KR20090021977A - System for measuring optics using member with pin-hole and method of measuring the the same - Google Patents

Abstract

An optical parts measure system and a method for the same are provided to be possible for measure aberration of optical parts having high numerical apertures by diffusing numerical aperture of the incident light to a large diameter waveform generation part including a pinhole member. An optical parts measure system comprises a large diameter waveform generation part(100) including a pinhole member(140) expanding numerical aperture of incident light; a sensor(300) delivering the light generated in the large diameter waveform generation part; and an optical parts located between the large diameter waveform generation part and sensor. The large diameter waveform generation part includes the light source providing the incident light and a lens unit amplifying penetrometer of the light.

Description

System For Measuring Optics Using Member With Pin-Hole and Method Of Measuring the The Same}

The present invention relates to an apparatus and method for measuring optical components, and more particularly, to an apparatus and method for measuring aberrations of optical components.

In general, an optical component constitutes an optical system for processing a semiconductor device, and further, each component of the electronic component. Such optical components typically include a lens, and the lens serves to focus a specific light source on the object, thereby processing the object into a desired shape. By the way, the lens constituting the optical system has an aberration characteristic that causes an incomplete focus on the wafer due to its design, processing, or both. Accordingly, it is important to accurately evaluate the aberration of the lens, and various methods for evaluating the aberration of the lens are currently proposed.

Currently, lenses measure aberrations using a phase shifting interferometer (PSI) due to optical path difference. Such a PSI is designed such that light emitted from a light source branches in two directions. The optical component to be measured is placed on either of the two split light paths, and then the two split lights are focused at one point. The light at the focused point has an interferometer, and the light on the plane causes interference with each other, and the aberration is measured by analyzing the interference (interference pattern or shape).

By the way, PSI requires a reference optical system without aberration. Preferably the PSI requires a reference optic having a numerical aperture equal to or greater than the optical component to be measured.

In particular, in order to increase the storage density of information storage devices, a high number of pickup lenses and short wavelength lasers are gradually being used. For example, for a CD, a pickup lens with a 0.45 aperture and a laser (light source) with a wavelength of 780 nm are used, and a pickup lens with a 0.6 aperture and a laser with a wavelength of 655 nm are used for a DVD, and BD (blue disc), which is a next-generation storage medium, is used. ), 0.85 aperture pickup lens and 405nm wavelength laser are used.

As the numerical aperture (caliber) of the pick-up lens used in the information storage medium is gradually increased in this way, the PSI currently used requires an optical component having a larger numerical aperture (caliber). It causes the price to rise.

Therefore, the technical problem of this invention is providing the optical component measuring apparatus which can measure the characteristic of a high aperture optical component, without adding a high aperture lens.

In addition, another technical problem of the present invention is to provide an optical component measuring method by the optical component measuring apparatus described above.

Optical component measuring apparatus of the present invention for achieving the above object of the present invention, a large-diameter waveform generator including a pinhole member for extending the numerical aperture of the incident light, the sensing unit for receiving the light generated by the large-diameter waveform generator The optical component to be measured is located between the large-diameter waveform generating unit and the sensing unit, and provides light passing through the sensing unit to the sensing unit.

Moreover, the measuring method of the optical component which concerns on another aspect of this invention is as follows. First, a method of measuring characteristics of an optical component by an optical component measuring apparatus including a waveform transmitting unit transmitting light emitted from a light source and a sensing unit detecting light provided from the waveform transmitting unit, wherein the optical source and the waveform are measured. A reference parallel optical lens is disposed between the transmitting units, the light source, the reference parallel optical lens, the waveform transmitting unit and the sensing unit are arranged side by side, and the reference data optical information reflecting optical information of the waveform transmitting unit and the sensing unit is reflected. To calculate. Next, after removing the reference parallel light lens, a large diameter expansion unit having a pinhole member and an optical component to be measured are installed between the light source and the waveform transmitting unit, and the measurement data optical information reflecting the optical information of the optical component to be measured is calculated. do. Thereafter, the reference data optical information is removed from the measurement data optical information to obtain pure optical information of the optical component.

By using the pinhole member, the numerical aperture of the light provided from the light source can be extended beyond the numerical aperture of the optical component or more without using a high aperture lens. Since the pinhole member is composed of an opaque layer having a transparent substrate with respect to light and a pinhole formed on the transparent substrate, the pinhole member can be easily manufactured and high cost is not consumed. In addition, the size of the pinhole can be freely set according to the numerical aperture of the optical component to be measured.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

The present invention provides an optical component measuring apparatus and method for generating light (or waveform) whose numerical aperture is expanded by a pinhole member without the need for a lens having a high aperture number. In this embodiment, the pinhole member focuses on the principle of focusing light to the pinhole to diffuse light to increase the transmittance and numerical aperture ("pinhole effect"), thereby expanding the numerical aperture of incident light.

This will be described in more detail with reference to the drawings.

Referring to FIG. 1, the optical component measuring apparatus may include a large diameter waveform generator 100, a waveform transmitter 200, and a detector 300. The optical component 400 to be measured is disposed between the large-diameter waveform generator 100 and the waveform transmitter 200, and the optical component 400 may be, for example, a lens provided in a storage medium.

The large-diameter waveform generator 100 may be configured of a light source 110, an optical fiber 120, a lens unit 130, and a pinhole member 140.

The light source 110 may be, for example, a laser light source. As the light source 110 of the present embodiment, a laser light source of various wavelengths may be used.

The optical fiber 120 is installed between the light source 110 and the lens unit 130 to provide the light provided from the light source 110 to the lens unit 130. The optical fiber 120 may be a single mode optical fiber, and since its diameter has a diameter of 1 to 10 μm, clean light without aberration may be applied to the lens unit 130 without using a spatial filter. Can provide. In addition, since the optical fiber 120 is easily connected to the light source 110 and the lens unit 130, replacing the light source 110 only changes the connection state of the optical fiber 120 without moving the light source 110. Can be achieved.

The lens unit 130 amplifies the transmittance of light to be incident on the pinhole member 400. As described above, the pinhole member 400 outputs light at a wider diffusion angle when the light is focused. Therefore, in order to secure a wider numerical aperture, the transmittance of incident light is amplified by the lens unit 130. The lens unit 130 may be composed of a plurality of lenses 131 and 133. In the present exemplary embodiment, the lens unit 130 may include a collimating lens 131 and a focusing lens 133. These lenses 131 and 133 may be arranged side by side at a predetermined interval.

The pinhole member 140 extends the numerical aperture (caliber) of the light provided from the lens unit 130. As shown in FIG. 2, the pinhole member 140 may be a substrate 141 transparent to incident light, such as a glass substrate, and an opaque layer 143 having a pinhole H on the transparent substrate 141. Can be configured. For example, a gold (Au) layer may be used as the opaque layer 143, and may be formed to have a thickness of about 100 to 300 nm in consideration of its skin depth. The opaque layer 143 may be formed by, for example, evaporation, and the pinhole H may be obtained by partially removing the opaque layer 143.

Herein, the size (diameter) of the pinhole H may be defined by the following equation based on a point-diffraction interferometer (PDI).

<Equation 1>

D in Equation 1 is the size of the pinhole H,? Is the wavelength of incident light, and NA is the numerical aperture.

According to the above equation, it can be seen that the smaller the size of the pinhole H, the larger the waveform of the numerical aperture is generated. For example, when the pinhole H is manufactured to the size of 1/2 of the incident light wavelength, a hemispherical spherical wave can be obtained. By such a formula, the size of the pinhole H can be set in accordance with the numerical aperture (diameter) of the measuring component 400.

In the present embodiment, the pinhole H is formed at 150 to 550 nm, and the pinhole H is formed by, for example, a focused ion beam (FIB) method.

In the drawing, reference numeral 150 denotes light (or waveform of light) having an extended numerical aperture (diameter) generated in the pinhole member 140, and 160 denotes light (or waveform of light when passing through the optical component 400). ). In this case, the light 160 passing through the optical component 400 may be in a distorted state by reflecting optical characteristics, for example, aberration, of the optical component 400.

Meanwhile, the lenses 131 and 133 of the lens unit 130 to improve the transmittance of the incident light may also have aberration. However, even if the waveform of the incident light is distorted due to aberrations of the lenses 131 and 133 constituting the lens unit 130, the pinhole member 140 functions as a kind of low pass filter. The distortion of the waveform of incident light with improved transmittance can be eliminated.

The waveform transmitting unit 200 transmits the light 160 passing through the optical component 400 to the sensing unit 300 without any optical deformation. Here, "optical deformation" means all optical modulations such as deformation, diffraction, and interference due to aberration of traveling light. Relay optics may be used as the waveform transmitter 200 of the present embodiment. As illustrated in FIG. 3, the relay optics may be configured as a pair of lenses 210 and 220 spaced apart from each other by a predetermined distance. These pairs of lenses 210,220 can be, for example, highly accurate achromatic lenses, and a caperian telescope whose optical surfaces (lens surfaces 210a, 220a) are arranged to face each other. It can be arranged in the form of. For example, the optical surface 210a of the lens 210 on which light is incident may have a convex-planer shape, and the optical surface 220a of the lens 200 on which light is emitted. May have a planer-convex form. As the lenses 210 and 220 are disposed to replace the optical surfaces 210a and 220a as described above, the incident parallel light 160 is emitted in an inverted (inverted) form. Reference numeral 160a denotes output light of the waveform transfer unit, that is, inverted incident light. When the pair of lenses 210 and 220 have the same focal length (f1 = f2), light having the same size as the incident light is emitted, and when the focal lengths are different (f1 ≠ f2), the enlarged or reduced size of the incident light is increased or reduced. Can emit light of size.

The detector 300 detects a characteristic of light incident from the waveform transfer unit 200. As the sensing unit 300, a Shack-Hartmann sensor (hereinafter referred to as an SH sensor) may be used in the present embodiment. The SH sensor may be configured as a micro lens array 310 and a charge coupled device (CCD) 320 as shown in FIG. 4. The micro lens array 310 focuses the light provided from the waveform transfer unit 200. The CCD 320 detects light focused from the micro lens array 310 and analyzes information of light incident from the waveform transfer unit 200. "History and principles of Shack-Hartmann wavefront sensing" by Ben C. Platt and Roland Shack for this SH sensor, J. Refrac. Surg 17, S573-577 (2001).

This SH sensor detects the characteristics of the light incident by the following mechanism.

Referring to FIG. 5A, the reference light 500 is incident on the micro lens array 310 of the SH sensor. The reference light 500 is focused by the micro lens array 310 and reaches the CCD 320. 5B shows the surface of the CCD 320 where the reference light 500 is focused. Reference numeral 510 in FIG. 3 denotes a reference light point focused on the CCD 320.

Meanwhile, referring to FIG. 6A, measurement light 500a (eg, light passing through an optical component) is incident on the micro lens array 310 of the SH sensor. The measurement light 500a is focused by the micro lens array 310 and reaches the CCD 320. FIG. 6B shows the surface of the CCD 320 in which the measurement light 500a is focused, and 510a in the figure shows the focused measurement light point. The measurement light point 510a of FIG. 6B is deviated by a predetermined distance from the reference light point 510 by an optical characteristic of the optical component 400, for example, aberration. The CCD 320 measures the distance difference between the measurement light point 510a and the reference light point 510, and measures the characteristic of the optical component 400, for example, aberration, from the distance difference.

Such an optical component measuring apparatus is mounted on the rail 600 as shown in FIG. As illustrated in FIG. 7, the large-diameter waveform generating unit 100, the waveform transmitting unit 200, the sensing unit 300, and the optical component 400 to be measured, which constitute the optical component measuring apparatus, are first and second, respectively. And third and fourth conveying members 610a, 610b, 610c, and 610d, and the conveying members 610a, 610b, 610c, and 610d are mounted on the rail 600 to provide the optical component measuring device. Reposition each component on the rail 600. In addition, the third conveying member 610c supporting and fixing the sensing unit 300 and the fourth conveying member 610d supporting and fixing the measuring optical component 400 have the measuring optical component 400 generating the large-diameter waveform. The pinhole member 140 may move with five degrees of freedom so as to be accurately aligned with the pinhole member 140 of the unit 100. In addition, since the components constituting the optical component measuring apparatus are mechanically fixed by the transfer members 610a, 610b, 610c, and 610d disposed on the rail 600, alignment between the components is easy.

In addition, although not shown in the drawings, the transfer members 610a, 610b, 610c, and 610d may be inserted into the protrusions of the rail 600 and may be fixed by fastening members, for example, screws.

Such driving of the optical component measuring apparatus according to the exemplary embodiment of the present invention is as follows.

First, the optical component 400 to be measured is inserted between the large-diameter waveform generator 100 having the fine pinhole member 140 and the waveform transmitter 200.

When light is irradiated from the light source 110, the optical fiber 120 of the large-diameter waveform generator 100 transmits the incident light to the lens unit 130. The lens unit 130 focuses the incident light and transmits the incident light to the pinhole member 140. The pinhole member 140 extends the numerical aperture (caliber) of incident light. As described above, since the pinhole H has a characteristic of diffusing incident light, the pinhole member 140 having the pinhole H receives the incident light by the numerical aperture (diameter) of the optical component 400. Expand to fit.

The incident light having the numerical aperture extended passes through the optical component 400 and its waveform is distorted according to the optical characteristics of the optical component 400, for example, aberration. The distorted light is transmitted to the detector 300 via the waveform transmitter 200. The detector 300 compares an arrival position of light in a steady state with an arrival position of the distorted light, and measures an optical characteristic of the optical component 400, for example, aberration.

On the other hand, the relay optics of the waveform transmission unit 200 said that the optical deformation of incident light is transmitted theoretically, but may be substantially aberration as it is composed of a pair of lenses 210 and 220 having their own aberrations. . As a result, the incident light (the incident light with the expanded diameter) may pass through the waveform transfer part 200, and distortion may occur. For example, when the aberration of the relay optics in which the 45 mm diameter lens was placed 1: 1 using optical design software was measured, the aberration of 0.026 lambda rms was measured at 632.8 nm diameter, and the aberration of 0.015 lambda rms at 405 nm diameter was measured. Was measured. In addition, since the sensing unit 300 also includes the micro lens array 310, the sensing unit 300 may have its own aberration.

This embodiment provides an error correction apparatus as shown in FIG. 8 to measure the aberration components of the waveform transmitter 200 and the detector 300.

The error compensating apparatus may include a light source 110, an optical fiber 120, a reference parallel light lens 170, a waveform transfer unit 200, and a detector 300. That is, the error correcting apparatus of the present exemplary embodiment installs the reference parallel light lens 170 instead of the lens unit 130, the pinhole member 140, and the optical component 400 to be measured of the optical component measuring apparatus of FIG. 1. The reference parallel light lens 170 may be configured as an optical lens having almost no aberration to measure the degree of distortion by the waveform transmitting unit 200 and the sensing unit 300. In this embodiment, the reference parallel optical lens 170 uses three glass lenses having a numerical aperture of about 0.1 and having an aberration of about 0.009 lambda rms in a 35 mm diameter region. The error compensator may be disposed on a rail like the optical component measuring device to achieve an accurate alignment.

Pure aberration measurement method of an optical component using such an error correction device is as follows.

Referring to FIG. 9, when incident light is provided from the light source 110, the incident light passes through the optical fiber 120 and the reference parallel light lens 170 and is transmitted to the waveform transfer unit 200. At this time, the reference parallel optical lens 170 generates a nearly perfect plane wave, and provides the plane wave to the waveform transfer unit 200 as it is (without distortion). After that, the incident light is transmitted to the sensing unit 300 through the waveform transmitting unit 200, and the sensing unit 300 generates aberration information of the waveform transmitting unit 200 and the sensing unit 300 by the waveform of the transmitted light. Reflected reference data optical information is obtained (S1). The reference data optical information thus obtained is transmitted to wavefront analysis software (not shown).

Thereafter, as shown in FIG. 1, the lens unit 130, the pinhole member 140, and the optical component 400 are inserted instead of the reference parallel optical lens 170, and then the aberration measurement of the optical component 400 is performed. In operation S2, measurement data light information reflecting the aberration of the optical component 400 is obtained.

Next, measurement data optical information is transmitted to the software, and the reference data optical information is removed from the measurement data optical information in the software (S3). That is, since the measurement data optical information is reflected not only the aberration information of the optical component 400 but also the aberration information of the waveform transmission unit 200 and the sensing unit 300, in order to obtain accurate aberration information of the optical component 400. The software removes the reference data information including the aberration information of the waveform transfer unit 200 and the detector 300 from the measurement data optical information. Thereby, the pure component aberration information of the optical component 400 can be obtained. At this time, before measuring the reference data information, it is preferable to preheat 60 to 120 minutes in order to minimize the error of the sensing unit 400 itself.

The optical component measuring apparatus of the present invention diffuses the numerical aperture of incident light by the large-diameter waveform generating unit 100 including the pinhole member 150, thereby providing an optical component having a high number of apertures without requiring a high number of lenses. The aberration can be measured.

In the present embodiment, the optical component measuring apparatus measures the aberration of the optical component, which may be RMS aberration, P-V aberration, spherical aberration, coma, astigmatism, and the like.

In the present embodiment, the light passing through each component constituting the optical component measuring apparatus is referred to as light as a whole, but this may be information in which the waveform of the light or the waveform of the light is reflected.

In addition, various changes can be made without departing from the spirit of the invention.

1 is a view schematically showing an optical component measuring apparatus according to an embodiment of the present invention;

2 is a cross-sectional view of the pinhole member of the optical component measuring apparatus according to the embodiment of the present invention;

3 is a view schematically showing a relay optics which is a waveform transmission unit of an optical component measuring apparatus according to an exemplary embodiment of the present invention;

4 is a view schematically showing a structure of a SH-shack-Hartmann sensor which is a sensing unit of an optical component measuring apparatus according to an exemplary embodiment of the present invention;

5A and 5B are cross-sectional views and a plan view showing the operation of the SH sensor when the reference light is incident on the SH sensor of FIG.

6A and 6B are cross-sectional views and a plan view showing the operation of the SH sensor when the measurement light is incident on the SH sensor of FIG.

7 schematically shows an optical component measuring apparatus mounted on a rail according to an embodiment of the present invention;

8 is a cross-sectional view showing an apparatus for error correction of an optical component measuring apparatus according to an embodiment of the present invention, and

9 is a flowchart illustrating a method for measuring an optical component from which an error is removed according to an embodiment of the present invention.

Claims (12)

A large-diameter waveform generator including a pinhole member extending a numerical aperture of incident light; And It includes a detection unit for receiving the light generated by the large-diameter waveform generator, The optical component to be measured is located between the large-diameter waveform generating unit and the sensing unit, the optical component measuring apparatus for providing the light passing through the sensing unit. The method of claim 1, The large diameter waveform generation unit, A light source providing the incident light, A lens unit for amplifying a transmittance of light incident from the light source; And And the pinhole member extending the numerical aperture of the light provided from the lens unit. The method of claim 2, And an optical fiber for optically connecting the light source and the lens unit. The method according to claim 1 or 2, The pinhole member, A substrate transparent to the incident light; And And an opaque layer formed on the substrate and including pinholes. The method of claim 4, wherein And the size of the pinhole is variable depending on the wavelength of the light source and the numerical aperture of the optical component to be measured. The method of claim 5, wherein The size of the pinhole is determined based on the following equation,

Where D is the size of the pinhole, λ is the wavelength of incident light, and NA is the numerical aperture The method of claim 1, And a waveform transmission unit between the optical component and the sensing unit to transmit light reflecting optical information of the optical component to the sensing unit. The method of claim 7, wherein The waveform transfer unit, An optical component measuring device, which is a relay optics comprising a pair of lenses spaced at regular intervals and arranged to face optical surfaces. The method of claim 1, The detection unit, A micro lens array for focusing the incident light into a plurality of regions, and And a shack hartmann (SH) sensor including a charge coupled device (CCD) for receiving focused light from the micro lens array. Claims [1] A method of measuring characteristics of an optical component by an optical component measuring apparatus including a waveform transmitting unit transmitting light emitted from a light source and a sensing unit detecting light provided from the waveform transmitting unit. Providing a reference parallel light lens between the light source and the waveform transfer unit; Aligning the light source, the reference parallel light lens, the waveform transfer unit and the detection unit side by side, and calculating reference data optical information reflecting optical information of the waveform transfer unit and the detection unit; Removing the reference parallel light lens; Providing a large-diameter extension having a pinhole member and an optical component to be measured between the light source and the waveform transmitting unit, and calculating measurement data optical information reflecting optical information of the optical component to be measured; And And removing the reference data optical information from the measured data optical information to obtain pure optical information of the optical component. The method of claim 10, The reference parallel light lens The optical component measuring method which is a some glass lens. The method of claim 10, And preheating the sensing unit between the step of installing the reference parallel light lens and calculating the reference data light information.

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