A method and simple detection device for detecting phase difference of optical components

Abstract

The invention discloses a detection method and a simple detection device for the phase difference of an optical component. A combination scheme of a laser light source, a polarizer, an analyzer and an optical power detector is adopted to replace the components of a polarization measuring instrument. A specific fitting method is adopted to realize the phase difference detection of an optical component to be detected. Meanwhile, a second adjustment frame on which the optical component to be detected is placed is arranged to be rotatable around a central axis perpendicular to a horizontal plane, and a third adjustment frame on which the analyzer is placed and an optical power detector are fixedly arranged on a rotating arm rotatable around the central axis of the second adjustment frame. Thus, the detection requirements of the transmission and reflection phase differences can be realized on one device at the same time. The total cost of the whole set of equipment is less than RMB 10,000, which greatly reduces the equipment cost. The equipment has basically the same accuracy as that of existing detection equipment and can fully meet the needs of phase difference detection.

Description

Technical Field

[0001] The present invention relates to detection of phase difference of an optical component, and in particular to a detection method and a simple detection device for phase difference of an optical component. Background Art

[0002] The existing methods for detecting optical phase difference mainly use a polarization meter to collect the Stokes parameters of the outgoing light, and then use a formula to calculate the phase difference data.

[0003] The Chinese invention patent disclosure with publication number CN 117147105A discloses a system and method for measuring the phase difference of optical thin films, which uses a combination of a multi-wavelength laser light source, a polarizer, a carrier and a polarization meter to collect the Stokes parameters of the emitted light and then use a formula to calculate the transmission phase difference. However, the polarization meter used in this solution is relatively expensive, costing about RMB 50,000, and there is no detection solution for the reflection phase difference. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method and a simple detection device for detecting the phase difference of an optical component with relatively low equipment cost and capable of measuring the transmission and reflection phase differences.

[0005] The technical solution adopted by the present invention to solve the above technical problem is: a method for detecting the phase difference of an optical component, comprising the following steps:

[0006] Step 1: The detection light passes through the polarizer, the optical component to be detected and the analyzer in sequence and enters the optical power detector;

[0007] Step 2: Adjust the polarizer to obtain linearly polarized light with an angle of 45° between the polarization direction and the horizontal plane and a phase difference of 0°;

[0008] Step 3: After the linearly polarized light obtained in step 2 is reflected or transmitted through the optical component to be detected, an elliptically polarized light with a phase difference of φ is obtained;

[0009] Step 4: Adjust the polarizer and observe the reading of the optical power detector to obtain the ratio of the maximum and minimum light intensity. P And the angle between the polarization direction of the light passing through the analyzer and the horizontal plane when the light intensity is at its maximum θ ;

[0010] Step 5: In the plane rectangular coordinate system ( x , y ) characterizes the projection trajectory of the elliptically polarized light in a plane perpendicular to its propagation direction, where x is the coordinate value of the X-axis in the plane rectangular coordinate system, denoted as x=Asin(π / 180*t), y is the coordinate value of the Y axis in the plane rectangular coordinate system, denoted as y =Bsin(π / 180*t+φ), A and B are the amplitudes of the elliptically polarized light decomposition on the X-axis and Y-axis respectively, tan θ =B / A, t is a specific time point in a cycle, the value range is 0≤t≤360, φ is the phase difference, the value range is 0≤φ≤360;

[0011] Step 6: Select a φ value and then increase t from 0 in steps of n Step by step, gradually increase to 360, and get N =360 / n The coordinate values ​​of the points are connected in sequence to obtain an ellipse. The length of the major axis and the length of the minor axis of the ellipse are recorded, and the ratio of the major axis to the minor axis is recorded as Q ;

[0012] Step 7: Set φ starting from 0 and stepping m Step by step, gradually increase to 360, repeat step 6 once for each step, and get M =360 / m Ratio of the major axis length to the minor axis length Q M ;

[0013] Step 8: Find the P The closest Q M , the Q M The value of φ corresponding to the value of is taken as the phase difference of the elliptically polarized light.

[0014] Compared with the prior art, the advantage of the present invention is that the present invention addresses the disadvantage of expensive equipment in existing phase difference detection solutions, and by collecting the power parameters and angle of the output polarized light and using a calculation fitting method, the phase difference can be calculated without collecting Stokes parameters.

[0015] Preferably, the step length of t n= 0.1, the step size of φ m= 0.1. The stride of t and the stride of φ are both 0.1 to strike a balance between accuracy and data volume.

[0016] The present invention also provides a simple detection device for realizing the above detection method, comprising a working platform, on which a laser light source for emitting detection light, a first adjustment frame for setting a polarizer, a second adjustment frame for setting an optical component to be detected, a third adjustment frame for setting an analyzer and an optical power detector for detecting optical power are arranged. The first adjustment frame can make the polarizer rotate around the optical axis in a plane perpendicular to the horizontal plane, the second adjustment frame can make the optical component to be detected rotate around the central axis perpendicular to the horizontal plane, the third adjustment frame can make the analyzer rotate around the optical axis in a plane perpendicular to the horizontal plane, and the working platform is also provided with a rotating arm coaxial with the second adjustment frame, the rotating arm can rotate around the central axis of the second adjustment frame, and the third adjustment frame and the optical power detector are fixedly arranged on the rotating arm. The present invention adopts a combination of a laser light source, a polarizer, an analyzer and an optical power detector to replace the components of a polarization measuring instrument, and adopts a specific fitting method to realize phase difference detection of optical components. At the same time, by setting the second adjustment frame for placing the optical components to be detected to be able to rotate around the central axis perpendicular to the horizontal plane, and fixing the third adjustment frame for placing the analyzer and the optical power detector on a rotating arm that can rotate around the central axis of the second adjustment frame, the transmission and reflection phase difference detection requirements can be realized on one device at the same time, and the total cost of the whole set of equipment is less than 10,000 yuan, which greatly reduces the equipment cost. By comparison, the accuracy is basically the same as that of the existing detection equipment, which can fully meet the needs of phase difference detection.

[0017] Preferably, the working platform is provided with a circular or semicircular guide rail with the central axis of the second adjustment frame as the center, and the rotating arm is slidably matched with the guide rail. This structure can ensure the stability of the rotating arm when rotating and improve the accuracy of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a simple detection device according to an embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the decomposition of elliptically polarized light in a plane rectangular coordinate system in the method of the present invention.

[0020] Description of reference numerals:

[0021] 800, working platform; 100, laser light source; 201, polarizer; 202, analyzer; 301, first adjustment frame; 302, second adjustment frame; 303, third adjustment frame; 400, optical power detector; 500, guide rail; 600, rotating arm; 700, optical components to be detected. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings.

[0023] Embodiment 1: Figure 1The figure shows a simple detection device for the phase difference of an optical component of the present invention, which includes a working platform 800, on which are arranged a laser light source 100, a polarizer 201 and an analyzer 202, a first adjustment frame 301, a second adjustment frame 302 and a third adjustment frame 303, an optical power detector 400, a semicircular guide rail 500, a rotating arm 600 and an optical component 700 to be detected. The laser light source 100 is used to emit detection light along a preset optical path, and a laser of corresponding wavelength can be selected according to different required wavelength bands. The polarizer 201 and the analyzer 202 select the simplest polarizer. The polarizer 201 is attached to the first adjustment frame 301 with an angle scale. The first adjustment frame 301 can drive the polarizer 201 to rotate together in a plane perpendicular to the horizontal plane, so as to calibrate the polarization direction of the detection light. The analyzer 202 is attached to a third adjustment frame 303 with an angle scale, and the third adjustment frame 303 can drive the analyzer 202 to rotate in a plane perpendicular to the horizontal plane. The second adjustment frame 302 with an angle scale can clamp the optical component 700 to be detected, and can rotate in the horizontal plane to make the optical component 700 to be detected rotate around the central axis perpendicular to the horizontal plane, so as to adjust the angle between the optical component 700 to be detected and the detection light. The optical power detector 400 is used to collect the light intensity information of the detection light. A commonly used optical power meter is used here, which is set on the rotating arm 600 together with the third adjustment frame 303. One end of the rotating arm 600 is coaxially arranged with the second adjustment frame 302, so that the rotating arm 600 can rotate around the central axis of the second adjustment frame 302, so as to receive the detection light of different angles emitted from the optical component 700 to be detected. The other end of the rotating arm 600 is slidably matched with the semicircular guide rail 500. The guide rail 500 takes the central axis of the second adjustment frame 302 as the center, and the rotating arm 600 carrying the optical power detector 400 and the third adjustment frame 303 can slide on the guide rail 500. The working platform 800 can be moved as a whole for easy transportation. When detecting the phase difference of transmitted light, the laser light source 100, the polarizer 201, the optical component to be detected 700, the analyzer 202 and the optical power detector 400 are arranged in a straight line. At this time, the incident angle of the detection light emitted by the laser light source 100 on the surface of the optical component to be detected 700 is 0; when detecting the phase difference of reflected light, the second adjustment frame 302 is rotated to make the incident angle of the detection light emitted by the laser light source 100 on the surface of the optical component to be detected 700 is a certain angle, and then the rotating arm 600 is rotated to make the light emitted by the optical component to be detected 700 vertically incident on the surface of the analyzer 202; whether it is transmission or reflection, the simple detection device of the present invention can make the detection light emitted by the laser light source 100 pass through the polarizer 201, the optical component to be detected 700 and the analyzer 202 in sequence, and be received by the optical power detector 400.

[0024] In this embodiment, by adjusting the polarizer 201 so that the angle between the polarization direction of the polarized light and the horizontal plane is 45°, and the phase difference φ is 0°, after being reflected or transmitted by the optical component 700 to be detected, the phase difference φ changes to form elliptically polarized light, and by adjusting the analyzer 202 and observing the reading of the optical power detector 400, the ratio of the maximum and minimum light intensity of the detection light is found and recorded. P and the angle between the polarization direction of the polarized light of the analyzer 202 and the horizontal plane when the light intensity is at the maximum value θ .

[0025] like Figure 2 As shown, by decomposing the light, it can be expressed in the plane rectangular coordinate system as ( x , y ) represents the projection trajectory of elliptically polarized light in a plane perpendicular to its propagation direction, where x is the coordinate value of the X-axis in the plane rectangular coordinate system, denoted as x =Asin(π / 180*t), y is the coordinate value of the Y axis in the plane rectangular coordinate system, denoted as y =Bsin(π / 180*t+φ), A and B are the amplitudes of elliptically polarized light decomposition on the X-axis and Y-axis, tan θ = B / A, t is a specific time point in a cycle, the value range is 0≤t≤360, φ is the phase difference, the value range is 0≤φ≤360; in this embodiment, a computer is used to step φ from 0 m= 0.1 step, gradually increase to 360, each time a φ value is selected, repeat the following steps: start t from 0 and increase it by 0.1 step. n= 0.1 step, gradually increase to 360, and get N =360 / n The coordinate values ​​of the points are connected in sequence to form an ellipse. The length of the major axis and the length of the minor axis of the ellipse are recorded to obtain the ratio of the major axis to the minor axis. Q Finally, we get M =360 / m Ratio of the major axis length to the minor axis length Q M ; Use computer search to find P The closest Q M , the Q M The value of φ corresponding to the value of is taken as the phase difference of the elliptically polarized light.

[0026] At a wavelength of 905 nm, the simple detection device and detection method of the present invention and the detection method of the existing equipment using a polarization measuring instrument are used to detect the same sample at a phase difference of 0° and 60° at the incident angle of the detection light. The results are shown in Table 1:

[0027] Table 1

[0028] Test items The present invention (°) Existing technology (°) 0° incident angle transmission phase difference 0.1 0.1 60° incident angle transmission phase difference 2.2 2.3

Claims

1. A method for detecting phase difference of an optical component, characterized in that: The following steps are involved: Step 1: The detection light passes through the polarizer, the optical component to be detected and the analyzer in sequence and enters the optical power detector; Step 2: Adjust the polarizer to obtain linearly polarized light with an angle of 45° between the polarization direction and the horizontal plane and a phase difference of 0°; Step 3: After the linearly polarized light obtained in step 2 is reflected or transmitted through the optical component to be detected, an elliptically polarized light with a phase difference of φ is obtained; Step 4: Adjust the polarizer and observe the reading of the optical power detector to obtain the ratio of the maximum and minimum light intensity. P And the angle between the polarization direction of the light passing through the analyzer and the horizontal plane when the light intensity is at its maximum θ ; Step 5: In the plane rectangular coordinate system ( x , y ) characterizes the projection trajectory of the elliptically polarized light in a plane perpendicular to its propagation direction, where x is the coordinate value of the X-axis in the plane rectangular coordinate system, denoted as x =Asin(π / 180*t), y is the coordinate value of the Y axis in the plane rectangular coordinate system, denoted as y =Bsin(π / 180*t+φ), A and B are the amplitudes of the elliptically polarized light decomposition on the X-axis and Y-axis respectively, tan θ =B / A, t is a specific time point in a cycle, the value range is 0≤t≤360, φ is the phase difference, the value range is 0≤φ≤360; Step 6: Select a φ value and then increase t from 0 in steps of n Step by step, gradually increase to 360, and get N =360 / n The coordinate values ​​of the points are connected in sequence to obtain an ellipse. The length of the major axis and the length of the minor axis of the ellipse are recorded, and the ratio of the major axis to the minor axis is recorded as Q ; Step 7: Set φ starting from 0 and stepping m Step by step, gradually increase to 360, repeat step 6 once for each step, and get M =360 / m Ratio of the major axis length to the minor axis length Q M ; Step 8: Find the P The closest Q M , the Q M The value of φ corresponding to the value of is taken as the phase difference of the elliptically polarized light.

2. A method for detecting phase difference of an optical component as claimed in claim 1, characterized in that: The stride of t n= 0.1, the step size of φ m= 0.

1.

3. A simple detection device for implementing the detection method of claim 1, comprising a working platform, wherein the working platform is provided with a laser light source for emitting detection light, a first adjustment frame for setting a polarizer, a second adjustment frame for setting an optical component to be detected, a third adjustment frame for setting an analyzer, and an optical power detector for detecting optical power, wherein: The first adjustment frame can make the polarizer rotate around the optical axis in a plane perpendicular to the horizontal plane, the second adjustment frame can make the optical component to be detected rotate around the central axis perpendicular to the horizontal plane, and the third adjustment frame can make the analyzer rotate around the optical axis in a plane perpendicular to the horizontal plane. The working platform is also provided with a rotating arm coaxial with the second adjustment frame, and the rotating arm can rotate around the central axis of the second adjustment frame. The third adjustment frame and the optical power detector are fixedly arranged on the rotating arm.

4. The simple detection device according to claim 3, characterized in that: The working platform is provided with a circular or semicircular guide rail with the central axis of the second adjustment frame as the center, and the rotating arm is slidably matched with the guide rail.

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