The first and the second rotating mirror parts120and130change the optical path of the pattern illumination and thereby emit the pattern illumination. As shown inFIG. 4, the first and the second rotating mirror parts120and130include a plurality of rotating mirror elements120aand130athat are arranged in a multi-layer, so that ends of the rotating mirror parts120aand130amay vertically face each other, and multi-directionally emit the pattern illumination toward the target object1.

The plurality of rotating mirror elements120aand130aincludes mirror rotating instruments121and131, holders122and132, and rotating mirrors123and133, respectively. Hereinafter, the configuration of each component will be described. The mirror rotating instruments121and131may adopt a motor. As shown inFIG. 4, the mirror rotating instruments121and131are mounted to one side and another side of the image formation part110, and the holders122and132are rotatably provided above the mirror rotating instruments121and131, respectively. The rotating mirrors123and133are provided on the holders122and132to be rotatable on the holders122and132with being supported by the mirror rotating instruments121and131, respectively.

The plurality of first fixed mirror parts140and150is provided on one side of the first rotating mirror part120to emit the pattern illumination, emitted from the first rotating mirror part120, toward the target object1. The plurality of second fixed mirror parts160and170is provided on another side of the second rotating mirror part130to emit the pattern illumination, emitted from the second rotating mirror part130, toward the target object1.

The plurality of the first and the second fixed mirror parts140,150,160, and170, emitting the pattern illumination toward the target object1, includes second filters141,151,161, and171, and fixed mirrors142,152,162, and172, respectively. The second filters141,151,161, and171receive the pattern illumination emitted from the first and the second rotating mirror parts120and130, and filter and emit the pattern illumination. The fixed mirrors142,152,162, and172are inclined with respect to the second filters141,151,161, and171, respectively, to receive the pattern illumination emitted from the first and the second rotating mirror part, and emit the pattern illumination toward the second filters141,151,161, and171. When the pattern illumination is emitted toward the target object1, the second filters141,151,161, and171adopt any one of a frequency filter, a color filter, a polarized filter, and an optical strength adjustment filter to filter and emit the pattern illumination.

The first pattern illumination generating part180is provided to be capable of emitting the pattern illumination toward the first and the second rotating mirror parts120and130. Specifically, the first pattern illumination generating part180is provided in front of each of the first and the second mirror rotating parts120and130so as to emit the pattern illumination toward the rotating mirrors123and133of the first and the second rotating mirror parts120and130respectively. As shown inFIG. 3, the first pattern illumination generating part180, generating the pattern illumination, includes first through fourth illumination sources181a,181b,181c, and181d, first through fourth grating elements182a,182b,182c, and182d, a grating board183, a grating board actuator184, and a first through fourth emitting lenses185a,185b,185c, and185d. Hereinafter, the configuration of each component will be described.

The first through the fourth illumination sources181a,181b,181c, and181dgenerate the illumination, and are installed on one side surface of the grating board183. The grating board183includes the first through the fourth grating elements182a,182b,182c, and182dwhich generate the pattern illumination and emit the generated pattern illumination when the illumination is generated from the first through the fourth illumination sources181a,181b,181c, and181d. The first through the fourth grating elements182a,182b,182c, and182dare applied either gratings or liquid crystal devices (not shown), respectively.

The grating board actuator184is provided on one side surface of the grating board183to vertically move the grating board183and thereby vertically move the first through the fourth grating elements182a,182b,182c, and182d. The grating board actuator184includes a linear motion (LM) guide184a, an LM rail184b, and an LM actuator184c. The LM guide184ais provided on the grating board183, and the LM rail184bguides the LM guide184a. Also, the LM actuator184cdrives the LM guide184ato move along the LM rail184band move the grating board183. The LM actuator184cmoving the grating board183adopts any one of a ball screw, a linear motor, and a PZT actuator. When the PZT actuator is adopted as the LM actuator184c, the present invention may directly install the grating board183in the PZT actuator.

The first through the fourth emitting lenses185a,185b,185c, and185dare provided on one side surface of the grating board183to correspond to the first through the fourth grating elements182a,182b,182c, and182dso as to emit the pattern illumination that is emitted from the first through the fourth grating elements182a,182b,182c, and182d.

The above configuration may further include a circuitry to control the multi-directional projection type moire interferometer according to the present invention. As shown inFIG. 5, the circuitry of the multi-directional projection type moire interferometer includes an image acquisition unit210, a module control unit220, and a central control unit230.FIG. 5is a diagram illustrating a configuration of a multi-directional projection type moire interferometer of the present invention, and schematically shows the multi-directional projection type moire interferometer shown inFIG. 2. Specifically,FIG. 5schematically shows the multi-directional projection type moire interferometer ofFIG. 2to represent that it is possible to multi-directionally emit the pattern illumination toward the target object1based on the image formation part110using the first rotating mirror part120, the second rotating mirror part130, the plurality of first fixed mirror parts140and150, the plurality of second fixed mirror parts160and170, and the first pattern illumination generating part180.

As shown inFIG. 5, the image acquisition part210receives the pattern image taken by the image formation part110and transmits the received pattern image. The module control unit220controls the XY stage10, the first and the second rotating mirror parts120and130, and the first pattern illumination generating part180, so that the first pattern illumination generating part180may generate the pattern illumination, the first and the second rotating mirror parts120and130rotate and emit the pattern illumination toward the plurality of the first and the second fixed mirror parts140,150,160, and170, and thereby the pattern illumination is emitted toward the target object being moved by the XY stage10.

The module control unit220controlling the pattern illumination to be emitted toward the target object1includes a table controller221, an illumination controller222, a grating controller223, and a rotating mirror controller224. Hereinafter, the configuration of each component will be described.

The table controller221drives a plurality of stage actuators11and12to move the XY stage10toward X and Y directions according to control of the central control unit230. The illumination controller222drives the first pattern illumination generating part180to generate the pattern illumination, or driving the fifth illumination source114to generate the illumination for the secondary inspection according to control of the central control unit230. The fifth illumination source114is included in the image formation part110. The grating controller223drives the grating board actuator184to move the grating board183according to control of the central control unit230. In this instance, the grating board actuator184is included in the first pattern illumination generating part180and the first through the fourth grating elements182a,182b,182c, and182dare formed on the grating bard183. Also, the rotating mirror controller224drives the first and the second rotating mirror parts120and130to receive the pattern illumination emitted from the first pattern illumination generating part180, change the optical path of the pattern illumination, and emit the pattern illumination according to control of the central control unit230.

When the optical path of the pattern illumination is changed by driving of the module control unit220and the pattern image, which is emitted toward and reflected from the target object1, is taken by the image formation part110, and then the taken pattern image is output via the image acquisition part210, the central control unit230receives the output pattern image. The central control unit230controls the module control unit220to emit the pattern illumination toward the target object1that is being moved by the XY stage10. When the reflected pattern image is taken via the image formation part10and is transmitted via the image acquisition part210, the central control unit230acquires a phase map from the pattern image, calculates the height of the target object using the phase map, and inspects a 3D shape of the target object1.

Second Embodiment

A multi-directional projection type moire interferometer according to the second embodiment will be described with reference to the accompanying drawings.

As shown inFIGS. 6A and 6B, the multi-directional projection type moire interferometer according to the second embodiment includes an XY stage10, an image formation part110, a first direct reflective mirror240, a second direct reflective mirror250, a second pattern illumination generating part260, a first pattern illumination case270, a first pattern illumination elevator280, and a pattern illumination rotating part290. Hereinafter, the configuration of each component will be described.

The configuration of the above-described XY stage10and the image formation part110is the same as the XY stage10and the image formation part110that are applied to the multi-directional projection type moire interferometer according to the first embodiment. The image formation part case110ais provided outside of the image formation part110.

The first direct reflective mirror240is inclined on one side of the image formation part110to emit the pattern illumination toward one side of the target object1placed on the XY stage10and thereby reflect a pattern image toward the image formation part110. The second direct reflective mirror250is inclined on the other side of the image formation part110to be below the first direct reflective mirror240, to emit the pattern illumination toward another side of the target object1paced on the XY stage10and thereby reflect the pattern image toward the image formation part110. The second pattern illumination generating part260is provided one side of the first and the second direct reflective mirrors240and250to generate the pattern illumination and emit the generated pattern illumination toward the first and the second direct reflective mirrors240and250. The first pattern illumination case270is formed in a straight type. The first and the second direct reflective mirrors240and250, and the second pattern illumination generating part260are contained in the first pattern illumination case270.

The first pattern illumination elevator280is mounted to the image formation part case110aof the image formation part110, and includes a motion guide281, a motion member282, and a motion instrument183to vertically move the first pattern illumination case270. The motion guide281is provided in the image formation part case110aand the motion member282is provided on the motion guide281to vertically move along the motion guide281. Also, the motion instrument283is provided on the first pattern illumination case270and provides a driving force to vertically move the first pattern illumination case270. The motion instrument283is controlled by a pattern illumination elevator control part (not shown) which controls the first pattern illumination elevator280, to vertically move the first pattern illumination case270and thereby adjust a focal distance according to the target object1.

The pattern illumination rotating part290includes the first pattern illumination case270on its one side, and includes the first pattern illumination elevator280on its another side. Also, the pattern illumination rotating part290includes a rotating member291, a rotary force transfer member292, and a motor293to rotate the first pattern illumination case270into a direction indicated by an arrow ofFIG. 6Band thereby multi-directionally emit the pattern illumination, emitted from the second pattern illumination generating part260, toward the target object1. The rotating member291includes an empty member inside, such as bushing. The inside of the rotating member291is mounted to the first pattern illumination elevator280and outside thereof is mounted to the first pattern illumination case270. The rotary force transfer member292includes a gear or a belt to transfer to the rotary member291the rotary force that is generated from the motor293. The motor293is controlled by a pattern illumination rotation control unit (not shown) to rotate the first pattern illumination case270and thereby multi-directionally inspect the target object1.

Third Embodiment

A multi-directional projection type moire interferometer according to a third embodiment will be described with reference to the accompanying drawings.

As shown inFIGS. 7A and 7B, the multi-directional projection type moire interferometer according to the third embodiment includes an XY stage10, an image formation part110, a first direct reflective mirror240, a second direct reflective mirror250, a second pattern illumination generating part260, a third direct reflective mirror300, a fourth direct reflective mirror310, a third pattern illumination generating part320, a second pattern illumination case330, and a second pattern illumination elevator340. Hereinafter, a configuration of each component will be described with reference toFIGS. 7A and 7B.

In the multi-directional projection type moire interferometer according to the third embodiment, the configuration of the XY stage10, the image formation part110, the first direct reflective mirror240, the second direct reflective mirror250, and the second pattern illumination generating part260are the same as the multi-direction projection type moire interferometer according to the second embodiment, and thus further detailed descriptions will be omitted. In this instance, in addition to the first direct reflective mirror240which emits the pattern illumination toward one side of the target object1in one direction and the second direct reflective mirror250which emits the pattern illumination toward another side of the target object in one direction, the multi-directional projection type moire interferometer according to the third embodiment further includes the third direct reflective mirror300, the fourth direct reflective mirror310, the third pattern illumination generating part320, the second pattern illumination case330, and the second pattern illumination elevator340so as to multi-directionally inspect the target object1without rotating the second pattern illumination generating part260.

The third direct reflective mirror300is provided at the same height as the first direct reflective mirror240to be orthogonal to the first direct reflective mirror, to emit the pattern illumination toward one side of the target object1placed on the XY stage10in another direction and thereby reflect the pattern image toward the image formation part110. The fourth direct reflective mirror310is provided at the same height as the second direct reflective mirror250to be orthogonal to the second direct reflective mirror250, to emit the pattern illumination toward another side of the target object1placed on the XY stage10in another direction and thereby reflect the pattern image toward the image formation part110. As described above, the third and the fourth direct reflective mirrors300and310emit the pattern illumination toward one side and another side of the target object1placed on the XY stage10, in another direction. Also, the first and the second direct reflective mirrors240and250emit the pattern illumination toward one side and another side of the target object1, placed on the XY stage, in one direction. Therefore, it is possible to multi-directionally emit the pattern illumination via the first through the fourth direct reflective mirrors240,250,300, and310. In this instance, the other direction designates a direction that is different from the one direction based on the target object1, for example, a direction that is orthogonal to the one direction. The third pattern illumination generating part320is provided on one side of the third and the fourth direct reflective mirrors300and310so as to generate the pattern illumination toward the third and the fourth direct reflective mirrors300and310. The second pattern illumination case330is formed in a cross type, and includes the first through the fourth direct reflective mirrors240,250,300, and310, and the second and the third pattern illumination generating parts260and320.

The second pattern illumination elevator340includes a motion guide which is provided on the image formation part case110aof the image formation part110and vertically moves the second pattern illumination case330, a motion member342, and a motion instrument343. The configuration and operation of each component is the same as the motion guide281, the motion member282, and the motion instrument283of the first pattern illumination elevator280, and thus will be omitted. In this instance, the second pattern illumination case330is provided on one side surface of the motion member342and the motion guide341is provided on another side surface of the motion member342. Therefore, the motion member342is vertically moved along the motion guide341.

The first through the fourth direct reflective mirrors240,250,300, and310, which are applied to the multi-directional projection type moire interferometer according to the second and the third embodiments, may be fixed like the first and the second direct reflective mirrors240and250ofFIG. 6A. Also, like the first and the second direct reflective mirrors ofFIG. 7A, the first through the fourth direct reflective mirrors240,250,300, and310may be rotated to change the optical path of the pattern illumination, that is, to adjust the incidence angle of the pattern illumination that is emitted toward the target object1.

To adjust the incidence angle of the pattern illumination, the first through the fourth direct reflective mirrors240,250,300, and310may further include a mirror rotating instrument410and a holder420like the first direct reflective mirror240ofFIG. 7A. The first direct reflective mirror240indicated by a dotted line ofFIG. 7Ais when the first direct reflective mirror240installed in the second pattern illumination case330ofFIG. 7Ais viewed from a direction K, and is given to more concisely describe the configuration of the mirror rotating instrument410and the holder420. The mirror rotating instrument410included in the first through the fourth direct reflective mirrors240,250,300, and310generates the rotary force to rotate the first through the fourth direct reflective mirrors240,250,300, and310. The holder420is mounted to the mirror rotating instrument410to support the first through the fourth direct reflective mirrors240,250,300, and310.

As shown inFIG. 8, the second and the third pattern illumination generating parts260and320, which are applied to the multi-directional projection type moire interferometer according to the second and the third embodiments, may include first and second illumination sources181aand181b, first and second grating elements182aand182b, a grating board183a, a grating board actuator184, and first and second emitting lenses185aand185bso as to generate the pattern illumination and emit the generated pattern illumination. The configuration and operation of each component is the same as the first pattern illumination part180ofFIG. 3which is applied to the multi-directional projection type moire interferometer according to the first embodiment, and thus further descriptions will be omitted here. The pattern illumination emitted from the first and the second emitting lenses185aand185bis emitted toward the first and the second direct reflective mirrors240and250, respectively, or is emitted to the third and the fourth direct reflective mirrors300and310, respectively. Also, the grating board183aincludes two, i.e. the first and the second grating elements182aand182b, whereas the grating board183ofFIG. 3, which is applied to the multi-directional projection type moire interferometer according to the first embodiment, includes the first through the fourth grating elements182a,182b,182c, and182dofFIG. 3, which is different.

As shown inFIG. 7A, a cooler350that is applied to the multi-directional projection type moire interferometer according to the second and the third embodiments may be further provided on one side of the second and the third pattern illumination generating parts260and320so as to remove the heat generated from the first and the second illumination sources181aand181bof the second and the third pattern illumination generating parts260and320. The cooler350adopts any one of a cooling fan, a thermoelectric element, and a hit sink member to remove the heat generated from the second and the third pattern illumination generating parts260and320.

An inspection method using the multi-directional projection type moire interferometer constructed as above will be described with reference toFIGS. 2,5, and9.

In operation S110, the inspection method moves the target object1to a setup location via the XY stage10after adjusting a rotating angle of the rotating mirrors123and133of the first and second rotating mirror parts120and130, switching on the fifth illumination source114, and implementing a secondary inspection of the target object1via the image formation part110.

Operation S110of moving the target object1to the setup location includes operation S111of rotating and thereby initially setting the rotating mirrors123and133of the first and the second rotating mirror parts120and130so as to multi-directionally emit the pattern illumination toward the target object1, operation S112of switching on the fifth illumination source114when the initial setup of the rotating mirrors123and133is completed, operation S113of taking the target object1via the image formation part110and thereby inspecting a particular shape of the target object1, and operation S114of moving the target object1to the setup location when the secondary inspection is completed.

In operation S120, when the target object1is moved to the setup location, the inspection method switches on any one of the first through the fourth illumination sources181a,181b,181c, and181d. In operation S130, the central control unit230verifies whether the selected illumination source is switched on. For example, when the first through the fourth illumination sources181a,181b,181c, and181dare sequentially switched on/off, the central control unit230verifies whether the first illumination source181ais switched on.

Operation S130of verifying, by the central control unit230, whether the selected illumination source is switched on returns to operation S120of switching on any one of the fourth illumination sources181a,181b,181c, and181dwhen the selected illumination source is not switched on by verifying whether the fourth illumination sources181a,181b,181c, and181dare sequentially selected and switched on or off. Conversely, when the selected illumination source is switched on, the inspection method moves a grating element corresponding to the selected illumination source by 1/N pitch by moving the grating board183when the selected illumination source is switched on in operation S140. For example, when the first illumination source181ais switched on, the inspection method moves the first grating element182acorresponding to the selected first illumination source181aby 1/N pitch.

In operation S150, when the grating element is moved, the image formation part110takes a pattern image reflected from the target object1. In operation S160, the central control unit230verifies whether the grating element is an Nth pitch movement while acquiring the pattern image. Operation S160of verifying whether the grating element is the Nth pitch movement is to utilize an N bucket algorithm when inspecting a 3D shape of the target object1. Operation S160of verifying, by the central control unit230, whether the grating element is the Nth pitch movement returns to operation S140of moving the grating element corresponding to the selected illumination source by 1/N pitch when the Nth pitch movement of the grating element is unfinished. Conversely, when the grating element is the Nth pitch movement, the inspection method obtains a phase map using the pattern image taken in each movement in operation S170.

In operation S180, when the phase map is obtained, the central control unit230verifies whether first through fourth phase maps are obtained. For example, when the pattern image is taken via the first illumination source181aand the first grating element182aand thereby the phase map is obtained, the central control unit230stores the obtained phase map as a first phase map. Next, while sequentially switching on/off the second through the fourth illumination sources181b,181c, and181dafter switching off the first illumination source181a, the central control unit230obtains second through fourth phase maps according thereto, and emits the pattern illumination toward the multi-directions of the target object1. Next, the central control unit230takes a pattern image reflected from the target object1, obtains the first through the fourth phase maps, and verifies the result thereof. In this instance, operation S180of verifying, by the central control unit230, whether the first through the fourth phase maps are obtained returns to operation S120of switching on any one of the first through the fourth illumination sources181a,181b,181c, and181dto obtain the first through the fourth phase maps when all the first through the fourth phase maps are not obtained. Conversely, when the first through the fourth phase maps are obtained, the central control unit230calculates an integrated phase map in which noise is removed using the obtained first through the fourth phase maps, and calculates an integrated height map using the integrated phase map, and thereby inspects a 3D shape of the target object.

Operation S190of inspecting the 3D shape of the target object1includes operation S191of calculating, by the central control unit230, the integrated phase map in which noise is removed using the first through the fourth phase maps when the first through the fourth phase maps are obtained, operation S192of calculating, by the central control unit230, the integrated height map using the calculated integrated phase map, and operation S193of inspecting, by the central control unit230, the 3D shape of the target object1using the calculated integrated height map.

A multi-directional projection type moire interferometer and an inspection method using the same according to the present invention may remove a complex shadow region according to various types of shapes of a target object. Also, since the multi-directional projection type moire interferometer can be constructed in compact by readily changing a projection direction of a pattern illumination via a rotating mirror part to emit an illumination pattern toward a target object, and controlling a movement of a grating board by installing a plurality of grating elements on the grating board, a manufacturing cost can be reduced.