KR200355431Y1 - Prism coupler - Google Patents

Abstract

The present invention is a device for measuring the refractive index, thickness and light propagation loss of an optical thin film. In the case of a dielectric thin film having a thickness of 1 to 30 μm, the thickness, refractive index, and propagation loss can be precisely measured at the same time, and the thickness is 1 to 150. Thick thick films up to [mu] m and general bulk materials or liquid materials relate to prism couplers capable of measuring the refractive index as well as the angle of the optical component.

According to the present invention, a signal light source input unit 100 for inputting while rotating a signal light and a prism and a loss measuring support 300 for incident the signal light of the signal light source input unit 100 through a prism and measuring the reflected output light 300 And an angle measuring unit 200 for distributing the signal light of the signal light source input unit 100 through the optical splitter 140 to measure the thickness of the thick object (thick film), and the angle measuring unit 200 ) Is an angle measuring table 220, a thin film, a thick film, a bulk film or an optical component for measuring an angle, and a height adjusting lever 230 for adjusting the height of the angle measuring table 220. The angle measuring light receiving unit 210 detects the reflected light reflected on the object to be measured.

Description

Prism Coupler {PRISM COUPLER}

The present invention relates to a prism coupler, and more particularly, a device for measuring the refractive index, thickness, and light propagation loss of an optical thin film. In the case of a dielectric thin film having a thickness of 1 to 30 μm, the thickness, refractive index, and propagation loss are precisely simultaneously. In the case of a thick thick film having a thickness of 1 to 150 µm and a general bulk material or a liquid material, it is possible to measure a refractive index as well as a prism coupler capable of measuring an angle of an optical component.

The prism coupler is a device for non-destructively measuring the refractive index and thickness of a thin film when an organic material or an inorganic material is manufactured in the form of a thin film. After passing through the slope of the prism while reaching the angle of incidence of the signal light using the laser beam, the bottom of the prism is reached. At this time, the total reflection is performed at the bottom to detect light totally reflected by a detector located opposite the prism. However, at a specific angle of incidence, light is not totally reflected at the bottom of the prism, but rather light is directed to the object under test (usually a thin film). When a phenomenon of coupling of light into a thin film, which is a measurement target, occurs, the intensity of the light reaching the detector due to the leakage of light rapidly decreases. This is caused by the coupling of light from the prism into the thin film. The light entering at a certain angle of incidence satisfies the waveguide conditions of the light in the thin film, thereby significantly reducing the intensity of light detected by the photodetector. Since the coupling phenomenon of light is satisfied at several specific angles of incidence, there are several minimum points where the intensity of light is significantly reduced. After obtaining several values where the intensity of light is the minimum point, substitute them into a formula that satisfies the waveguide condition and calculate the refractive index and thickness by numerical method.

Korean Registered Patent No. 0352585 (Invention name: Prism coupler device and control method) relates to a prism coupler, in particular, by using a linear translator (Linear Translator) to accurately place the prism and the laser to be measured, An apparatus and method are disclosed that can accurately measure the refractive index and thickness of water.

In the case of measuring the refractive index using the conventional prism coupler as described above, after the measurement object is attached to the prism, if the light is not coupled to the object under the prism, the total reflection is detected to maximize the light intensity while the light is When the light leaks from the detector when it is coupled to the object under test, it uses the principle. Therefore, it is important to determine the angle of incidence in which the intensity of light falls rapidly, but it is difficult to clearly set the reference point for setting the incident light.

On the other hand, the conventional prism coupler has no function of measuring the prism angle, and the function of measuring the thickness of the thick film, which is a thick thin film, is complicated. In other words, the conventional prism coupler has the trouble of removing the prism from the prism coupler to measure the thickness of the thick film, and attaching the thick film to be measured to the air intake using the air inhaler. It should be exactly coincident with the surface of, but if the support of the thin film with the air intake is very difficult to set the reference point.

The present invention is to solve the above problems, the object of the present invention is to clearly determine the incident point of the laser beam, to eliminate the hassle of removing the existing optical components and attaching a new device in measuring the thick thin film thickness The refractive index of the bulk material is obtained using the Brewster's angle of TM mode, and a beam splitter is placed on the optical path of the signal light (incident light) in order to measure the angle of the edge of the optical component. It provides a prism coupler that can measure the thickness and refractive index of a thin film with light, and the thickness of a thick film with a thick thickness with the other distributed light, the refractive index of a bulk material, and the angle of a corner of an optical component. It is.

1 is a schematic configuration diagram of a prism coupler according to an embodiment of the present invention;

2 is an explanatory diagram for explaining an optical path of a signal light in a prism coupler according to an embodiment of the present invention;

3 is an explanatory view for measuring the thickness of the thin film and the thick film of the prism coupler according to the present invention and the angle measurement of the corners of the optical component;

Figure 4 is an explanatory diagram for measuring the refractive index and the thickness of the thin film of the prism coupler according to the present invention.

<Description of Symbols for Main Parts of Drawings>

100: signal light source input unit 110: rotation guide

120: light source 130: primary reflection part

140: light splitter 145: zero light receiving unit

150: secondary reflection unit 160: rotary stage

200: angle measuring unit 210: angle measuring light receiving unit

220: angle measuring table 230: height adjustment lever

300: prism and loss measuring support 310: index of refraction and thickness

320: reflected light receiver 325: radio wave loss measurement receiver

330: piston 340: prism

345: measured object

According to the present invention, a signal input (incident light) having a constant wavelength is incident on an object to be measured, and a signal input while rotating the signal light as a prism coupler which measures the output light reflected from the bottom of the prism and calculates and measures the refractive index and thickness by a computer. A light source input unit 100, a prism and a loss measuring support 300 for incident the signal light of the signal light source input unit 100 through a prism and measuring the reflected output light, and the signal light source input unit 100. It is characterized in that it comprises an angle measuring unit 200 for measuring the thickness of the thick to-be-measured object (thick film) by distributing the signal light through the optical splitter 140.

In addition, the angle measuring unit 220 is preferably placed on the rotation axis of the signal light source input unit 100, the thin film, thick film, bulk film and the optical component to measure the angle on the angle measuring unit 200 and A height adjusting lever 230 for adjusting the height of the angle measuring table 220 and an angle measuring light receiving unit 210 for detecting reflected light reflected from the object to be measured of the angle measuring table 220 are included. It features.

The present invention is a prism coupler for measuring the refractive index and the thickness of a thin film by detecting the reflected light reflected by the incident light to the target object to reflect the signal light of a constant wavelength, by setting the reference point of the incident light precisely by placing an optical splitter on the path of the signal light At the same time, it is equipped with an angle measuring unit that measures the thickness of the thick film, the refractive index of the bulk film, and the angle of the optical part, and the refractive index and thickness of the thin film, the thickness of the thick film, the refractive index of the bulk material, and the angle of the optical part without the inconvenience of changing a new part. It features a prism coupler that can measure bays.

Hereinafter, with reference to the accompanying drawings will be described in detail the prism coupler of the present invention. In adding reference numerals to the components of each drawing, the same components, even if displayed on the other drawings to have the same reference numerals as possible, it is known that it may unnecessarily obscure the subject matter of the present invention Detailed description of functions and configurations will be omitted.

1 is a schematic configuration diagram of a prism coupler according to an embodiment of the present invention, Figure 2 is an explanatory diagram for explaining the optical path of the signal light in the prism coupler according to an embodiment of the present invention, Figure 3 It is an explanatory view for measuring the thickness of the thin film and thick film of the prism coupler and the angle measurement of the edge portion of the optical component according to the present invention, Figure 4 is an explanatory diagram for measuring the refractive index and the thickness of the thin film of the prism coupler according to the present invention.

Prism coupler according to a preferred embodiment of the present invention is a signal light source input unit 100 for inputting while rotating a signal light having a predetermined wavelength, in a frame 50 of a predetermined size, as shown in Figure 1 to 4, The prism and loss measuring support 300, which inputs the signal light of the signal light source input unit 100 through a prism and measures the reflected output light, and the signal light of the signal light source input unit 100 through an optical splitter. It is configured to include an angle measuring unit 200 to measure the thickness of the thick thin film, the refractive index of the bulk material and the angle of the optical component by dispensing. In this case, the type of the signal light of the signal light source input unit 100 may be selectively selected, and numerical analysis of the refractive index and thickness of the thin film may be performed by the detection signals through the prism and the loss measuring support 300 and the angle measuring unit 200. Is done through a computer not shown.

The signal light source input unit 100 is connected to one side of the rotary stage 160 and the rotary stage 160 fixed to the frame 50, and the prism and loss measuring support 300 and the angle measuring unit 200. ) And outputs a constant signal light and rotates at a constant speed under the control of the rotary stage 160. In addition, the rotation guide 110 includes a plurality of light sources 120 for outputting the signal light, a first reflection unit 130 for total reflection of the signal light of the light source 120, and the first reflection unit 130. A beam splitter 140 for outputting part of the signal light to the angle measuring part 200 and distributing part of the signal light to the angle measuring part 200 and a signal light through the light splitter 140 to the prism and loss measuring support 300. It is configured to include a second reflecting unit 150 for total reflection to be output. In addition, one side of the optical splitter 140 is configured to further include a zero point receiving unit 145 for detecting the signal light reflected through the second reflecting unit 150. The signal light source input unit 100 is controlled by an external computer, and the light source 120 may use various light sources such as wavelengths of 635 nm, 1310 nm, and 1350 nm.

The angle measuring unit 200 is an angle measuring table 220 on which a thin film, a thick film, a bulk film or an optical component for measuring an angle is placed, and a height for adjusting the height of the angle measuring table 220. The adjustment lever 230 and the angle measuring light receiving unit 210 for detecting the reflected light reflected on the object to be measured of the angle measuring table 220 is configured.

The object to be measured is called a thin film having a thickness of 0.1 μm to 30 μm, and a thick film having a thickness of about 150 μm from the region of the thin film is called a thick film. The object to be placed on the angle measuring table 220 first adjusts the height adjusting lever 230 to coincide with the rotation axis of the rotary stage 160 as shown in FIG. 2. Then, when coinciding with the rotation axis, the rotary stage 160 is rotated to output the signal light from the light source 120, the output signal light is incident on the object to be measured through the optical splitter 140. The incident signal light is reflected to measure the intensity of the light by the angle measuring light receiving unit 210. In this case, the thickness is measured by measuring the thickness of the thick film, which is a thick thin film, from the maximum and minimum positions of the interference fringe generated while varying the angle of the monochromatic light incident on the thin film by the Variable Angle Monochromatic Fringe Observation (VAMFO) method. On the other hand, when the bulk film is placed thereon, the reflectance is measured to the minimum at a specific rotation angle of the TM mode, which is called a brewster angle, and the refractive index of the bulk film is determined from the Brewster angle. When the optical component to be measured at the same position is placed, the light is incident on two sides of the corner perpendicularly, and about 4% is reflected. When the reflected light is measured on the two sides, the angle of the corner can be measured.

The prism and loss measuring support 300 includes a refractive index and a thickness measuring table 310 mounted to closely adhere to the prism to be measured, a reflected light receiving unit 320 for detecting reflected light reflected by the prism, and the measured object And a piston 330 for closely contacting the object to be measured at a predetermined pressure with the radio wave loss measurement light receiver 325 for detecting the reflected light reflected through the water. Since the piston 330 pushes the object 345 to the prism 340 at a constant pressure as shown in FIG. 2, the piston 330 may be in close contact with the prism 340 regardless of the object 345.

Referring to the operation effect of the present invention configured as described above, first to measure the thickness and refractive index of the object to be measured, the prism 340 by operating the piston 330 to the object 345 to the prism and loss measuring support 300 ) So that it is in close contact with In this case, the reference point is first determined such that an incident angle incident on the prism 340 is 0 degrees. In general, about 4% of incident light is reflected when the reference point is perpendicular to the prism 340. The reflected reflected light is irradiated to the optical splitter 140 through the secondary reflector 150, and the reflected reflected light is detected through the zero light receiver 145 to set an accurate reference point 14.

Thereafter, when the incident light 16 is incident on the reference point 14 while changing the incident light 16 in accordance with the incident angle θ _i , the reflected light receiving part outside the prism 340 according to the refractive index np of the prism ( The light totally reflected from the bottom of the prism 340 is detected through 320.

When the propagation constant k _Z of the laser beam in the Z axis (thin film to horizontal axis) direction of the prism 340 is equal to the high propagation constant of the thin film 12, the intensity of light detected by the reflected light receiving unit 320 is extremely small. As a result, a peak is achieved.

k _Z = k _O n _P sin [θ _P -sin ^-1 (sin (θ _i / n _P ))]

Where k _O is the wavelength of the light source, n _P is the refractive index of the prism, θ _P is the angle of the prism, and θ _i is the angle of incidence 16.

In other words, it is based on the principle that the light wave transition of the signal light occurs from the prism 340 to the thin film 12. At this time, the refractive index of the prism must be larger than the refractive index of the thin film in order for the light to be transferred to the thin film 12. This is a known result due to electromagnetic boundary conditions, so detailed description thereof is omitted.

As described above, at least two minimum peak points may be obtained through the measured values, and the refractive index n and the thickness T of the thin film may be obtained through Equation 1 using a value corresponding to the peak points.

On the other hand, in the case of measuring the thickness of the thin film, thick film or bulk film, the measurement object is placed on the angle measuring table 220 and the signal light is incident through the optical splitter 140. That is,, the thin film 12 to the reference point 14. When the incident according to the angle of incidence (θ _i) the incident light (16) based on the reflected light (18, which is reflected in the thin film 12 to a thickness of T, as shown in Fig. 3 ) Is detected by the angle measuring light receiving unit 210. This is measured by numerical analysis of the thickness of the thin film using the extinction and constructive interference conditions between the light reflected from the upper layer and the light reflected from the lower layer. On the other hand, when the bulk film is placed therein, the reflectance is measured at the minimum rotation angle of the TM mode, which is called the Brewster angle, and the refractive index of the bulk film is determined from the Brewster angle. If the optical component to measure the angle of the corner is placed at the same position, when light is incident vertically on two sides of the edge, about 4% is reflected. When the reflected light is measured on the two sides, the angle of the edge can be measured.

As described above, according to the present invention, by inserting the first optical splitter on the path of the signal light, it is possible to determine the exact position of the incidence point, and in the second thick film, to increase the precision and the convenience of the method, and to seek the convenience of the third bulk. The refractive index of the film can be measured using Brewster's angle, the angle of the optical part can be measured to the limit of the resolution of the rotary stage, and the fourth part does not need to be grounded to increase the mechanical safety as a measuring machine. Can be.

Claims (1)

A prism coupler in which a signal light having a constant wavelength is incident on an object to be measured and the output light reflected from the bottom of the prism is measured to calculate and measure the refractive index and thickness by a computer. A signal light source input unit 100 for inputting while rotating the signal light, a prism and a loss measuring support 300 for incident the signal light of the signal light source input unit 100 to the object to be measured through a prism and measuring the reflected output light; And an angle measuring unit 200 for measuring the thickness of the thick object to be measured (thick film) by distributing the signal light of the signal light source input unit 100 through the optical splitter 140. The angle measuring unit 200 is an angle measuring table 220 on which a thin film, a thick film, a bulk film or an optical component for measuring an angle is placed, and a height for adjusting the height of the angle measuring table 220. A prism coupler comprising an adjustment lever 230 and an angle measuring light receiving unit 210 for detecting the reflected light reflected by the object to be measured of the angle measuring table 220.