CN2397505Y - Optical fiber confocal scanning microscope - Google Patents

Abstract

A fiber confocal scanning microscope comprises an illumination beam input part A, a fiber scanning part B, a measurement positioning part C interlaced with the fiber scanning part B, a detection sampling part D and a control data acquisition processing part E. A, B, D and E constitute a fiber confocal scanning microscope, while A, B and C constitute a quasi-confocal small field microscope. In other words, a microscope of the utility model has the functions of two microscopes, namely, the function of microscopic scanning tomography and the function of primary imaging, that is, the function of self-positioning the measurement target. It is suitable for three-dimensional structure detection with nanometer depth and submicron width.

Description

Fiber Confocal Scanning Microscope

The utility model is an optical fiber confocal scanning microscope, which is suitable for three-dimensional structure detection with nanometer depth and submicron width.

Existing technology:

In the 1990s, the technology of using single-mode fiber instead of pinhole appeared. Since then, confocal scanning microscopy technology using fiber optic devices has developed rapidly. There are two reasons. One is to directly input the laser into the optical fiber to avoid the vibration generated by the laser cooling system; the other is to simplify the structure and make the scanning confocal system more compact. But there is no big improvement in performance. In 1996, the utility model patent applicant also provided a fiber optic confocal scanning microscope based on a single-mode fiber coupler (see the English version published in "China Laser" magazine: Fiber Optical Confocal Scanning Microscope Using Single mode Fiber Coupler, Chinese Journal of Laser, 1996, B5(1): 81). The instrument is very representative both in structure and performance.

The fiber optic confocal scanning microscope in the prior art has the following problems: (1) The detection target positioning problem. Since the fiber scanning microscope is point-imaging, it is scanned and sampled and topographically imaged by a computer. This structure itself cannot locate small targets in a wide range. The solution to this problem is generally to complete the positioning by means of an ordinary optical microscope. This requires the combination of optical fiber devices and ordinary optical microscopes to achieve positioning observation. So it is not out of the ordinary microscope mode, the instrument is bulky, and the resolution cannot be further improved. In this instrument, it is nothing more than using optical fiber to replace the original small hole, and there is no more novelty in the overall structure. (2) At the detection end, the optical fiber is used as a filter hole, and the light beam emitted by the fiber coupler is directly input into the detector, and the detection resolution of the gray fineness is restricted by the resolution of the detector. (3) In terms of data acquisition, directly use 3D scanning sampling to perform 3D image topology, which takes a long time for sampling and brings large errors. Its spatial resolution is limited by the sampling step size.

The purpose of this utility model is:

First, keep the characteristics of lightness and stability of optical fiber devices, which not only solves the problem of positioning the detection range of the point scanning microscope in the prior art, but also maintains the advantages of compactness, lightness and stability of the original instrument, and achieves the practical purpose of multi-function.

Second, further improve the resolution of the fiber confocal scanning microscope, especially the longitudinal resolution, so that this type of instrument can reach nanometer resolution and realize real super-resolution. It can be widely used in molecular biology, optical storage devices, and VLSI detection.

Microscope of the present utility model, its light path as shown in Figure 1. It includes an illumination beam input part A, an optical fiber scanning part B, a measurement positioning part C, a detection sampling part D and a control data acquisition and processing part E. Wherein the illuminating beam input part A includes along the direction along which the light beam emitted by the laser 1 as the light source advances, a coupling objective lens 2 and a fiber coupler 4 are placed in sequence, and the first output end _O1 of the fiber coupler 4 has a refractive index Matching liquid container3. The optical fiber scanning part B includes a beam collimating mirror 5, a sampling objective lens 6 and a measured sample 7 placed on the focal plane f of the sampling objective lens 6 along the advancing direction of the output beam at the second output port _O2 of the fiber coupler 4 ; There is a measurement positioning part C interlaced with the fiber scanning part B. The measurement positioning part C includes a sample objective lens 6, a beam splitter 9, and a beam splitter on the direction of the light beam reflected back from the sample 7 on the out-of-focus plane P of the sample objective lens 6 along the sample adjustment frame 17. 9 In the forward direction of the reflected light beam, there are magnifying eyepiece 10 and observation screen 11 in turn; the detection sampling part D includes along the third output port O of the fiber coupler _4. On the forward direction of the outgoing light beam, there are in turn a magnifying eyepiece 16 and a belt The detector 15 of the detector power supply 14; the control data acquisition processing part E includes a sample adjustment rack 17 made of piezoelectric ceramics with a piezoelectric ceramic driver (PZT) 8 for placing the measured sample 7, and the piezoelectric ceramic driver 8 passes through the The power supply 13 with the balancer is connected with the computer 12 . The computer 12 is also connected to the detector 15 in the detection sampling section D at the same time.

The utility model has two kinds of microscope functions as the above-mentioned structure, one is microscopic scanning tomography imaging function; the other is primary imaging function. The light path is shown in Figure 1. Part A is the lighting beam input part. The light beam emitted by the laser 1 as the light source is sequentially input into the input end i coupling the objective lens 2 and the fiber coupler 4 , and enters into the fiber coupler 4 . The returned probe light and stray light are emitted from the first output end _O1 of the fiber coupler 4, and are emitted into the container 3 containing the refractive index matching liquid. Part B is the fiber scanning part. The light beam output from the second output port O2 of the fiber coupler ₄ enters the beam collimating mirror 5, and then the sampling objective lens 6 further focuses the light spot emitted by the fiber into a small light spot and projects it on the sample 7 on the focal plane f to perform the calibration. The detection of the structure of test sample 7. Part D is the detection sampling part. Wherein 14 is the power supply of the detector, the detection light output by the third output port _O3 of the fiber coupler 4 is first amplified by the magnifying eyepiece 16 and then input to the receiving surface of the detector 15, and the detector 15 will convert the light information into Electronic information, input to the computer 12 of the E section. Part E is the control data acquisition and processing part. The measured sample 7 is supported by a sample adjustment frame 17 driven by a piezoelectric ceramic driver (PZT) 8 capable of precise scanning, and the scanning step is controlled by a computer 12, which also controls the sampling of part D and performs data processing. Computer 12 controls PZT power supply 13 with balancer. Part C is the measurement and positioning part. When the positioning operation is performed, the light beam from the out-of-focus plane P is reflected back from the measured sample 7 , passes through the sampling objective lens 6 and the beam splitter 9 , enters the magnifying eyepiece 10 , and is imaged on the observation screen 11 . Part C includes the sampling objective lens 6 of part B. First, in order to image the detected portion of the sample 7 under test, the sample 7 under test must be placed on the defocused plane P of the probe light. When the measured sample 7 is placed on the defocus plane P, a bundle of divergent light returns to the sampling objective lens 6 from the surface of the measured sample 7, and after the sampling objective lens 6, the beam splitter 9 is used to reflect less than 10% of the light , enter the magnifying eyepiece 10 to enlarge, and image on the observation screen 11 at one time. The viewing screen 11 may be a direct viewing screen, or a receiving surface of a detector. Imaging is performed directly on the area near the focal point of the measured sample 7 , that is, the out-of-focus plane P. This split beam forms a quasi-confocal small field-of-view primary imaging microscope for use in positioning for point-scanning microscopes. After being positioned, the tested sample 7 is pushed to the focal plane f of the sampling objective lens 6 for confocal imaging. The probe light returned from one point of the tested sample 7 passes through the transmitted light of the beam splitter 9, is coupled into the fiber coupler 4 again, is output by the third output port _O3 of the fiber coupler 4, enters the magnifying eyepiece 16, and forms an image on the receiving face of the detector 15. Perform scanning imaging.

The microscope can be divided into two parts according to functions, one part is a fiber confocal scanning microscope composed of A, B, D and E, and the other part is a quasi-confocal small field microscope composed of A, B and C. Compared with the optical path of the optical fiber confocal scanning microscope in the prior art, the optical path of the present utility model only utilizes the beam splitter in the measurement positioning part C under the premise of maintaining the compact structure of the original optical fiber confocal scanning microscope 9 beam splitters form a new quasi-confocal microscope with a small field of view, which enables it to have the function of a positioning microscope. The localization microscope itself is also a quasi-confocal high-resolution microscope with submicron lateral resolution. It is organically combined with the fiber confocal scanning microscope. The optical fiber confocal scanning microscope in the prior art uses the point scanning imaging form and cannot image at one time, so it does not have the function of direct observation and positioning of the observation screen 11 . The utility model includes A, B, and C small-field microscopes with a primary imaging structure, which can be directly observed with human eyes on the observation screen 11, and is pre-positioned for the optical fiber confocal scanning microscope for point scanning imaging. In operation, in order to image the sample 7 under test, it must move some distance in the axial direction, that is, move to a position away from the focal plane P and leave the Fraunhofer diffraction area. Otherwise, what is observed on the observation screen 11 is the Fraunhofer diffraction pattern instead of the image of the sample surface. The optical fiber confocal scanning microscope of the utility model has the measurement and positioning part C, just as the person who launches the shell has a telescope. He can select targets in the wide field of vision he sees. Conversely speaking, without a telescope, it will be difficult to determine the target. The utility model adds this important function to the optical fiber confocal scanning microscope without destroying its compact and light structure. This will further develop its application in material science, biomedicine and even life science and other disciplines.

The above-mentioned laser 1 as a light source is a solid-state laser, or a gas laser, or a semiconductor laser, or other coherent light sources.

The above-mentioned sample adjusting rack 17 is a three-dimensional adjusting rack.

The utility model has the advantages of:

1. Since the measurement and positioning part C is interlaced with the optical fiber scanning part B in the microscope of the present invention, this makes a microscope of the present invention have the functions of two microscopes simultaneously. It not only has the advantages of fiber scanning microscope, but also has the function of quasi-confocal small field microscope for its positioning. Therefore, the microscope of the utility model not only has the characteristics of compact and light structure, but also has the function of self-positioning, and is easy to operate, stable and reliable, practical and easy to popularize.

2. The optical fiber scanning part B of the utility model can topologically super-high-resolution images, and can use part C to perform quasi-confocal primary imaging. On the one hand, the small-field quasi-confocal microscope positions the measurement range of the fiber-optic confocal scanning microscope, and on the other hand, it can also be used to directly detect submicron microstructures. The advantages of this structure are as follows: ① Since most of these two microscopes have a common optical path structure, the optical path has strong anti-interference and is suitable for various environments. ②The primary imaging area surrounds the detection point of the fiber optic confocal scanning microscope, with a small field of view and accurate positioning. ③Primary imaging microscope is illuminated by coherent light, the image is clear, and it is easy to locate the edge of the image.

3. The advantage of adding the magnifying eyepiece 16 in front of the detector 15 is to increase the fineness of the detection signal. If a 600-800nm laser is used as the probe light, the diameter of the light spot emitted by the fiber is only about 5 μm. However, the resolution of the general detector 15 is equal to or greater than this order of magnitude. Magnifying the light spot by more than 10 times and imaging it on the receiving surface of the detector 15 will relatively increase the resolution of the detector 15 by 10 to 20 times. Increased probing granularity. Improved overall instrument resolution.

Description of drawings:

FIG. 1 is a schematic diagram of the optical path of the fiber optic confocal scanning microscope of the present invention.

Fig. 2 is a graph showing the results of the blazed grating detection of the tested sample 7 by using the microscope of the utility model in embodiment 1.

Fig. 3 is embodiment 2, utilizes the microscope of the present utility model to test sample 7 is the two-dimensional curve chart of the pregroove detection result of coated optical disc and the prior art detection result comparison. In the figure, the solid line—represents the detection result using the microscope of the utility model, and the dotted line——represents the detection result using the scanning near-field optical microscope of the prior art. The dotted line—·—indicates the results detected by the prior art atomic force microscope.

Example 1:

The structure shown in Figure 1, the laser 1 is a helium-neon laser, the detector 15 is a CCD detector (the distance between images is 10 μm), the parameter of the sampling objective lens 6 is 40×, the NA is 0.65, and the parameter of the beam collimator 5 is 4 ×, NA is 0.1, and the fiber coupler 4 is a single-mode fiber matched with the He-Ne laser beam. Its piezoelectric ceramic driver PZT8 moves with a resolution of 5nm. Test sample 7 is a blazed grating. Detect the shape and angle of the reticle. Its fineness is 1200 lines/mm, and its blaze angle is 22.3 degrees. Utilize the detection result of the utility model: its fineness is: 1200±50 lines/mm, the detection data includes the error caused by the manufacture and damage of the grating. Its blaze angle is 22.5±0.5 degrees. The utility model also detects the height of the reticle, and the result is 350±55nm. The test results showed that this grating was eliminated, and its surface was severely damaged. A cross-section of the measurement results is shown in Figure 2.

Example 2:

Still using the above-mentioned structure and parameters of each optical element, the tested sample 7 is an optical disc coated with a film layer, and its pre-groove is tested. The production data of the tested sample 7 are: the groove width is 0.4 μm, the groove spacing is 1.64±0.05 μm, and the groove height is 92±3 nm. The detection result (solid line in FIG. 3 ) is better than the detection results of the prior art atomic force microscope (dotted line in FIG. 3 ) and near-field scanning optical microscope (dashed line in FIG. 3 ). Shown in Figure 3.

Claims (3)

1. A fiber optic confocal scanning microscope, comprising an illumination beam input part (A), an optical fiber scanning part (B), a detection sampling part (D) and a control data acquisition processing part (E), wherein the illumination beam input part (A) Including a coupling objective lens (2) and a fiber coupler (4) arranged sequentially along the direction in which the light beam emitted by the laser (1) advances, and a container placed on the first output end (O ₁ ) of the fiber coupler (4) The container (3) of the refractive index matching liquid; the optical fiber scanning part B includes a beam collimating mirror ( ₅ ) and a sampling objective lens ( 6) and the measured sample (7) placed on the focal plane (f) of the sampling objective lens (6); the detection sampling part (D) includes the advancement of the outgoing light beam at the third output end (O ₃ ) of the fiber coupler (4) A detector (15) with a detector power supply (14) is placed in the direction; the control data acquisition and processing part E includes a sample made of piezoelectric ceramics with a piezoelectric ceramic driver (8) for placing the measured sample (7) The adjustment frame (17), the piezoelectric ceramic driver (8) is connected with the computer (12) through the power supply (13) with a balancer, and the computer (12) is also connected with the detector (15) in the detection sampling part (D) Connected, it is characterized in that there is a measurement positioning part (C) interlaced with the optical fiber scanning part (B), and the measurement positioning part (C) includes placing on the sample adjustment frame (17) along the sampling objective lens (6) On the out-of-focus surface (P) of the measured sample (7) in the direction of the light beam reflected back, there are in turn a sampling objective lens (6), a beam splitter (9), and in the direction of the light beam reflected by the beam splitter (9), There are magnifying eyepieces (10) and observation screens (11) in sequence; in the detection sampling part (D), between the third output end (O ₃ ) of the fiber optic coupler (4) and the receiving surface of the detector (15) A magnifying eyepiece (16) is provided. 2. The optical fiber confocal scanning microscope according to claim 1, characterized in that the reflectance of the beam splitter (9) in the measurement positioning part (C) is less than 10%. 3. The optical fiber confocal scanning microscope according to claim 1, characterized in that the observation screen (11) in the measurement positioning part (C) is a direct observation screen, or a receiving surface of a detector.

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