阅读说明：本技术 测量装置和测量方法 (Measuring device and measuring method ) 是由 储祥勇 宋瑛林 杨勇 于 2021-07-23 设计创作，主要内容包括：本发明公开了一种基于4f相位相干成像系统的非线性光学参数的测量装置,包括激光束调制系统,测量系统和分光镜,激光束调制系统与测量系统构成4f相位相干成像系统,测量装置还包括显微成像系统。激光束经所述分光镜后分别进入测量系统和显微成像系统,所述分光镜为透射-反射镜。通过设置显微成像系统观察待测样品,扩展了待测样品的尺寸范围。本发明还公开了一种测量方法。(The invention discloses a measuring device of nonlinear optical parameters based on a 4f phase coherent imaging system, which comprises a laser beam modulation system, a measuring system and a spectroscope, wherein the laser beam modulation system and the measuring system form the 4f phase coherent imaging system, and the measuring device also comprises a microscopic imaging system. And the laser beams respectively enter the measuring system and the microscopic imaging system after passing through the spectroscope, wherein the spectroscope is a transmission-reflection mirror. The sample to be detected is observed by arranging the microscopic imaging system, so that the size range of the sample to be detected is expanded. The invention also discloses a measuring method.)

1. A measuring device of nonlinear optical parameters based on a 4f phase coherent imaging system comprises a laser beam modulation system, a measuring system and a spectroscope, wherein the laser beam modulation system and the measuring system form the 4f phase coherent imaging system.

2. The apparatus of claim 1, wherein the beam splitter is located after a fourier plane of the 4f phase coherent imaging system.

3. The apparatus for measuring nonlinear optical parameters based on a 4f phase coherent imaging system of claim 1, wherein the microscopic imaging system comprises a microscopic imaging lens group and an imaging element.

4. The apparatus for measuring nonlinear optical parameters of 4 f-phase coherent imaging system according to claim 3, wherein said microscopic imaging lens group is a microscopic imaging lens group with adjustable imaging scale, said microscopic imaging lens group comprises at least 2 lenses.

5. The apparatus for measuring nonlinear optical parameters based on 4f phase coherent imaging system according to claim 1, characterized in that the part before the Fourier plane of the 4f phase coherent imaging system is a laser beam modulation system, comprising at least a phase stop and a first convex lens.

6. The apparatus of claim 5, wherein the distance from the phase stop to the first convex lens is equal to the focal length of the first convex lens.

7. The apparatus of claim 1, wherein the measurement system comprises at least a second convex lens and a data recording element, and the distance from the data recording element to the second convex lens is equal to the focal length of the second convex lens.

8. The apparatus for measuring nonlinear optical parameters based on 4f phase coherent imaging system according to claim 1, wherein a reflective mirror is further disposed between the laser beam modulation system and the beam splitter.

9. The apparatus for measuring nonlinear optical parameters based on 4f phase coherent imaging system according to claim 1, wherein the fourier plane position of the 4f phase coherent imaging system is the stage.

10. The apparatus of claim 7, further comprising an auxiliary focusing system, wherein the auxiliary focusing system comprises an illumination source, an aperture and a transreflector, the transreflector is disposed between the data recording element and the second convex lens, and the aperture is imaged on the Fourier plane of the 4f phase coherent imaging system via the transreflector and the second convex lens.

11. The apparatus according to claim 3 or 7, wherein the imaging element and/or the data recording element is one of a CCD, a LCoS, or a DMD.

12. The nonlinear optical parameter measurement device based on the 4f phase coherent imaging system according to claim 9, wherein the stage is a three-dimensional adjustable support, the adjustment precision is 0.1 micrometer, the adjustment range is 0-20 mm, preferably, the stage adjustment precision is 10nm, and the adjustment range is 0-2 mm.

13. A method for measuring nonlinear optical parameters based on a 4f phase coherent imaging system, using the measuring apparatus according to any one of claims 1-12, the method comprising:

step a), obtaining laser beam reference information,

step b), obtaining the modulated laser beam information of the sample to be measured,

and c), calculating the laser beam reference information and the laser beam information modulated by the sample to be detected to obtain the nonlinear optical parameters.

14. The method of measurement according to claim 13, wherein step a) is before or after step b).

15. The measurement method of claim 13, wherein the measurement system comprises at least a second lens and a data recording element.

16. The measuring method according to claim 15, wherein in the step a), when the sample to be measured is not placed, the data recording element obtains laser beam reference information, and the laser beam reference information is a first laser spot; and b), after the sample is placed and a proper position is selected by the microscopic imaging system, the data recording element acquires the modulated laser beam information of the sample to be detected, and the modulated laser beam information of the sample to be detected is a second laser spot.

17. The measurement method according to claim 13, wherein the measurement method further comprises, before step b:

and d), placing a sample, and adjusting the position of the loading platform through the auxiliary focusing system to image the sample.

Technical Field

The invention relates to the field of optical parameter measurement, in particular to a measuring device and a measuring method for nonlinear optical parameters.

Background

The optical nonlinear material has a great application prospect in the field of optoelectronic devices such as optical switches and the like, and therefore, the optical nonlinear material is widely researched. A wide variety of materials are used in nonlinear optical research, from inorganic materials, organic materials to semiconductor materials, and from large-sized materials to small-sized materials. Nonlinear optics has developed to date, and more than ten methods for measuring nonlinear refractive index have emerged, such as nonlinear interferometry, degenerate four-wave mixing, self-diffraction, ellipsometry, Z-scanning, etc., all of which have their own advantages and disadvantages.

In 1996, Boudebs et al first proposed a 4F phase coherent imaging method to measure the optical Nonlinear refractive index of a material (BOUDEBS.G, CHIS.M, BOURDIN.J.P. "Third & order reflectivity measurements by Nonlinear image processing", J.Opti.Soc.Am.B, 1996,13: 1450-. The method has the advantages of single-pulse measurement, simple optical path, no need of sample movement and the like, but has certain requirements on the size of the measured material sample, the measurement area of the material sample cannot be determined, and the material with the size below millimeter level cannot be measured.

Disclosure of Invention

The invention provides a nonlinear optical parameter measuring device based on a 4f phase coherent imaging system, which can accurately measure the nonlinear optical parameters of micro-nano materials.

The measuring device provided by the invention comprises a laser beam modulation system, a measuring system and a microscopic imaging system, wherein the laser beam modulation system and the measuring system form a 4f phase coherent imaging system, a laser beam respectively enters the measuring system and the microscopic imaging system after passing through the spectroscope, and the spectroscope is a transmission-reflection mirror. .

The laser beam respectively enters the measuring system and the microscopic imaging system after passing through the spectroscope, the spectroscope is a transmission-reflection mirror, and the spectroscope is positioned behind a Fourier plane of the 4f phase coherent imaging system.

Preferably, the microscopic imaging system comprises a microscopic imaging lens group and an imaging element, the microscopic imaging lens group is a microscopic imaging lens group with adjustable imaging scale, and the microscopic imaging lens group at least comprises 2 lenses.

Preferably, the part of the 4f phase coherence measuring device before the fourier plane is a laser beam modulation system, which at least comprises a phase diaphragm and a first convex lens, and the distance from the phase diaphragm to the first convex lens is equal to the focal length of the first convex lens.

Preferably, the measuring system comprises at least a second lens and a data recording element, the distance of the data recording element to the second convex lens being equal to the focal length of the second convex lens; the imaging element and/or the data recording element is one of a CCD, a LCoS, or a DMD.

Preferably, a reflective mirror is further disposed between the laser beam modulation system and the beam splitter.

Preferably, the Fourier plane position of the 4f phase coherent measurement device is an object carrying platform, the object carrying platform is a three-dimensional adjustable support, the adjustment precision is 0.1 micron, the adjustment range is 0-20 mm, preferably, the adjustment precision of the object carrying platform is 10nm, and the adjustment range is 0-2 mm.

Preferably, the system further comprises an auxiliary focusing system, wherein the auxiliary focusing system comprises an illumination light source, an aperture and a transflector, the transflector is arranged between the data recording element and the second convex lens, and the aperture is imaged on the Fourier plane position of the 4f phase coherent imaging system through the transflector and the second convex lens.

The invention also provides a nonlinear optical parameter measuring method based on the 4f phase coherent imaging system, which comprises the following steps:

step a), obtaining laser beam reference information,

step b), obtaining the modulated laser beam information of the sample to be measured,

and c), calculating the laser beam reference information and the laser beam information modulated by the sample to be detected to obtain the nonlinear optical parameters.

Preferably, said step a) is before or after step b).

Preferably, the measurement system comprises at least a second convex lens and a data recording element.

Preferably, in the step a), when the sample to be detected is not placed, the data recording element acquires laser beam reference information, wherein the laser beam reference information is a first laser spot

Preferably, in the step b), after the sample is placed and a proper position is selected by the microscopic imaging system, the modulated laser beam information of the sample to be measured is acquired by the data recording element, and the modulated laser beam information of the sample to be measured is the second laser spot.

Preferably, the measuring method further comprises a step d) of placing a sample, and adjusting the position of the objective platform through an auxiliary focusing system to image the sample before the step b).

The invention adds the microscopic imaging system on the basis of the 4f phase coherent imaging system, can observe the testable range of the sample to be tested and the dynamic process of the light spot of the laser beam on the sample to be tested through the microscopic imaging system, expands the size range of the sample to be tested, and enables the optical parameters of the sample below millimeters and even below micrometers to be accurately measured. The testable range of the sample to be tested can be observed, and the position of the light spot on the sample to be tested can be selected, so that the accuracy of test data can be ensured, and the measurement error is greatly reduced.

Drawings

FIG. 1 is a schematic view of a measuring device according to an embodiment of the present invention;

FIG. 2 is a schematic view of a measuring device according to another embodiment of the present invention;

FIG. 3 is a schematic diagram of a light spot of laser beam information modulated by a phase stop according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a light spot of laser beam information modulated by a sample to be measured in an embodiment of the present invention;

FIG. 5 is a schematic view of a measuring device according to another embodiment of the present invention.

Wherein:

1 a laser beam; 2, a phase diaphragm; 3 a first convex lens; 4, a reflector; 5, a loading platform; 6 a spectroscope; 7 a first microlens; 8 second microlenses; 9 an imaging element; 10 a second convex lens; 11 a data recording element; 12 an auxiliary focusing system; 12-1 transflector; 12-2 pores; 12-3 illumination light source

Detailed Description

The foregoing and other technical and scientific aspects, features and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment, which is to be read in connection with the accompanying drawings. Directional terms as referred to in the following examples, for example: up, down, left, right, front or rear, etc., are simply directions with reference to the drawings. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting. The invention is described in further detail below with reference to the accompanying drawings:

fig. 1 is a schematic diagram of a measuring apparatus for measuring nonlinear optical parameters based on a 4f phase coherent imaging system according to an embodiment of the present invention. The measuring device comprises a phase diaphragm 2, a first convex lens 3, an object stage 5, a transmission-reflection mirror 6, a first micro lens 7, a second micro lens 8, an imaging device 9, a second convex lens 10 and a data recording element 11; the focal lengths of the first convex lens 3 and the second convex lens 10 are both f, wherein the phase diaphragm 2 and the first convex lens 3 form a laser beam modulation system; a second convex lens 10 and a data recording element 11 measurement system; the first microscope lens 7 and the second microscope lens 8 form a microscope imaging lens group, and the microscope imaging lens group and the imaging element 9 form a microscope imaging system, wherein the imaging proportion range of the microscope imaging lens group is 1-0.1. The imaging element 9 and the data recording element 11 may be one of a CCD, an LCoS, or a DMD, respectively, which is merely exemplary and not limited thereto.

In this embodiment, the laser beam modulation system and the measurement system together form a 4f phase coherent imaging system, where the optical path from the phase stop 2 to the first convex lens 3 is f, the optical path from the first convex lens 3 to the sample to be measured on the stage 5 is f, the optical path from the sample to be measured on the stage 5 to the second convex lens 10 is f, and the optical path from the second convex lens 10 to the data recording element 11 is f. The object carrying platform 5 is located on a Fourier plane of the 4f phase coherent imaging system, the object carrying platform 5 is a three-dimensional adjustable support, the adjustment precision is 0.1 micrometer, the adjustment range is 0-20 millimeters, in other embodiments, the adjustment precision can be adjusted to 10nm or less according to requirements, and the adjustment range is 0-2 millimeters. The laser beam 1 respectively enters a measuring system and a microscopic imaging system through a transmission-reflection mirror 6 after the Fourier plane, and the transmission reflectance of the transmission-reflection mirror 6 is 1: 9.

when the nonlinear optical parameters are measured, laser beam reference information is required to be obtained, laser beam information modulated by a sample to be measured is obtained, and the nonlinear optical parameters are obtained by calculating the laser beam reference information and the laser beam information modulated by the sample to be measured. The step of obtaining the laser beam reference information may be before or after the step of obtaining the modulated laser beam information of the sample to be measured. Specifically, the laser beam reference information is obtained, that is, under the condition that a sample to be detected is not placed, the light spot of the laser beam information modulated by the phase diaphragm 2 is directly recorded through the data recording element 11; the sample to be measured is placed on the objective table 5, the position of the laser spot on the surface of the sample to be measured is observed through the imaging element 9, the position of the objective table 5 is adjusted, so that the laser beam is made to strike at the proper position of the sample to be measured, the data recording element 11 records the laser beam spot modulated by the sample to be measured at the moment, and the laser beam spot records the information modulated by the relevant diaphragm 2 and the sample to be measured at the moment. In an embodiment, the laser beam is 650nm laser, the pulse width is 190fs, the laser energy is 270nj, the sample is a ZnSe crystal, the laser spot of the obtained laser reference information can refer to fig. 3, the laser spot information of the obtained ZnSe crystal after modulating the laser beam can refer to fig. 4, the laser spot information of the laser beam in fig. 3 and fig. 4 is calculated, the method comprises the steps of respectively carrying out data processing on the central spot and the peripheral spots in fig. 3 and fig. 4 to obtain an energy distribution diagram of the laser spot which is not subjected to the ZnSe crystal and is irradiated on the data recording element 11 after being subjected to the ZnSe crystal, comparing the two experimental result diagrams to obtain a modulation result of the ZnSe crystal on the laser spot, and obtaining the size and the sign of the optical nonlinear refractive index of the ZnSe crystal through fitting.

Fig. 2 is a schematic diagram of a testing apparatus according to another embodiment of the present invention. In this embodiment, the same reference numerals as those in fig. 1 refer to the same elements, and the difference from the embodiment shown in fig. 1 is that the embodiment further includes a reflecting mirror 4, the reflecting mirror 4 is disposed between the first convex lens and the object stage 5, and in this embodiment, the laser beam modulation system, the reflecting mirror 4 and the measuring system together form a 4f phase coherent imaging system. By changing the direction of the optical axis, the positions of all parts of the testing device are more compact, and the size of the whole device is reduced.

Fig. 5 is a schematic view of a testing apparatus according to another embodiment of the present invention. In the embodiment, the same components are numbered as those in fig. 2, and the difference from the embodiment shown in fig. 2 is that the embodiment further includes an auxiliary focusing system 12, where the auxiliary focusing system 12 includes a transflective mirror 12-1, an aperture 12-2 and an illumination light source 12-3, the aperture 12-2 is made of black material as a whole, and an aperture is provided in the middle. The transflective mirror 12-1 is disposed on a light path of the measurement system, specifically, the transflective mirror 12-1 is disposed between the data recording element 11 and the second convex lens 10, the small hole 12-2 is disposed outside the light path of the measurement system, and a position of the small hole 12-2 is equivalent to a virtual image position of a theoretical position in the microscopic imaging system when the object platform 5 is used for measurement. The illumination light source 12-3 illuminates the aperture 12-2, and the aperture 12-2 is imaged on the Fourier plane of the 4f phase coherent imaging system through the transflector 12-1 and the second lens 10. During testing, a sample is placed on the object carrying platform 5, the object carrying platform 5 moves to the imaging position of the small hole 12-2, the sample on the object carrying platform 5 appears in the visual field of a microscopic imaging system at the moment, then the position of the object carrying platform 5 is finely adjusted to achieve an ideal imaging effect, and the position of the sample to be tested is accurately positioned at the moment.

The invention adds the microscopic imaging system on the basis of the 4f phase coherent imaging system, can observe the testable range of the sample to be tested and the dynamic process of the light spot of the laser beam on the sample to be tested through the microscopic imaging system, expands the size range of the sample to be tested, and enables the optical parameters of the sample below millimeters and even below micrometers to be accurately measured. The testable range of the sample to be tested can be observed, and the position of the light spot on the sample to be tested can be selected, so that the accuracy of test data can be ensured, and the measurement error is greatly reduced.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the invention, which is defined by the appended claims and all simple equivalent changes and modifications within the scope of the invention. Moreover, it is not necessary for any embodiment or claim of the invention to address all of the objects, advantages, or features disclosed herein. In addition, the abstract and the title of the invention are provided for assisting the retrieval of patent documents and are not intended to limit the scope of the invention. Furthermore, the terms "first", "second", and the like in the description or the claims are used only for naming elements (elements) or distinguishing different embodiments or ranges, and are not used for limiting the upper limit or the lower limit on the number of elements.