KR100662576B1 - Optical device testing apparatus and testing method using the same - Google Patents

Abstract

An apparatus and a method for inspecting an optical device are provided to measure the deformation of the optical device. An apparatus for inspecting an optical device includes a heterodyne laser(10), a phase changing section(30), a polarization section(40), a light collecting section(50), an optical diode(60), and a signal processing section(70). The heterodyne laser irradiates light to the optical device. The phase changing section removes noise by changing the phase of the light irradiated from the heterodyne laser. The polarization section polarizes the light passed through the optical device to a predetermined direction. The light collecting section collects the polarized light. The optical diode converts the collected light to an electrical signal. The signal processing section processes the electrical signal.

Description

Inspection device and inspection method of optical device {OPTICAL DEVICE TESTING APPARATUS AND TESTING METHOD USING THE SAME}

1 is a schematic diagram of an optical device inspection apparatus according to an embodiment of the present invention,

2a to 2c are views for explaining a phase change unit according to an embodiment of the present invention,

3 is a view for explaining a polarizer according to an embodiment of the present invention;

4 is a cross-sectional view of an optical device displayed by the inspection method according to an embodiment of the present invention,

5 is a control flowchart illustrating a test method according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: laser 20: light amount control unit

30: phase change unit 40: polarizer

50: condenser 51: condenser lens

53: optical fiber 60: photodiode

70: signal processing unit 80: display unit

90: stage 100: optical device

The present invention relates to an optical device inspection apparatus and an inspection method, and more particularly, to an inspection device and an inspection method of an optical device that can produce birefringence and thickness deformation in the manufacturing process.

Plate-shaped optical devices such as glass substrates used in liquid crystal display devices undergo various inspection processes in the manufacturing process. These inspection items include bubbles, wounds, defects, contamination, foreign matter adhesion, etc. generated inside and outside the optical device, and the items are measured to evaluate and improve the quality of the optical device.

The quality of the optical device is determined depending on internal factors such as horizontal polarization degree distribution in addition to the external factors described above. As display devices become larger and larger, internal stresses that may occur during manufacturing are closely related to the quality of optical devices. The stress generated inside or outside the optical device causes birefringence of light passing through the optical device, and this birefringence deepens the lateral modulation of the optical device, thereby decreasing the uniformity of the light passing therethrough. In addition, when the thickness distribution of the plate-shaped optical device as well as the birefringence is not constant, it becomes a factor of degrading the brightness of the image and the reproduced image quality.

Therefore, not only the measurement of various defects of the optical device but also the inspection of the birefringence and the thickness change at each position of the optical device due to residual stress caused by heat and pressure should be performed. However, current optical inspection apparatus can not do this, or even if it can be performed, there is a problem that takes a lot of time and involves a complicated process.

Accordingly, it is an object of the present invention to provide an optical inspection apparatus and an optical inspection method capable of measuring the degree of birefringence and thickness deformation of a plate-shaped optical device.

The object is a heterodyne laser for emitting light to the optical device according to the present invention; A phase change unit which removes noise by changing a phase of light emitted from the heterodyne laser; A polarizer which polarizes the light passing through the optical device in a specific direction; A condenser for condensing polarized light; A photodiode for converting the collected light into an electrical signal; It is achieved by the inspection device of the optical device including a signal processor for processing the electrical signal.

The heterodyne laser emits two lights with different polarization directions and different frequencies at the same time. Each light has a polarization component such as noise in a direction perpendicular to its polarization direction.

It may further include a light amount adjusting unit for adjusting the amount of light emitted from the heterodyne laser, the light amount adjusting unit includes an optical attenuator or an optical density filter for filtering the light density to a desired amount to reduce the amount of light emitted ( neutral density filter) may be used.

The phase change unit may be a quarter wave plate (QWP), and the phase change unit may delay a phase of a specific polarization direction of the emitted light by λ / 4.

The condenser may include a condenser lens; Including the optical fiber for transmitting the light collected by the condenser lens serves to transmit the polarized light through the polarizer to the photodiode.

The signal processor filters the electrical signal and converts and processes a plurality of electrical signals into a specific signal.

In addition, by including a display unit for displaying the data processed by the signal processor to enable the user to easily grasp and use information on the properties of the optical device.

It is preferable to further include a stage for supporting the optical device to scan the light emitted from the heterodyne laser over the entire surface of the optical device, and to move the optical device relative to the heterodyne laser.

On the other hand, the object, according to the present invention, the light emitting step of emitting light; A phase change step of removing noise by changing the phase of the emitted light; A polarization step of polarizing the light passing through the optical device in a specific direction; A light condensing step for condensing the polarized light; A signal conversion step of converting the collected light into an electrical signal; A signal processing step of processing the electrical signal; It is also achieved by an inspection method of an optical device including a display step of displaying the processed data.

Preferably, the light is emitted from a heterodyne laser.

Between the light output step and the phase change step, it may further comprise a light amount adjusting step for adjusting the amount of light emitted, the light amount is adjustable in the laser can be optionally provided.

In order to remove noise, the phase shifting step preferably delays the phase of the emitted light in a specific polarization direction by λ / 4.

The signal processing step may be processed in software.

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

1 is a schematic view of an optical device inspecting apparatus according to an embodiment of the present invention, as shown in the optical device inspecting apparatus is a laser 10, a light amount adjusting unit 20, a phase change unit 30, a polarizer ( 40, a light collecting unit 50, a photodiode 60, a signal processing unit 70, a display unit 80, and a stage 90 for supporting the optical device 100.

The laser 10 is a light source that emits light to the optical device 100. In the present invention, a Zeeman laser, which is a type of heterodyne laser, is used. Heterodyne lasers are two light beams having different polarization directions perpendicular to each other and having different frequencies at the same time, and are similar but not identical in frequency. In this embodiment, the wavelength of the first light E1 is about 632.8 nm, and the second light E2 is about 632.5 nm.

FIG. 2A illustrates a polarization state of the initial light emitted from the laser, and the light emitted from the heterodyne laser is perpendicular to the first light E1 and the first light E1 polarized in the y-axis direction. It consists of the 2nd light E2 polarized in the axial direction. All components referring to the polarization component described below, including the first light E1 and the second light E2, are vectors having a direction and a magnitude.

Both the first light E1 and the second light E2 exhibit a slightly elliptical polarization state in the initial state. That is, although the first light E1 is light polarized in the y-axis direction, there is about a polarization component in the x-axis direction. Similarly, the second light E2 also has a polarization component of about b in the y-axis direction in addition to B, which is the x-axis polarization component. Thus, it can be said that the heterodyne laser is characterized by including two perpendicular light having an elliptical polarization component.

The light emitted from the laser 10 is adjusted in the amount of light in the light amount control unit 20. The light amount adjusting unit 20 is located at the head of the laser 10, and an optical attenuator for reducing the amount of emitted light or a light density filter for filtering the light density to a desired amount is used. .

The light amount adjusting unit 20 is not necessarily a component required in the present embodiment, and the light amount may be selectively provided because the light amount is adjustable when the light is emitted from the laser 10.

The phase change unit 30 is emitted from the laser 10 to change the phase of the light whose amount is adjusted in the light amount adjusting unit 20. As described above, the heterodyne laser emits light (A, B) having polarization directions perpendicular to each other, and each of the light components (a, b) such as noise in a direction perpendicular to its polarization directions (A, B). Has These components (a, b), such as noise perpendicular to the polarization components (A, B), become a factor in generating residual current when collected through the optical device 100. Due to this residual current, the state of the optical device 100 cannot be accurately detected, so the phase change unit 30 adjusts the phase of the light to change the polarization state of the light to a straight line instead of an ellipse.

A detailed description with reference to FIGS. 2B and 2C is as follows. FIG. 2B is a view showing that the phase of the light is delayed by about [lambda] / 4 in the phase change unit 30, and FIG. 2C is a view showing the polarization state of the light passing through the phase change unit 30. As shown in FIG.

In FIG. 2B, only the first light E1 is shown for convenience of description, and the following description is similarly applied to the second light E2. As shown, the first light E1 has a y-axis polarization component A and an x-axis polarization component a. The x-axis polarization component (a) having a smaller amplitude than the amplitude of the y-axis polarization component (A) acts as noise of the overall emitted light. Since the y-axis polarization component (A) and the x-axis polarization component (a) have a phase difference of about λ / 4, the phase change unit 30 delays the phase of any one of the two polarization components to increase the amplitude of the two polarization components. Match the position to be zero. In this embodiment, the y-axis polarization component (A) is delayed by about [lambda] / 4, and the effect is as if the x-axis polarization component (a) is advanced by about [lambda] / 4. As a result, the phase-changed x-axis polarization component (a ') and y-axis polarization component (A) have the maximum and minimum amplitude at the same position with respect to the traveling direction (z-axis).

The phase change unit 30 according to the present embodiment uses a quarter wave plate (QWP) for changing the phase of a specific polarization component by λ / 4, and removes noise components.

As described above, the polarization state of the light whose phase is changed can be seen that the polarization axis is shifted by a predetermined angle in both the first light E1 ′ and the second light E2 ′ as shown in FIG. 2C. In addition, it can be seen that the polarization states of the first light E1 ′ and the second light E2 ′ are no longer elliptical, but are straight lines perpendicular to each other. This means that the noise component that can be measured by the residual current is removed.

The light whose phase is changed by the phase change unit 30 is irradiated to the plate-shaped optical device 100. The optical device 100 may be a glass substrate mainly used for a thin film transistor substrate or a color filter substrate of a liquid crystal display.

The stage 90 supports the optical device 100 and moves relative to the light emitted from the laser 10. The stage 90 is operated by a driver and a controller not shown, and moves the optical device 100 so that all areas of the optical device 100 can be scanned by the emitted light.

Recently, with the increase of the size of the display device, the glass substrate is also getting larger and correspondingly, it is necessary to accompany the reliability test of the glass substrate. In addition, in order to meet the increased demand for image quality of consumers, a strict inspection of basic optical devices is required. In this embodiment, the birefringence degree and thickness change of the optical device 100 may be measured in a non-contact manner by irradiating the front surface of the optical device 100 with the light emitted from the laser 10.

Light passing through the optical device 100 contains information about the state inside the optical device 100 changed by heat and pressure. Although the inspection device 1 of the optical device according to the present embodiment is for measuring the birefringence or the thickness change inside the optical device 100, the inspection item is not limited thereto. In other words, it may include matters related to defects, color changes, etc., which are exposed on the outer surface of the optical device 100, or may include other inspection items that can be known through light. Unwanted stress may occur due to heat and pressure in the manufacturing process of the optical device 100, which causes a birefringence and a change in thickness of the optical device 100. The distribution of birefringence and thickness change may appear differently depending on the strength of the stress or the area of the optical device 100, and the light passing through the optical device 100 contains all of this information.

The polarizer 40 passes through the optical device 100 to polarize the light containing information on the internal state of the optical device 100 in a specific direction. As shown in FIG. 3, the first light E1 ′ passing through the phase change unit 30 is changed to the third light E3 by the internal environment while passing through the optical device 100. When the third light E3 is separated into a unit vector, it is divided into the component E1 'which has passed through the phase change unit 30 and the component D added or changed due to the influence of the inside of the optical device 100.

The light of this modified component (D) is extracted by the polarizer 40. The polarization direction of the polarizer 40 is not fixed to one, but may be adjusted according to the light component to be extracted in the process of repeating the inspection process.

The condenser 50 includes a condenser lens 51 and an optical fiber 53, and condenses the light polarized by the polarizer 40. The condenser lens 51 is preferably a lens capable of collecting light, such as a convex lens, and the light collected by the condenser lens 51 is transmitted to the photodiode 60 through the optical fiber 53.

The photodiode 60 converts the quantitative light transmitted from the optical fiber 53 into an electrical signal. The photodiode 60 is an electrical element that causes a current to flow when light is received by the light-emitting diode. In this embodiment, the electrical signal corresponds to a current. The photodiode 60 generates a current having a different magnitude according to the amount of light transmitted, and the signal processor 70 generates a current having a different amplitude, frequency, or the like according to the information according to the birefringence and the thickness change in the optical device 100. ). The electrical signal is not limited to the current and may be anything that can be utilized as data for analyzing the light passing through the optical device 100.

The signal processing unit 70 processes the electrical signal transmitted from the photodiode 60 to change it into data that can be utilized by the user, and displays it on the display unit 90. First, the signal processor 70 separates mixed information on birefringence and thickness change, and filters the electrical signal to a predetermined frequency or a specific region in order to extract each information. This filtering process is performed by a general method of qualitatively or quantitatively analyzing and data-forming an electrical signal, which is a well-known method and description thereof is omitted.

The signal processor 70 is generally implemented in one logic program and implemented in software. Alternatively, the signal processor 70 may be provided as a single chip integrally or electrically connected to the photodiode 60.

The display unit 80 displays the data processed by the signal processor 70 so that the user can visually grasp the data. The display unit 80 may display a table or a graph of birefringence degree and thickness change for each position of the optical device 100, and may display information on the degree of stress in the optical device 100.

4 is a cross-sectional view of the optical device displayed by the inspection method according to an embodiment of the present invention, which shows the thickness and the degree of stress of the optical device 100 displayed on the display unit 80. In principle, the top and bottom surfaces of the plate-shaped optical device 100 should be parallel to each other, but the cross section shown as a result of the data processing shows a curve formed with a peak and a valley. Since the stress inside the optical device 100 is not constant, the thickness of the optical device 100 also changes with the stress.

Although not shown, it is also possible to display data on the birefringence on the display unit 80. The birefringence shows a change pattern independent of the thickness of the optical device 100, but the birefringence measurement amount is about λ / 4 with respect to the thickness change amount. Similar to the shape when delayed.

5 is a control flowchart illustrating a test method according to an embodiment of the present invention.

First, the laser 10 emits light for inspection of the optical device 100 (S10), and then adjusts the amount of the emitted light by using a light amount adjusting unit 20 such as a light attenuator or a light density filter ( S20).

The light emitted from the laser 100 includes two lights having polarization directions perpendicular to each other, and each light has an elliptical polarization shape due to the polarization component perpendicular to its polarization direction. The polarization component that makes the polarization form elliptical acts as noise when converted into an electrical signal through the photodiode 60. Therefore, light is passed through the phase change unit 30 to remove such noise and to make a linear polarization state.

The polarization component of the light is delayed by about [lambda] / 4 by the phase change unit 30 (S30), and the light whose phase is changed has a linear polarization state in which the polarization directions are perpendicular to each other. The light whose phase is changed is scanned while scanning the entire area of the optical device 100 (S40), and contains information about the internal environment of the optical device 100. The light contains information on the birefringence and the thickness change of the optical device 100, and the light containing this information is polarized in a specific direction (S50). The polarized light through the polarizer 40 may extract light components with respect to specific information required by the user.

Then, the light collected and collected by the condenser lens 51 (S60) is input to the photodiode 60 via the optical fiber 53. The photodiode 60 converts the received light into an electrical signal, generally a current value (S70), and transmits the signal to the signal processor 70 by varying the magnitude of the current according to the amount of light received.

The signal processor 70 extracts and processes the electrical signal transmitted from the photodiode 60 as data on birefringence and thickness change by filtering at various frequencies or specific bands (S80). The extracted information is displayed on the display unit 80 in a table or graph that can be easily identified by the user (S90).

Through this inspection method, the properties of the optical device 100 can be inspected easily and quickly without being in contact with the optical device 100.

Although some embodiments of the invention have been shown and described, one of ordinary skill in the art would appreciate the birefringence and thickness variations of optical devices in a non-contact manner without departing from the principles or spirit of the invention. It will be appreciated that the present embodiment, which can be examined, can be modified. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, the present invention provides an optical inspection apparatus and an optical inspection method capable of measuring the degree of birefringence and thickness deformation of a plate-shaped optical device.

Claims (15)

In the inspection device of the optical device, A heterodyne laser for emitting light to the optical device; A phase change unit which removes noise by changing a phase of light emitted from the heterodyne laser; A polarizer which polarizes the light passing through the optical device in a specific direction; A condenser for condensing polarized light; A photodiode for converting the collected light into an electrical signal; Optical device inspection apparatus comprising a signal processor for processing the electrical signal. delete The method of claim 1, The heterodyne laser is an optical device inspection apparatus, characterized in that the laser. The method of claim 1, Optical device inspection apparatus further comprises a light amount control unit for adjusting the amount of light emitted from the heterodyne laser. The method of claim 1, And the phase change unit is a quarter wave plate (QWP). The method of claim 1, And the phase change unit delays the phase of the emitted light in a specific polarization direction by λ / 4. The method of claim 1, The condenser is, A condenser lens; Optical device inspection apparatus comprising an optical fiber for transmitting the light collected by the condensing lens. The method of claim 1, And the signal processor filters the electrical signal. The method of claim 1, And a display unit for displaying the data processed by the signal processor. The method of claim 1, And a stage for supporting the optical device and relatively moving the optical device with respect to the heterodyne laser. In the inspection method of an optical device, A light emitting step of emitting light from the heterodyne laser; A phase change step of removing noise by changing the phase of the emitted light; A polarization step of polarizing the light passing through the optical device in a specific direction; A light condensing step for condensing the polarized light; A signal conversion step of converting the collected light into an electrical signal; A signal processing step of processing the electrical signal; And a display step of displaying the processed data. delete The method of claim 11, Between the light output step and the phase change step, The optical device inspection method further comprises a light amount adjusting step of adjusting the amount of light emitted. The method of claim 11, And the phase shifting step delays the phase of the emitted light in a specific polarization direction by λ / 4. The method of claim 11, The signal processing step is characterized in that the software is processed.

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