KR100726459B1 - 3d shape measuring apparatus - Google Patents

Abstract

A three dimensional shape measuring apparatus is provided to prevent spatial phase transition and vibration generated when a two dimensional sensor, thereby dealing with problems caused by external environment. A three dimensional shape measuring apparatus includes a light source(10), a first mirror(20), a phase adjustment part(50), and a single dimensional array sensor(60). The light source emits light. The first mirror reflects the emitted light to form a reference light. The phase adjustment part divides the reflected light into four parts and adjusts a phase difference of the divided lights integer times of 1/4. The single dimensional array sensor receives each light in a single straight line. The three dimensional shape measuring apparatus further includes an optical guide part(40). The optical guide part guides the light emitted from the light source to the first mirror and a measured body(30), and induces the light reflected by the first mirror and the measured body to the phase adjustment part.

Description

3D shape measuring device {3D SHAPE MEASURING APPARATUS}

1 is a schematic view for explaining a conventional method for scanning a subject,

2 is a schematic view for explaining a method of scanning a subject according to an embodiment of the present invention,

3 is a schematic diagram of a three-dimensional shape measuring apparatus according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: light source 20, 54: mirror

30: subject 40: light induction part

41, 55: polarization splitter 50: phase control unit

51: lambda / 2 wavelength plate 52: light splitter

42, 43, 53: λ / 4 wavelength plate

60: 1-dimensional lane sensor

The present invention relates to a three-dimensional shape measuring apparatus, and more particularly to a three-dimensional shape measuring apparatus using a one-dimensional array scan.

A three-dimensional shape measuring device is used to form an interference pattern by irradiating light of a certain shape on the surface of an object to be inspected (hereinafter referred to as an object), and to obtain information about the height of the object surface by measuring and analyzing the interference pattern. Means the device. Such a measuring method is widely used in the medical and industrial fields because a three-dimensional shape of a subject can be easily obtained.

In general, after inspecting the subject with a two-dimensional sensor, three-dimensional shape information is obtained through a known analysis method. 1 is a view for explaining a three-dimensional shape measurement using a two-dimensional sensor according to the prior art, after capturing an image through the two-dimensional sensor 100 in order to obtain the three-dimensional shape information of the entire object 200 Repeat the process of moving, stopping and moving the sensor. As shown in the figure, the two-dimensional sensor 100 stops, photographs the subject, moves in the direction of the arrow, and enters the image again. Therefore, there is a section where the image pickup is stopped in the middle of the measurement of the image. As a result, there is a problem in that it takes quite a long time to inspect a semiconductor or a large flat panel display.

An interferometer is used because the interference fringe is used as described above to obtain information about the three-dimensional shape. As the interferometer, a piezo interferometer for three-dimensional information of a large substrate, a Michelson interferometer for a small subject, and the like are used. In order to shift the phase of the obtained interference fringe, a piezo element or a phase delay device is used. Since the phase shift method requires multiple sequential sensing, there is a problem in that there is a time difference between each frame and is vulnerable to external vibration. The problem vulnerable to external vibration can be solved through only one parallel sensing, not sequential sensing of phase shift interference fringes. Although there is a parallel sensing method using a two-dimensional array sensor, since it is based on a two-dimensional array sensor, a process of moving and stopping the aforementioned sensor is required, which may be insensitive to vibration, but in three-dimensional high-speed measurement Has a limit.

Accordingly, it is an object of the present invention to provide a three-dimensional shape measuring apparatus capable of measuring a three-dimensional shape of a subject more quickly by using a one-dimensional array scan.

According to the present invention, there is provided an apparatus for measuring a three-dimensional shape of a subject, comprising: a light source for emitting light; A mirror for reflecting the light emitted to form the reference light; A phase adjusting unit which divides the reference light and the light reflected from the subject into four parts and adjusts the phase difference of each divided light by an integer multiple of λ / 4; This is accomplished by a three-dimensional shape measuring instrument comprising a one-dimensional array sensor which receives each divided light on one straight line.

The phase adjusting unit includes: a half-wave plate for delaying a phase of one component of the reference light and the light reflected from the subject by λ / 2; A light splitter separating the light emitted from the half-wave plate in a first direction and a second direction; A first polarization splitter that separates the light traveling in the first direction into light in a polarization state perpendicular to each other; A λ / 4 wave plate for retarding the phase of the light traveling in the second direction by λ / 4; And a second polarization splitter that separates the light emitted from the λ / 4 wavelength plate into light having a polarization state perpendicular to each other. If the reference light and the light reflected on the subject cause interference, the phase controller delays and divides the phase of the light containing the interference information.

The light guide unit may further include a light induction unit configured to guide light emitted from the light source to the mirror and the subject, and to guide light reflected from the mirror and the subject to the phase adjusting unit. This is to spatially separate the light emitted from the light source, provide it to the mirror and the subject, and then gather the light provided to the mirror and the subject back together to induce interference of the reflected light, respectively.

The light guide portion may include a polarization splitter, and a λ / 4 wave plate provided between the polarization splitter, the mirror, and the subject. If the light emitted from the light source is in a linearly polarized state, the light having a vertical polarization state is separated from each other by a polarization splitter. If the light emitted from the light source is natural light or circularly polarized light, various optical devices for controlling the polarization state of light between the light source and the polarization splitter may be used.

The phase adjuster may include an interferometer and a spatial phase divider for spatially shifting a beam passing through the interferometer. That is, the phase control unit is possible in a variety of known configurations are not limited to the embodiment of the present invention. It is also possible to use a spatial phase shift optical device using a hologram.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

2 and 3 are views for explaining a three-dimensional shape measuring apparatus according to an embodiment of the present invention, Figure 2 is a view for explaining a method of scanning a subject, Figure 3 is a three-dimensional according to the present embodiment A schematic diagram of the shape measuring device is shown.

As shown in FIG. 2, the 3D shape measuring apparatus 60 according to the present exemplary embodiment captures images by moving and scanning on a subject 30 to be inspected. The imaging direction is similar to the conventional one shown in Fig. 1, and the scanning direction is freely changeable.

Conventionally, a three-dimensional shape measuring device using an interferometer using a two-dimensional array sensor takes a lot of time in the process of repeating the movement and stop, but when using the one-dimensional array sensor 60 as in this embodiment, Since it omits, the 1-dimensional array sensor 60 should just move on the to-be-tested object 30 at a predetermined speed. When the one-dimensional array sensor 60 according to the present embodiment is used, the imaging time may be reduced by 10 times or more. In addition, as described below, the three-dimensional shape measurement according to the present embodiment has an advantage of not being affected by external vibration since the spatial phase transition is made.

The object 30 is a semiconductor substrate or a flat panel display substrate, and the object 30 is not limited to a specific object.

Hereinafter, a 3D shape measuring apparatus will be described in detail with reference to FIG. 3.

The three-dimensional shape measuring apparatus includes a light source 10 that emits light, a first mirror 20 that reflects the emitted light to form a reference light, a reference light, and light reflected from the subject 30. It is divided into four, and includes a phase adjuster 50 for adjusting the phase difference of each divided light by an integer multiple of 1/4 and a one-dimensional array sensor 60 for receiving each divided light on a straight line. In addition, the three-dimensional shape measuring apparatus guides the light emitted from the light source 10 to the first mirror 20 and the object 30, and phase-control the light reflected from the mirror 10 and the object 30 It further includes a light guide portion 40 to guide the portion (50).

The light source 10 preferably uses a laser having high uniformity and high light efficiency. In general, since the laser provides a beam that is polarized in a specific direction, when using a laser to be described later, the light from the light source 10 is transmitted through the first polarization splitter 41 to the first mirror 20 and the object 30. It is easy to separate into.

A spatial filter 12 and a collimator lens 13 are formed between the light source 10 and the light guide portion 40. The spatial filter 12 and the collimator lens 13 allow the light from the light source 10 to travel in parallel without spreading in all directions.

The light guide portion 40 includes first and second λ / 4 wave plates provided between the first polarization splitter 41, the first polarizer splitter 41, the first mirror 20, and the object 30, respectively. (42, 43).

The first polarization splitter 41 reflects the polarization having any one optical axis of the light incident from the collimator lens 13 and transmits the polarization perpendicular to the reflected polarization. That is, the first polarization splitter 41 transmits vertical linearly polarized light among incident light, and transmits horizontally polarized light.

According to another embodiment, when non-polarized light is incident, non-polarized light may first be linearly lighted and then separated.

Light passing through the first polarization splitter 41 and passing through the second λ / 4 wave plate 43 is reflected by the first mirror 20, and then passes through the second λ / 4 wave plate 43 to the first polarized light. It enters into the divider 41. When the light is completely reflected in the first flat mirror 20, the reflected beam serves as a reference light that can be compared with the light reflected from the object 30. The horizontally polarized light transmitted through the first polarization splitter 41 passes through the λ / 2 wave plate as a whole by reciprocating the second λ / 4 wave plate 43. When the horizontally polarized light passes the λ / 2 wave plate, the polarized light is polarized. Since the state changes by 90 °, it changes to vertical linearly polarized light. As a result, the changed vertical linearly polarized light is reflected by the first polarization splitter 41 and is incident to the phase adjuster 50.

The beam reflected by the first polarization splitter 41 and reflected by the object 30 through the first λ / 4 wave plate 42 is again passed through the second λ / 4 wave plate 43 by the first polarization splitter ( 41). Similar to the reference light, the polarization state of the object light reflected from the object 30 is changed from horizontal to vertical, and is input to the phase adjusting unit 50 with the surface shape information of the object 30.

When the optical paths from the light guide portion 40 are arranged, light having a polarization state perpendicular to each other emitted from the light source 10 is partially transmitted through the first polarization splitter 41 and partially reflected. The transmitted light is reflected by the first mirror 20 to become the reference light, and the reflected light is incident on the first polarization splitter 41 again as the target light containing the information of the subject 30. Finally, the reference light and the target light in which the polarization states are perpendicular to each other are incident from the light guide part 40 to the phase adjusting part 50.

The phase adjuster 50 separates the half-wave plate 51 for delaying the phases of one component of the reference light and the target light by λ / 2, and the light splitter for separating the light emitted from the half-wave plate 51 in the first direction and the second direction. (52), a second polarization splitter 55a that separates the light traveling in the first direction into light in a polarization state perpendicular to each other, and the third λ / 4 which delays the phase of the light traveling in the second direction by λ / 4. And a third polarization splitter 55b that separates the light emitted from the wavelength plate 53 and the third λ / 4 wavelength plate 53 into light in a polarization state perpendicular to each other. When one wavelength of light is λ, the 180 ° phase difference means λ / 2, and the 90 ° phase difference means λ / 4.

In addition, the phase adjuster 50 may include a second mirror 54a and second and third polarization splitters for guiding the light passing through the third λ / 4 wavelength plate 53 to the third polarization splitter 55b. And third and fourth mirrors 54b and 54c for directing the light separated at 55a and 55b to the primary array sensor 60.

Half-wave plate 51 delays the phase of one of the two coherent linearly polarized light components by lambda / 2 than the other components. That is, the phase of some components of the reference light and the target light incident on the phase adjusting unit 50 is delayed by λ / 2 with respect to the other components. If the optical axis of the reference light is referred to as the x-axis and the optical axis of the target light is the y-axis perpendicular thereto, when the optical axis of the half-wave plate 51 coincides with the x and y-axis at a 45 ° angle, it is perpendicular to the optical axis of the half-wave plate 51. The phase of the phosphorus component is delayed by [lambda] / 2, and a phase delay does not occur in the component that is parallel to the optical axis of the half-wave plate 51. Accordingly, interference between the reference light and the target light due to the phase difference occurs, and the beam passing through the half-wave plate 51 includes light having a phase difference of λ / 2.

Light having a phase difference of λ / 2 is separated in two directions by the light splitter 52. The light splitter 52 quantitatively separates light from each other in a first direction parallel to the incident direction and a second direction perpendicular to the first direction.

The light propagated in the first direction is separated according to the polarization state by the second polarization splitter 55a. A polarization splitter is an optical device that transmits any one of light in which the polarization states are perpendicular to each other and passes the other. The light having the polarization states perpendicular to each other has a phase difference of λ / 2. In other words, light passing through the half-wave plate 51 and having a phase difference of λ / 2 can be separated into, for example, light having a phase of 0 ° and 180 ° by the second polarization splitter 55a. Light having a phase of 0 ° proceeds and is received by the one-dimensional array sensor 60, and light having a phase of 180 ° is reflected by the third mirror 54b and received by the one-dimensional array sensor 60.

Next, the light propagated in the second direction in the optical splitter 52 is delayed by λ / 4 as a whole by the third λ / 4 wave plate 53, and the one-dimensional array is performed by the second mirror 54a. It is guided in the direction in which the sensor 60 is located. Since the phase delay occurs while the light having a phase of 0 ° and the 180 ° light passes through the third lambda / 4 wavelength plate 53, the light having a phase of 90 ° and the light of 270 ° will be changed.

As such, the light having a phase difference of 180 ° and delayed by λ / 4 from the light traveling in the first direction is separated by the third polarization splitter 55b. That is, light having a phase of 90 ° is transmitted to the one-dimensional array sensor 60 by being transmitted in the advancing direction, and light having a phase of 270 ° is reflected by the fourth mirror 54c and received by the one-dimensional array sensor 60. .

A plurality of interference lights having a λ / 4 phase difference sequentially from 0 ° obtained in the above-described configuration is shaped in three dimensions through a known analysis method.

According to another embodiment, the phase adjuster 50 may include a spatial phase divider that spatially shifts the interferometer and the beam passing through the interferometer, and a phase retarder or hologram for phase shift for the interference fringe. It may be implemented in a manner.

According to the present invention, the large-area subject 30 can be quickly scanned by dividing the light interfering with the reference light and the target light into four light having a phase difference and receiving the light by the one-dimensional array sensor 60. This does not cause a risk due to the spatial phase transition that may occur when using the two-dimensional sensor, such as a weak point to vibration, there is an advantage that is easier to cope with the external environment.

Although some embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that the embodiments may be modified without departing from the spirit or spirit of the invention. . It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, according to the present invention, there is provided a three-dimensional shape measuring apparatus capable of measuring a three-dimensional shape of a subject more quickly by using a one-dimensional array scan.

Claims (5)

In the apparatus for measuring the three-dimensional shape of the subject, A light source for emitting light; A mirror for reflecting the light emitted to form the reference light; A phase adjusting unit which divides the reference light and the light reflected from the subject into four parts and adjusts the phase difference of each divided light by an integer multiple of λ / 4; And a one-dimensional array sensor which receives each divided light on one straight line. The method of claim 1, The phase control unit, A half-wave plate for delaying a phase of one component of the reference light and the light reflected from the subject by? / 2; A light splitter separating the light emitted from the half-wave plate in a first direction and a second direction; A first polarization splitter that separates the light traveling in the first direction into light in a polarization state perpendicular to each other; A λ / 4 wave plate for retarding the phase of the light traveling in the second direction by λ / 4; And a second polarization splitter which separates the light emitted from the λ / 4 wavelength plate into light in a polarization state perpendicular to each other. The method of claim 1, And a light guide part for guiding the light emitted from the light source to the mirror and the object and guiding light reflected from the mirror and the object to the phase adjusting part. The method of claim 3, And the light guide portion comprises a polarization splitter, and a λ / 4 wavelength plate provided between the polarization splitter, the mirror, and the object under test, respectively. The method according to any one of claims 1, 3 and 4, The phase adjusting unit includes a spatial phase divider for spatial phase shifting the beam passing through the interferometer and the interferometer.

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