KR20180030297A - Characteristics measurement device of micro lens array and characteristics measurement method using the device - Google Patents

Abstract

The present invention provides a characteristics measurement device of a micro lens array and a characteristics measurement method of a micro lens array using the same which improve efficiency and accuracy. According to an embodiment of the present invention, the characteristics measurement method of a micro lens array comprises: a step of arranging a light source to output a beam in parallel with an optical axis, a target unit, a comparison lens, and a first measurement unit in order; a step of outputting a beam from the light source; a step where the beam sequentially passes through the target unit and the comparison lens and passes a first focus where a focus is formed to enter the first measurement unit to project a first image of the target unit onto the first measurement unit; a step of measuring a size of the first image by the first measurement unit; a step of fixing a first micro lens array between the comparison lens and the first measurement unit to arrange the first micro lens array; a step of outputting the beam from the light source again; a step where the beam sequentially passes through the target unit, the comparison lens, and the first micro lens array and passes a second focus where a focus is formed to enter the first measurement unit to project a second image of the target unit onto the first measurement unit; a step of measuring a size of the second image by the first measurement unit; and a step of using a first focus distance where the first focus of the comparison lens is formed, the size of the first image, and the size of the second image to obtain a distance moving from the first focus to the second focus.

Description

TECHNICAL FIELD [0001] The present invention relates to a device for measuring a characteristic of a microlens array, and a method for measuring a characteristic of a microlens array using the device. [0002]

The present invention relates to a device for measuring the characteristics of a microlens array and a method for measuring the characteristics of a microlens array using the device, and more particularly to a device for measuring a characteristic of a microlens array using an optical device and a characteristic of a microlens array using the device And a measurement method.

A micro lens array is used to collect light in various display devices applied to portable devices, installation devices, augmented reality devices, and the like, and to improve the utilization efficiency of light. Characteristics of the microlens array such as focal length, anisotropy, birefringence, refractive index, chromatic aberration, and curvature are important factors for determining the performance of the lens . In order to use a microlens array in a display device having pixels in the range of several tens of micrometers (占 퐉), it is necessary to measure these characteristics within an error range of several tens of micrometers (占 퐉) or less. When the error is out of the range of micrometer (占 퐉), even a small value greatly affects the reliability of the display device, and therefore high accuracy is required as a method of measuring the microlens characteristics.

Embodiments provide a method and apparatus for measuring the focal length of a microlens array within an error range of micrometer (占 퐉) and measuring the characteristics of an array of microlenses such as anisotropy, birefringence, refractive index, curvature, This improved microlens array characteristic measuring apparatus and a measuring method using the apparatus are provided.

According to an embodiment of the present invention, there is provided an apparatus for measuring a characteristic of a microlens array, comprising: sequentially arranging a light source, a target portion, a comparative lens, and a first measurement portion for outputting light rays parallel to an optical axis; Outputting a light beam from a light source; The light beam passing through the target portion and the comparison lens in order and passing through a first focal point to be incident on the first measurement portion and projecting a first image of the target portion onto the first measurement portion; Measuring a size of the first image in the first measurement unit; Fixing and arranging a first microlens array between the comparison lens and the first measurement unit; Outputting the light beam again from a light source; The light beam passes through the target portion, the comparison lens, and the first microlens array in order, passes through a second focal point, and is incident on the first measurement portion, Is projected; Measuring a size of the second image in the first measurement unit; Obtaining a distance traveled from the first focus to the second focus using a first focal distance of the first focus of the comparison lens, a size of the first image, and a size of the second image do.

An apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention includes: a light source for outputting a light beam parallel to an optical axis; A target portion on which the light beam is incident; A comparative lens through which the light beam having passed through the target portion is incident; A first microlens array through which the light beam having passed through the comparison lens is incident; And a first measurement unit for measuring the light beam passing through the first microlens array, wherein the comparison lens and the first measurement unit are fixed, and while the focal length of the first microlens array is measured, 1 microlens array does not move, and the first measuring unit measures the size of the projected image of the target portion.

According to the embodiments, the focal length of the microlens array can be measured within an error range in the unit of micrometers (占 퐉), and the characteristics of the microlens array such as anisotropy, birefringence, refractive index, curvature, Can be measured, and microlens array characteristics can be measured with improved accuracy and efficiency. Further, the reliability of the display device to which such a microlens array is applied can be improved.

1 is a view schematically showing an apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention and a method for measuring a focal length of a microlens array using the apparatus.
2 is a view illustrating an experiment result of measuring an image of a target portion in a first measurement unit using an apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention.
3 is a view schematically showing an apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention.
4 is a view schematically showing an apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention.
FIG. 5 is a graph showing the results of an experiment for measuring a light beam incident on a second measurement unit using an apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In addition, since the sizes and thicknesses of the respective components shown in the drawings are arbitrarily shown for convenience of explanation, the present invention is not necessarily limited to those shown in the drawings. In the drawings, the thickness is enlarged to clearly represent the layers and regions. In the drawings, for the convenience of explanation, the thicknesses of some layers and regions are exaggerated.

Also, when a portion such as a layer, a film, an area, a plate, etc. is referred to as being "on" or "on" another portion, this includes not only the case where the other portion is "directly on" . Conversely, when a part is "directly over" another part, it means that there is no other part in the middle. Also, to be "on" or "on" the reference portion is located above or below the reference portion and does not necessarily mean "above" or "above" toward the opposite direction of gravity .

Also, throughout the specification, when an element is referred to as "including" an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

Also, in the entire specification, when it is referred to as "planar ", it means that the object portion is viewed from above, and when it is called" sectional image, " this means that the object portion is viewed from the side.

Hereinafter, an apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention and a method for measuring a focal length of the microlens array using the apparatus will be described in detail with reference to FIGS. 1 and 2. FIG.

1 is a view schematically showing an apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention and a method for measuring a focal length of a microlens array using the apparatus. 2 is a view illustrating an experiment result of measuring an image of a target portion in a first measurement unit using an apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention.

The apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention includes a light source unit 500, a target unit 501, a comparison lens 502, and a first measurement unit 504. The first microlens array 503, which is a characteristic measurement object, may be positioned between the comparison lens 502 and the first measurement unit 504. [

The light source unit 500 outputs a light beam parallel to the optical axis BA of the microlens array characteristic measurement apparatus and is positioned to output a light beam toward the target portion 501. The light source unit 500 may include a collimator that converts divergent light emitted from the point light source into parallel light. A laser may be used for the light source unit 500, and various types of light sources capable of generating a stable output may be used instead of the specific light source.

The target portion 501 is positioned between the comparison lens 502 and the light source portion 500. The target portion 501 may have a size of 5% or more and 500% or less of the diameter of the first microlens array 503, which is an object to be measured. The size of the target portion 501 may be 1 micrometer (μm) or more and 50 mm (mm) or less. The target portion 501 may be a geometric shape such as letters, numbers, symbols, and the like.

The comparison lens 502 is a lens that is known to have a first focal length FLr which is a focal distance and is located between the target portion 501 and the first measurement portion 504. [ The light beam incident on the comparative lens 502 is refracted and the first focus Fr is formed at a position apart from the comparative lens 502 by the first focal distance FLr.

The first microlens array 503 may be positioned between the comparison lens 502 and the first measurement unit 504 as an object to be measured. The first microlens array 503 may be a liquid crystal microlens array for electrically adjusting the light converging characteristics of a liquid crystal. The comparison lens 502 and the first measurement unit 504 may be located at a distance of 50 micrometers (탆) or more and 500 nanometers (nm) or less, of the first microlens array 503.

The light beam output from the light source unit 500 is finally incident on the first measurement unit 504. The first measurement unit 504 measures the characteristics of the incident light beam. The first measurement unit 504 may be a CCD (Charge-Coupled Device) camera.

Hereinafter, a method of measuring the focal length of the microlens array using a microlens array characteristic measuring apparatus will be described. The parallel rays output from the light source unit 500 pass through the target portion 501 and enter the comparison lens 502. First, in the absence of the first microlens array 503, the light beam that has passed through the target portion 501 from the light source portion 500 and is incident on the comparison lens 502 is refracted by the comparison lens 502, The first focal point Fr is formed at a position apart from the first focal distance FLr by a first focal length FLr. The light beam with the first focus Fr continues to be incident on the first measurement unit 504 and the image of the target unit 501 is projected onto the first measurement unit 504. The first measuring unit 504 measures the size (Ir) of the first image of the target portion 501 projected and transmitted through the comparison lens 502 alone. FIG. 2A shows one embodiment of a shape that can be used in the target portion 501. FIG. 2B shows a state in which the light beam outputted from the light source unit 500 passes through the target portion 501 having the shape of FIG. 2A and only the comparison lens 502 penetrates the first measurement portion 504 The image of the target portion 501 projected on the first measurement portion 504 is measured. 2B, it can be seen that the first measurement unit 504 can measure the size (Ir) of the first image of the target portion 501 projected through only the comparison lens 502 .

Next, the first microlens array 503 is positioned between the comparison lens 502 and the first measurement unit 504. The light beam that is output from the light source unit 500 and passes through the target portion 501 and is refracted by the comparison lens 502 is incident on the first microlens array 503 and refracted by the first microlens array 503 And focuses on the second focus Fp as a new focus. The light beam having the second focus Fp continues to be incident on the first measurement unit 504 and the first measurement unit 504 transmits both the comparison lens 502 and the first microlens array 503, 1 Measurement of the size (Ip) of the second image of the target portion 501 projected on the measuring portion 504. 2C shows a state in which the light beam output from the light source unit 500 passes through the target portion 501 having the shape of FIG. 2A and passes through the comparison lens 502 and the first microlens array 503 The image of the target portion 501 projected on the first measurement portion 504 is measured when the first measurement portion 504 is incident on the first measurement portion 504. 2C shows a relationship between the size Ip of the second image of the target portion 501 projected after the comparison lens 502 and the first microlens array 503 are sequentially transmitted in the first measurement portion 504, ) Can be measured.

The distance? 1 obtained by moving the focal distance from the first focus Fr to the second focus Fp can be obtained by comparing the first image size Ir and the second image size Ip obtained as described above.

FLr:? 1 = Ir: Ip (1)

(1) is used to obtain the moved distance? 1, and the first focal length FLr of the comparative lens, which is known by? L = (FLr * Ip) / Ir, (Ir) and the second image size (Ip), which are measured in the first image size (Ir). A plurality of microlens arrays can be measured in this manner and the focal distances between a plurality of microlens arrays can be compared by comparing the moved distances? 1 obtained from the respective microlens arrays with each other.

The focal length of the microlens array is less than 1 millimeter (mm), and when moving the microlens array to match the focus of the microlens array to a specific reference focus, (Mm), and the focal length of the microlens array shifted by 1 to 3 millimeters (mm) corresponds to a level of approximately 500 micrometers (占 퐉). The display device to which the microlens array is applied has pixels of a level of several tens of micrometers (m), and the error of a few hundred micrometers (m) scale which can not move the focal distance to only a few hundred micrometers (m) ([Mu] m) level of pixels. Therefore, it is impossible to move the microlens array precisely to a specific reference focus, and the method of moving the microlens array to measure the focal length of the microlens array is very inaccurate. On the other hand, according to the present invention, the microlens array, which is an object to be measured, is measured while being fixed without being moved, and by using the image size to be projected on the target portion without directly measuring the focal distance on the micrometer (탆) The focal length of the microlens array can be measured.

3, an apparatus for measuring a characteristic of a microlens array according to an exemplary embodiment of the present invention and a method for measuring characteristics of a microlens array using the apparatus will be described in detail. The description of the parts overlapping with the above-described embodiments will be omitted.

3 is a view schematically showing an apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention.

The apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention includes a light source 500, a light beam expander 505, a first light beam splitter 506, a target portion 501, a comparative lens 502, A 1/4 wave plate 601, a rotation 1/4 wave plate 603, and a second measurement unit 604.

The first microlens array 503 as the characteristic measurement object can be positioned between the comparison lens 502 and the first measurement unit 504 and the second microlens array 602 as the characteristic measurement object can be positioned between the 1/4 wavelength And may be positioned between the plate 601 and the rotating quarter wave plate 603. [ The same microlens array may be disposed at the positions of the first microlens array 503 and the second microlens array 602. Specifically, the microlens array to be measured for the focal length can be placed at the position of the first microlens array 503, and the microlens array for measuring the anisotropy can be placed at the position of the second microlens array 602 .

The light beam expanding unit 505 extends the parallel light output from the light source unit 500 and may be omitted according to the embodiment.

The first light beam splitter 506 divides the light beams into a first light ray L1 and a second light ray L2 in the same ratio and proceeds in different directions. The first light beam L1 divided at the same ratio can be refracted at 90 degrees and incident on the target portion 501. The second light beam L2 divided at the same ratio goes straight and passes through the 1/4 wave plate 601 Can be entered. The focal length of the microlens array can be obtained as the first light ray L1 that is refracted by 90 degrees by the first light beam splitter 506 and enters the target portion 501, as in the above-described embodiment.

The 1/4 wave plate 601 has a main axis inclined by 45 degrees and serves to delay the phase difference of incident light by? / 2. The second light beam L2 incident on the 1/4 wave plate 601 passes through the second microlens array 602 with a retardation of? / 2 to enter the rotating quarter wave plate 603, do.

The rotating quarter wave plate 603 has a main axis inclined by 45 degrees and serves to delay the phase difference of the incident second light beam L2 by? / 2. The rotation 1/4 wave plate 603 can rotate 360 degrees and the change of light ray can be measured at all angles while rotating the rotation 1/4 wave plate 603 by 360 degrees.

The second light beam L2 having passed through the 1/4 wave plate 603 is incident on the second measurement unit 604. The second measurement unit 604 may be a CCD (charge-coupled device) camera, a photodiode, or an oscilloscope. A CCD (Charge-Coupled Device) camera or a photodiode measures the intensity of an incident light beam and measures the spatial distribution of the incident light beam. Oscilloscopes can measure the hertz and measure the characteristics of incident light.

Hereinafter, a method of measuring the anisotropy of the microlens array using the microlens array characteristic measuring apparatus will be described.

The second light beam L2 output from the light source unit 500 and divided through the first light beam splitter 506 is incident on the 1/4 wave plate 601. The second light beam L2 incident on the 1/4 wave plate 601 is incident on the second microlens array 602 with a retardation of? / 2. If the light beam output by the light source unit 500 is a circularly polarized light ray, the light ray passing through the 1/4 wave plate 601 is linearly polarized with a retardation of? / 2. The second light beam L2 whose retardation is delayed by? / 2 passes through the second microlens array 602 and is incident on the rotating quarter wave plate 603. [

The second light ray L2 incident on the rotating quarter wave plate 603 is again retarded by? / 2 in phase difference. If the light beam output from the light source unit 500 is a circularly polarized light ray, the light ray passing through the 1/4 wave plate 601 is linearly polarized by retardation by? / 2, and the 1/4 wave plate 603 The phase difference is again delayed by? / 2 and circularly polarized.

The second measuring unit 604 measures the second light beam L2 transmitted through the rotating quarter wave plate 603 and enters the second light ray L2 before passing through the quarter wave plate 601. [ The anisotropy of the second microlens array 602 is measured. If the second microlens array 602 is not provided between the 1/4 wave plate 601 and the 1/4 wave plate 603, the second light beam L2 passes through the 1/4 wave plate 601 and the 1 / Wave plate 603, the retardation is retarded by? / 2 and then the retardation is retarded by? / 2. Therefore, even after passing through the rotation 1/4 wave plate 603, the light passes through the 1/4 wave plate 601 Is measured in the same manner as the second light ray L2 before the above. When the second microlens array 602 is positioned between the quarter wave plate 601 and the rotating quarter wave plate 603 and the second microlens array 602 has anisotropy, A change occurs in the second light beam L2. The anisotropic characteristics of the second microlens array 602 can be measured by measuring the spatial distribution according to the sharpness of the second light ray L2 incident on the second measurement unit 604. Alternatively, the second measurement unit 604 may measure the anisotropic property of the incident light by measuring the frequency (hertz) of the incident second light ray L2. The second measuring unit 604 can measure the incident second ray L2 while rotating the rotating quarter wave plate 603 by 360 degrees and rotate the rotating quarter wave plate 603 by 360 degrees When measuring light rays, you can analyze the light rays from all angles.

As described above, the focal length and the anisotropy of the microlens array can be simultaneously measured by using the apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention.

4 and 5, an apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention and a method for measuring characteristics of a microlens array using the apparatus will be described in detail. The description of the parts overlapping with the above-described embodiments will be omitted.

4 is a view schematically showing an apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention. FIG. 5 is a graph showing the results of an experiment for measuring a light beam incident on a second measurement unit using an apparatus for measuring a characteristic of a microlens array according to an embodiment of the present invention.

The apparatus for measuring the characteristics of a microlens array according to an embodiment of the present invention includes a light source 500, a light beam expander 505, a first light beam splitter 506, a target portion 501, a comparative lens 502, The first quarter wave plate 601, the second quarter wave plate 603, the second measurement unit 604, the half mirror 701, the reflection mirror 702, the modulator 504, (703) and a second beam splitter (704).

The first microlens array 503 as the characteristic measurement object can be positioned between the comparison lens 502 and the first measurement unit 504 and the second microlens array 602 as the characteristic measurement object can be positioned between the 1/4 wavelength And may be positioned between the plate 601 and the rotating quarter wave plate 603. [ The same microlens array may be disposed at the positions of the first microlens array 503 and the second microlens array 602.

The first beam splitter 506 splits the light beam in the same ratio and proceeds. The first light beam L1 divided at the same ratio can be refracted at 90 degrees to be incident on the target portion 501 and the first light beam L1 incident on the target portion 501 can be used as in the above- The focal length of the microlens array can be obtained.

The second light beam L2 divided by the same ratio and going straight ahead is reflected by the third light beam L3 which is transmitted through about 50% in the semi-transparent mirror 701 and goes straight, And may be divided into four rays L4. The third light beam L3 transmitted through the semi-transmission mirror 701 and traveling straight can be incident on the quarter wave plate 601 and the third light beam L3 incident on the quarter wave plate 601 The anisotropic characteristics of the microlens array can be measured as in the above-described embodiments.

The fourth light beam L4 reflected by the transflective mirror 701 and refracted by 90 degrees is reflected by the reflective mirror 702 at about 100% and enters the modulator 703. The modulator 703 can use a piezoelectric (PZT) element which is a material that generates a potential difference when a pressure is applied and a physical displacement occurs when a voltage is applied thereto. When an electric field is applied to the piezoelectric element, spatial modulation occurs, and the fourth light ray L4 transmitted through the piezoelectric element is shaken to modulate the phase of the fourth light ray L4. That is, it is possible to control the phase change of the fourth light ray L4 passing through the piezoelectric element by adjusting the electric field applied to the piezoelectric element.

The fourth light beam L4 traveling through the modulator 703 travels through the quarter wave plate 601 and the third quarter wave plate 603 and travels through the third light beam L3 and the second light beam splitter 603, (704) and is incident on the second measurement unit (604).

Hereinafter, a method of measuring refractive index, curvature and chromatic aberration of a microlens array using a microlens array characteristic measuring apparatus will be described.

First, the electric field applied to the piezoelectric element is adjusted so that the phase of the fourth light beam L4 passing through the piezoelectric element is changed by 0, and then the light beam incident on the second measurement unit 604 is measured. The phase of the fourth light beam L4 passing through the second measuring unit 604 is measured after the phase of the fourth light beam L4 is changed by? / 2, and the phase of the fourth light beam L4 passing through the piezoelectric element is measured And the light beams incident on the second measurement unit 604 when they are changed by? And 3? / 2, respectively. That is, the electric field applied to the piezoelectric element is adjusted so that the phase of the fourth light ray L4 transmitted through the piezoelectric element is changed by 0,? / 2,?, 3? / 2, A light ray incident on the light source 604 is measured.

ψ (x, y) = tan -1 [{I (x, y; 3π / 2) - I (x, y; π / 2)} / {(I (x, y; 0) -I (x, y;?)}] Equation (2)

In the equation (2), ψ (x, y) represents a phase value and I (x, y; 3π / 2) is set so that the phase of the fourth light ray L4 transmitted through the piezoelectric element is changed by 3π / 2 Is a value obtained by measuring a ray of light incident on the second measuring unit 604 and I (x, y;? / 2) is a value obtained by setting the phase of the fourth ray L4 passing through the piezoelectric element by? / 2 And is a value obtained by measuring a ray of light incident on the second measuring unit 604. Similarly, I (x, y; 0) is a value obtained by measuring a ray of light incident on the second measurement unit 604 after setting the phase of the fourth ray L4 passing through the piezoelectric element to change by 0, and I ( x, y;?) is a value obtained by measuring the ray incident on the second measuring unit 604 after setting the phase of the fourth ray L4 passing through the piezoelectric element to change by?. That is, the electric field applied to the piezoelectric element is adjusted so that the phase of the fourth light beam L4 transmitted through the piezoelectric element is changed by phi, and in each case, the light rays incident on the second measurement portion 604 are measured By substituting the value of I (x, y; φ) into the equation (2), the phase value ψ (x, y) can be obtained.

5A is a photograph showing a spatial distribution of light rays measured by the second measuring unit 604 when the voltage applied to the piezoelectric element is set to 3 V in an example, Is a photograph of the spatial distribution of the light beam measured by the second measuring unit 604 when the voltage applied to the piezoelectric element is set to 4 V as an example. 5 (A) and 5 (B), the voltage applied to the piezoelectric element is set differently so that I (x, y; phi), which is a value when the phase of the fourth light ray L4 passing through the piezoelectric element changes by phi, (X, y) can be obtained by substituting a plurality of I (x, y;?) Values into the equation (2). The graph of the phase value? (X, y) is shown in FIG. 5C. The x-axis represents the position and the y-axis represents the phase value?. The position of the graph on the x-axis in Fig. 5 (C) shows the position along the line j-j 'in Figs. 5 (A) and 5 (B), and the shape of the graph in Fig. ) And a cross-sectional shape taken along line j-j 'in Fig. 5 (B). Therefore, the height d of the graph of FIG. 5 (C) means the height d of each lens of the microlens array.

? = 2? * n * d /? (3)

In Equation (3), 隆 represents a phase value as ψ in Equation (2), d represents height (d) of each lens of the microlens array, and n represents a refractive index (n) of the microlens array denotes a wavelength (?) of a light source output from the light source unit 500, and? Therefore, the phase value? Obtained through the second measurement unit 604 at n = (? *?) / (2? * D) and the height of each lens of the microlens array obtained through the graph of FIG. (n) of the microlens array can be obtained by substituting the value (d) of the light source unit 500 and the wavelength (?) value of the light source output from the light source unit 500. [ FIG. 5D is a graph showing the refractive index n of the microlens array obtained in this manner.

Further, the curvature value (nd) of the microlens array can be obtained by multiplying the refractive index (n) of the microlens array by the height (d) of each lens of the microlens array obtained through the graph of FIG. 5 (C).

Further, when a light source having a color such as red, green, and blue is used in the light source unit 500, the refractive index n is measured for each wavelength band according to each color, and chromatic aberration caused by a difference in refractive index ) Can be measured.

Although the method of measuring the refractive index and the curvature of the microlens array has been described with reference to the embodiment, the method of measuring the refractive index and the curvature of the microlens array is not limited thereto. For example, It is also possible to set the piezoelectric element to be changed by another phase other than setting the piezoelectric element so that the phase changes by 0,? / 2,?, 3? / 2. It is also possible to measure not only the microlens array but also the properties of a film-like object.

As described above, the focal length, the anisotropy, the refractive index, the curvature, and the chromatic aberration of the microlens array can be simultaneously measured using the microlens array characteristic measuring apparatus according to an embodiment of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

500: light source 501:
502: Comparison lens 503: First microlens array
504: first measuring unit 505:
506: First light splitter 601: 1/4 wavelength cold
602: second microlens array 603: rotating quarter wave plate
604: Second measuring unit 701: Semitransparent mirror
702: Reflecting mirror 703: Modulator
704: Second beam splitter

Claims (17)

A light source for outputting a light beam parallel to the optical axis, a target portion, a comparison lens, and a first measurement portion in this order;
Outputting a light beam from a light source;
The light beam passing through the target portion and the comparison lens in order and passing through a first focal point to be incident on the first measurement portion and projecting a first image of the target portion onto the first measurement portion;
Measuring a size of the first image in the first measurement unit;
Fixing and arranging a first microlens array between the comparison lens and the first measurement unit;
Outputting the light beam again from a light source;
The light beam passes through the target portion, the comparison lens, and the first microlens array in order, passes through a second focal point, and is incident on the first measurement portion, Is projected;
Measuring a size of the second image in the first measurement unit;
Obtaining a distance traveled from the first focus to the second focus using a first focal distance of the first focus of the comparison lens, a size of the first image, and a size of the second image doing
Method of measuring microlens array characteristics. The method of claim 1,
Wherein the step of obtaining a distance (? 1) from the first focus to the second focus includes:
Wherein the first focal length (FLr), the first image size (Ir), and the second image size (Ip)
FLr:? 1 = Ir: Ip (1)
(1). ≪ / RTI > The method of claim 1,
Positioning the first beam splitter between the light source and the target portion such that the beam splits into a first beam and a second beam traveling in different directions and the first beam is incident on the target portion;
Arranging a quarter wave plate for retarding the phase difference of the second light beam by? / 2 in the path of the second light beam;
Disposing a second microlens array on which the second light beam having passed through the 1/4 wave plate is incident;
Disposing a rotating quarter wave plate on which the second light beam having passed through the second microlens array is incident;
Disposing a second measuring unit for measuring the second light beam incident through the rotating quarter wave plate and
And measuring anisotropy by comparing the value measured by the second measuring unit with the second light ray before passing through the 1/4 wavelength plate. 4. The method of claim 3,
And when the second light beam is measured by the second measuring unit, the rotating quarter wave plate measures while rotating 360 degrees. 4. The method of claim 3,
The first light beam splitting unit splits the second light beam into a third light beam and a fourth light beam reflected by the first light beam splitter, Disposing a transmission mirror;
Disposing a modulator such that the fourth light beam reflected from the transflective mirror is incident;
Disposing a second light beam splitter to combine the third light beam and the fourth light beam into the second measurement unit;
Changing the phase of the fourth light beam by applying an electric field to the modulator; And
And measuring a light beam incident on the second measurement unit. The method of claim 5,
Changing the phase of the fourth light beam by applying an electric field to the modulator, and measuring the light beam incident on the second measurement unit,
Wherein the refractive index of the second microlens array is measured repeatedly a plurality of times while changing the electric field applied to the modulator. The method of claim 6,
Wherein the modulator comprises a piezoelectric element. The method of claim 6,
And changing the hue of the light source to measure the refractive index of the second microlens array for each hue. The method of claim 6,
Wherein the step of measuring the refractive index of the second microlens array comprises:
(X, y,? 1), I (x, y) measured by the second measuring unit while changing the phase of the fourth light beam by changing the electric field applied to the modulator to? 1,? 2,? 3, (x, y;? 3) and I (x, y;? 4)
ψ (x, y) = tan -1 [{I (x, y; φ1) - I (x, y; φ2)} / {(I (x, y; φ3) -I (x, y; φ4) }] (2)
(2) to obtain a phase value (?),
The height (d) of each lens of the second microlens array is obtained by expressing the phase value (?) In a graph,
? = 2? * n * d /? (3)
(D) of each lens of the second microlens array is substituted for d in the equation (3), and the wavelength (?) Of the second light beam is assigned to? To obtain a refractive index (n). The method of claim 9,
Wherein the refractive index (n) is multiplied by a height (d) of each lens of the second microlens array to obtain a curvature of the second microlens array. 11. The method of claim 10,
Wherein the second measuring unit is a CCD (Charge-Coupled Device) camera or a photodiode or an oscilloscope. A light source for outputting a light beam parallel to the optical axis;
A target portion on which the light beam is incident;
A comparative lens through which the light beam having passed through the target portion is incident;
A first microlens array through which the light beam having passed through the comparison lens is incident; And
And a first measurement unit for measuring the light beam that has passed through the first microlens array,
Wherein the comparison lens and the first measuring unit are fixed,
The first microlens array does not move while measuring the focal length of the first microlens array,
The first measuring unit measures the size of the projected image of the target portion
Microlens array characteristic measuring device. The method of claim 12,
A first light beam splitter positioned between the light source and the target portion and dividing the light beam into a first light beam and a second light beam traveling in different directions;
A quarter wave plate located in a path along which the second light ray travels and delaying the phase difference of the second light ray by? / 2;
A second microlens array through which the second light beam having passed through the 1/4 wave plate is incident; And
And a rotating quarter wave plate through which the second light beam having passed through the second microlens array is incident,
Wherein the target portion, the comparison lens, and the first measurement portion are located on a path along which the first light beam travels
Microlens array characteristic measuring device. The method of claim 13,
Wherein the rotating quarter wave plate rotates 360 degrees while measuring anisotropy of the second microlens array. The method of claim 13,
A transflective mirror positioned between the first light beam splitter and the quarter wave plate and dividing the second light beam into a third light beam and a fourth reflected light beam; And
And a modulator
Further comprising:
Wherein the quarter wave plate and the rotating quarter wave plate are disposed in a path along which the third light ray travels
Microlens array characteristic measuring device. 16. The method of claim 15,
Wherein the modulator includes a piezoelectric element that can change a phase of a transmitted light by adjusting an applied electric field. 17. The method of claim 16,
A second light splitter for combining the third light beam and the fourth light beam; And
And a second measurement unit for receiving the combined light beams from the second light beam splitter,
Further comprising a micro lens array.

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