JP2017009765A - Scanning microscope and method of generating pixel data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for generating highly reliable pixel data without excessively complicating a device configuration.SOLUTION: A scanning microscope 100 detects light from a sample S scanned by a two-dimensional scanning mechanism 4 using an optical detector 13, and oversamples an analog signal generated by the optical detector 13 using an A/D converter 16. The scanning microscope 100 has a pixel data generator 21 configured to generate pixel data corresponding to each region of the sample S on the basis of a plurality of digital signals output by the A/D converter 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for generating pixel data of a scanned image.

  A confocal microscope is a type of scanning microscope that scans a sample with light, and is currently widely used in various applications. A confocal microscope can measure a three-dimensional shape in a non-contact manner by utilizing its optical sectioning effect. For this reason, it is also used as a measuring device for measuring a three-dimensional shape.

  When a confocal microscope is used as a measuring device, there is an advantage that there is no risk of damaging the sample as compared with a contact-type measuring device that traces the sample with the tip of a stylus. On the other hand, when measuring a sample with low reflectivity or when measuring a sample with a greatly inclined surface, the detected light quantity may be insufficient and the S / N ratio may deteriorate. For this reason, in the confocal microscope, various techniques for improving the S / N ratio and performing highly reliable measurement have been proposed.

  For example, Patent Document 1 describes a technique for reducing noise by integrating image signals when the reflectance of the sample is low and the image signal contains a lot of noise. Patent Document 2 describes a technique for obtaining an omnifocal image and height information based on a signal determined to be more reliable by comparing signals acquired with different pinhole diameters.

JP-A-9-212333 JP 2009-175682 A

  However, in Patent Document 1, since image signals of different frames are used, a larger time difference occurs between timings of acquiring image signals as the number of integration increases. The occurrence of such a time difference is undesirable from the viewpoint of data reliability. Moreover, in patent document 2, since the several detection system from which a pinhole diameter differs is required, the structure of an apparatus becomes complicated and the whole apparatus will become expensive.

  In view of the above circumstances, an object of the present invention is to provide a technique for generating highly reliable pixel data without excessively complicating the device configuration.

  One aspect of the present invention includes a scanning optical system including a scanning unit that scans a sample with light, a light detector that detects light from the sample scanned by the scanning unit, and outputs an analog signal; A sampling unit that oversamples an analog signal output from the photodetector and outputs a digital signal, and pixel data corresponding to each region of the sample is generated based on a plurality of digital signals output from the sampling unit Provided is a scanning microscope provided with pixel data generating means.

  Another aspect of the present invention is a pixel data generation method for a scanning microscope comprising a scanning means and a photodetector, wherein light from a sample scanned by the scanning means is detected by the photodetector, and the light Provided is a pixel data generation method for over-sampling an analog signal output from a detector and generating pixel data corresponding to each region of the sample based on a plurality of digital signals obtained by over-sampling.

  According to the present invention, it is possible to generate highly reliable pixel data without excessively complicating the device configuration.

1 is a diagram illustrating a configuration of a scanning microscope 100 according to Example 1. FIG. It is the figure which showed an example of the scanning method. It is the figure which showed an example of the relationship between a pixel area and pixel data. It is the figure which showed another example of the relationship between a pixel area and pixel data. It is a flowchart of a height information generation process. It is the figure which showed an example of the IZ curve. FIG. 3 is a block diagram illustrating an example of a configuration of a clock generation circuit 15 according to the first embodiment. It is a figure which shows the relationship between the sampling clock concerning Example 1, and a scanning position. It is a figure which shows the relationship between the sampling clock concerning Example 2, and a scanning position.

  FIG. 1 is a diagram illustrating the configuration of a scanning microscope 100 according to the present embodiment. FIG. 2 is a diagram illustrating an example of a scanning method using the scanning microscope 100. The scanning microscope 100 is a laser scanning microscope that scans the sample S with a light spot on which laser light is condensed, and is also a confocal microscope including a confocal optical system. The scanning microscope 100 is used as, for example, a three-dimensional measurement apparatus that generates height information (including surface roughness information) of the sample S. In this specification, the position on the sample S where the light spot is formed is referred to as a scanning position.

  As shown in FIG. 1, the scanning microscope 100 includes a microscope main body 10, a computer 20, a display device 30, and an input device 40. The microscope main body 10 includes a scanning optical system, a photodetector 13, a scanning drive control circuit 14, a clock generation circuit 15, an A / D converter 16, a displacement meter 17, and a focus moving mechanism 18. The scanning optical system includes a laser light source 1, a mirror 2, a half mirror 3, a two-dimensional scanning mechanism 4, a mirror 5, a lens 6, a revolver 7, an objective lens 8, a stage 9, a lens 11, and a confocal stop 12.

  The two-dimensional scanning mechanism 4 is a scanning unit that scans the sample S with the laser light from the laser light source 1 and is controlled by the scanning drive control circuit 14. The two-dimensional scanning mechanism 4 includes a scanner 4a that is a scanning unit that scans the sample S in the X direction orthogonal to the optical axis of the objective lens 8, and the sample S in the Y direction that is orthogonal to the optical axis of the objective lens 8 and the X direction. A scanner 4b as scanning means for scanning is provided. For example, the scanner 4a is a resonant scanner, and the scanner 4b is a galvano scanner. Resonant scanners can scan faster than galvano scanners. However, the speed is not constant during the period of the periodic motion, and the speed change is expressed by a sine function. That is, the sample S is scanned at non-constant speed. On the other hand, although the galvano scanner is generally slower than the resonant scanner, it can scan the sample S at a constant speed during the periodical motion. The two-dimensional scanning mechanism 4 composed of a resonance scanner and a galvano scanner is suitable for raster scanning that requires scanning in one direction at a higher speed than in the other direction.

  The confocal stop 12 is a stop in which a pinhole is formed. The confocal stop 12 is arranged so that a pinhole is positioned at a position optically conjugate with the front focal position of the objective lens 8 in order to block light reflected at a position other than the front focal position of the objective lens 8. ing. For example, the confocal stop 12 is disposed on the rear focal plane of the lens 11.

  The photodetector 13 is a photoelectric conversion element that detects light from the sample S scanned by the two-dimensional scanning mechanism 4 and outputs an analog signal corresponding to the detected light intensity. The photodetector 13 is, for example, a photomultiplier tube (PMT).

  The scanning drive control circuit 14 is a circuit that controls the two-dimensional scanning mechanism 4. For example, the scanning drive control circuit 14 controls the two-dimensional scanning mechanism 4 so that the light spot moves along the locus 19 shown in FIG. 2, that is, the raster scan is performed. Hereinafter, the cycle of line scanning (scanning in the X direction in FIG. 2) constituting the raster scan is referred to as a scanning cycle. Further, the scanning drive control circuit 14 outputs a signal indicating the scanning timing of the two-dimensional scanning mechanism 4 (hereinafter referred to as a scanning timing signal) to the clock generation circuit 15. The scanning timing signal is, for example, a signal that indicates the start timing of each line scan in the X direction by the scanner 4a.

  The clock generation circuit 15 is a clock generation unit that generates a sampling clock so that the sampling positions on the sample S move at equal intervals and outputs the sampling clock to the A / D converter 16. That is, the sampling clock generated by the clock generation circuit 15 is a sampling clock synchronized with the scanning speed of the scanner 4a. The faster the scanning speed, the shorter the clock interval, and the slower the scanning speed, the longer the clock interval. . In this specification, the sampling position refers to the scanning position when sampling is performed.

  The clock generation circuit 15 generates a sampling clock synchronized with the scanning speed based on, for example, the scanning timing signal received from the scanning drive control circuit 14 and the speed waveform information of the scanner 4a. The velocity waveform information is information indicating how the moving speed of the light spot formed on the sample S changes during the period in which the scanner 4a scans the sample S, and more specifically. 1 is information on the moving speed of the light spot at each timing during one scanning cycle. The sampling position at each timing can be specified based on the scanning timing signal and velocity waveform information.

  The A / D converter 16 is a sampling unit that oversamples the analog signal output from the photodetector 13 and outputs a digital signal corresponding to the light intensity detected by the photodetector 13. The digital signal indicates the luminance value at the sampling position. The A / D converter 16 oversamples the analog signal according to the sampling clock generated by the clock generation circuit 15. Here, oversampling means that sampling is performed more times than the number of pixels in the horizontal direction during one cycle of line scanning performed by the scanner 4a. The number of pixels in the horizontal direction is the maximum number of pixel data generated from a signal obtained by scanning one line. In the scanning microscope 100, the number of pixels is based on the signal obtained by scanning one line. This is the number of pixel data generated by the pixel data generation unit 21. The A / D converter 16 may A / D convert the time integration of the input signal.

  The displacement meter 17 is a means for measuring the amount of movement of the objective lens 8 that moves together with the revolver 7 in the optical axis direction. The displacement meter 17 is configured to output the amount of movement of the objective lens 8 in the optical axis direction to the computer 20. The focal point movement mechanism 18 is a means for moving the revolver 7 in the optical axis direction. The focal point movement mechanism 18 may be, for example, a stepping motor or a piezo element. Since the focal point moving mechanism 18 may be any mechanism that changes the distance between the objective lens 8 and the sample S, the stage 9 may be moved in the optical axis direction instead of the revolver 7. In that case, the displacement meter 17 is configured to measure the amount of movement of the stage 9 in the optical axis direction.

  In the microscope body 10, the laser light emitted from the laser light source 1 reflects the mirror 2 and enters the mirror 5 via the half mirror 3 and the two-dimensional scanning mechanism 4. The laser beam reflected by the mirror 5 in the direction of the optical axis of the objective lens 8 is enlarged to a predetermined light beam diameter by the lens 6 and forms a light spot on the sample S arranged on the stage 9 by the objective lens 8. The laser light reflected from the sample S enters the objective lens 8 again, and enters the half mirror 3 through the lens 6, the mirror 5, and the two-dimensional scanning mechanism 4. The laser beam reflected by the half mirror 3 is collected by the lens 11 and detected by the photodetector 13 through a pinhole formed in the confocal stop 12. The scanning microscope 100 obtains a digital signal at each sampling position (that is, a luminance value at each sampling position) by repeating sampling by the A / D converter 16 while moving the scanning position by the two-dimensional scanning mechanism 4. Can do.

  The computer 20 includes an auxiliary storage device such as a CPU, a memory, and a hard disk. When the CPU loads the program loaded in the memory, the CPU operates as the pixel data generation unit 21 and the display data generation unit 22. That is, the computer 20 includes a pixel data generation unit 21 and a display data generation unit 22. The computer 20 generates pixel data based on the output signal from the microscope body 10, and generates height information and omnifocal image data of the sample S based on the generated pixel data. The generated data is recorded in the auxiliary storage device.

  The pixel data generation unit 21 generates pixel data corresponding to each region (pixel region) of the sample S based on a plurality of digital signals output from the A / D converter 16. Each of the plurality of pixel data generated by the pixel data generation unit 21 is preferably generated based on the same number of digital signals.

  It is desirable that pixel data corresponding to a certain pixel region is generated based on a plurality of digital signals acquired at sampling positions in the pixel region. For example, in the case of generating 1024 pixel pixel data in a horizontal direction per line by performing 2048 samplings during one scanning cycle, the pixel data generating unit 21 includes the first pixel as shown in FIG. Pixel data is generated based on the digital signals acquired by the first and second samplings, pixel data of the second pixel is generated based on the digital signals acquired by the third and fourth samplings, and N It is desirable to generate the pixel data of the pixel based on the digital signals acquired by the 2N-1 and 2N samplings.

  Further, pixel data corresponding to a certain pixel area may be generated based on a plurality of digital signals acquired at a sampling position in the pixel area and a sampling position in a pixel area adjacent to the pixel area. For example, in the case of generating 1024 pixel pixel data in a horizontal direction per line by performing 2048 samplings during one scanning cycle, the pixel data generating unit 21 includes the second pixel as shown in FIG. Pixel data is generated based on the digital signal acquired by sampling from the second time to the fifth time, and pixel data of the N pixel is generated based on the digital signal acquired by sampling from the 2N−2th time to the 2N + 1th time. It may be generated. In this case, the pixel data of the first pixel is obtained by estimating the digital signal at the sampling position of the 0th time by interpolation calculation, and based on the estimated digital signal and the digital signal acquired by the sampling from the first time to the fifth time, Pixel data for the first pixel may be generated.

  Note that the pixel data may be generated so that the ratio of noise components (S / N ratio) included in the pixel data is smaller than the ratio of noise components included in each of the plurality of digital signals. That is, it suffices if the noise is reduced, and the pixel data generation unit 21 can employ any calculation for the purpose of noise removal. Specifically, the pixel data generation unit 21 may generate pixel data by statistically processing a plurality of digital signals such as mode value selection, maximum value selection, and averaging. Further, the pixel data generation unit 21 may generate pixel data by low-pass filter processing. The noise removal effect will be described by taking averaging as an example. Since the noise is considered to be generated in a normal distribution, the noise can be attenuated to 1 / √N by averaging N digital signals. Moreover, the ratio of noise can be reduced as the number of samplings is increased.

  Further, the pixel data may be generated such that the dynamic range of the pixel data is larger than each dynamic range of the plurality of digital signals. Specifically, the pixel data generation unit 21 may generate pixel data by integrating a plurality of digital signals. In this case, pixel data having a wide dynamic range exceeding the dynamic range limited by the A / D converter 16 can be generated. Further, when the amount of light incident on the photodetector 13 is small, a signal corresponding to the amount of light (hereinafter referred to as a minute signal) does not always occur, but occurs probabilistically. By sampling and accumulating more, the possibility of catching minute signals that occur stochastically increases. Since this point also contributes to the expansion of the dynamic range, the substantial resolution can be improved. The same effect can be obtained when the A / D converter 16 has an integration circuit and samples the temporal integration value of the analog signal. Further, the pixel data generation unit 21 is configured to switch and execute a calculation (for example, integration) for extending the dynamic range and a calculation (for example, averaging) for suppressing noise based on a user instruction. Also good.

  The display data generation unit 22 generates display pixel data from the pixel data generated by the pixel data generation unit 21. The display data generation unit 22 may output the pixel data generated by the pixel data generation unit 21 as it is as display pixel data. One display pixel data may be generated from two or more pieces of pixel data generated by the pixel data generation unit 21 according to the number of pixels of the display device 30.

  The display device 30 is a display unit that displays an image of the sample S based on image data that is a collection of pixel data generated by the computer 20. The display device 30 may be, for example, a liquid crystal display or an organic EL display. The display device 30 may display an image of the sample S based on the latest image data each time the computer 20 generates image data, or may display various information other than the image of the sample S. Good.

  The input device 40 is an input device that inputs a command corresponding to a user operation to the computer 20. The input device 40 is, for example, a mouse, a keyboard, a touch panel, or the like.

  FIG. 5 is a flowchart of height information generation processing performed in the scanning microscope 100. FIG. 6 is a diagram showing an example of the IZ curve. Hereinafter, a method for generating the height information of the sample S will be described with reference to FIGS. 5 and 6.

  First, the scanning microscope 100 performs oversampling while scanning the sample S in the X direction (step S1). Here, the photodetector in which the A / D converter 16 detects light from the sample S according to the sampling clock while the light spot moves in the X direction on the sample S by line scanning performed by the two-dimensional scanning mechanism 4. The analog signal from 13 is oversampled. Since the sampling clock is generated so that the sampling positions move on the sample S at equal intervals, in step S1, the luminance values of the sample are spatially measured at equal intervals.

  Next, the scanning microscope 100 generates pixel data for one line (step S2). Here, the pixel data generation unit 21 generates pixel data of each region on the line of the sample S based on a plurality of digital signals output from the A / D converter 16. For example, when 2048 samplings are performed during one line scanning in step S1, pixel data of one pixel is generated based on two digital signals obtained by two different samplings, and a total of 1024 pixels Pixel data is generated. Note that although an example in which step S1 and step S2 are sequentially performed is shown, pixel data may be generated every time a necessary number of digital signals are generated without waiting for the end of line scanning.

  When the pixel data is generated, the scanning microscope 100 determines whether the pixel data has been generated for all lines (step S3). Here, for example, if the number of pixels in the vertical direction is 768, the computer 20 determines whether or not pixel data has been generated for all 768 lines. If pixel data is not generated for all lines, the scanning microscope 100 moves the scanning start position in the Y direction with the scanner 4b (step S4), and then performs oversampling while scanning in the X direction. The generation of pixel data is repeated (step S1 and step S2). By performing these processes on all lines, pixel data of all areas within the scanning range of the two-dimensional scanning mechanism 4 is generated. Hereinafter, a set of pixel data of all regions within the scanning range of the two-dimensional scanning mechanism 4 is referred to as scanned image data.

  When pixel data is generated for all lines, the scanning microscope 100 determines whether pixel data has been generated for all heights (step S5). Here, for example, the computer 20 determines whether or not pixel data has been generated at all preset heights. The height is the distance in the Z direction from the upper surface of the stage 9 to the observation surface, and is specified based on the output result from the displacement meter 17, for example. If the pixel data is not generated at all the set heights, the scanning microscope 100 moves the scanning start position in the Z direction by the focus moving mechanism 18 (step S6), and then moves to all lines. On the other hand, oversampling performed while scanning in the X direction and generation of pixel data are repeated (step S1 to step S4). Thereby, scanned image data at each height is generated.

  When the pixel data is generated at all the heights, the scanning microscope 100 generates the height information of the sample S (Step S7) and ends the process. Here, based on a plurality of scanned image data, the computer 20 generates a luminance change curve (hereinafter referred to as an IZ curve) for each pixel region. Then, the height information of the sample S is generated by specifying the height of the pixel region based on the IZ curve. For example, as shown in FIG. 6, the height Z0 indicating the maximum luminance value I0 of the sampled heights may be specified as the height of the pixel region, and the shape of the IZ curve is calculated. Then, the height at which the luminance value becomes maximum on the IZ curve may be specified as the height of the pixel region. In FIG. 6, black circles indicate the sampling results. Furthermore, the computer 20 may generate omnifocal image data in which the entire scanning range is in focus based on pixel data having a height specified for each pixel region.

  In the scanning microscope 100 according to the present embodiment, each pixel data is generated from a plurality of digital signals by oversampling the analog signal output from the photodetector 13. For this reason, it is possible to generate highly reliable pixel data in which the ratio of the noise component is suppressed without excessively complicating the configuration of the microscope body 10. In addition, even though a resonant scanner is used, pixel data can be generated from digital signals acquired at sampling positions that are spatially arranged at equal intervals, so that higher reliability can be realized. . Therefore, by generating the height information based on the pixel data generated by the scanning microscope 100, it is possible to reproduce a more accurate three-dimensional shape of the sample.

  In a conventional scanning microscope, since improvement in resolution cannot be expected even if sampling is performed at an interval equal to or less than the optical resolution, the sampling interval is usually designed to be about the optical resolution. However, regarding the S / N ratio, the S / N ratio can be improved as the number of samplings is increased. Therefore, in the scanning microscope 100, a sampling clock is generated so that the sampling position on the sample S moves at an interval narrower than the optical resolution of the scanning optical system, and the analog signal output from the photodetector is oversampled. It is desirable.

  In the scanning microscope 100, pixel data is generated based on a plurality of digital signals having a small time difference in sampling timing. For this reason, although pixel data is generated based on a plurality of digital signals acquired at different sampling positions, the influence of the sampling position difference and the time difference is negligible. In particular, when sampling is performed at intervals smaller than the optical resolution, the influence on reliability can be ignored. Therefore, the merits of generating highly reliable pixel data from a plurality of digital signals can be fully enjoyed.

  Finally, a clock generation circuit 15 that generates a sampling clock synchronized with the scanning speed of the scanner 4a will be described with reference to FIGS. FIG. 7 is a block diagram showing an example of the configuration of the clock generation circuit 15. FIG. 8 is a diagram showing the relationship between the sampling clock generated by the clock generation circuit 15 and the scanning position. 7 is merely an example of the configuration of the clock generation circuit 15, and the configuration of the clock generation circuit 15 is not limited to the configuration illustrated in FIG.

  The clock generation circuit 15 includes a phase comparator 51, a loop filter 52, a voltage controlled oscillator (hereinafter referred to as VCO) 53, a counter 54, a memory 55, a D / A converter 56, a VCO 57, a counter 58, and a phase comparison. A device 59 and a loop filter 60 are provided.

  The phase comparator 51 receives a scanning timing signal output from the scanning drive control circuit 14 and a timing signal output from the counter 54 (hereinafter referred to as a first timing signal). The first timing signal will be described later. The phase comparator 51 detects a phase difference between two input signals (scanning timing signal and first timing signal) and outputs a signal corresponding to the phase difference. For example, as the first timing signal is earlier than the scanning timing signal, a lower voltage signal is output, and as the first timing signal is later, a higher voltage signal is output. The signal output from the phase comparator 51 is input to the VCO 53 via the loop filter 52 that is a low-pass filter. The VCO 53 is a variable frequency oscillator and generates a clock having a frequency corresponding to an input signal (voltage). For example, a high frequency clock is generated as a high voltage is input, and a low frequency clock is generated as a low voltage is input. The counter 54 counts the clock from the VCO 53 and outputs a first timing signal to the phase comparator 51 each time it counts a preset number of times C1 (for example, 1000 times). The counter 54 also outputs the first timing signal to a phase comparator 59 described later.

  The scanning timing signal and the first timing signal are converged in the same period and in the same phase by a loop constituted by the phase comparator 51 to the counter 54. For this reason, in the convergence state, the same number of clocks as the number of times C1 are output from the VCO 53 at regular time intervals during one scanning cycle. That is, a clock with a constant frequency is output from the VCO 53.

  The memory 55 has at least as many addresses (from 0 to 999) as the number of times C1 set in the counter 54, and each address has a speed for reproducing the speed waveform (sine waveform) of the scanner 4a. Information is stored. For example, the speed information of the scanner 4a at the timing of (N-1) / C1 cycle is stored in the Nth address number. Each time the counter 54 counts, the D / A converter 56 reads speed information from the address of the memory 55 corresponding to the counter value and converts it into an analog signal. As a result, a voltage that reproduces the velocity waveform (sine waveform) of the scanner 4 a is output to the VCO 57. The VCO 57 is a variable frequency oscillator similar to the VCO 53, and generates a clock having a frequency corresponding to an input signal (voltage). Therefore, when the speed of the scanner 4a is high and the input voltage is high, a clock is output at a high frequency, and when the speed is low and the input voltage is low, a clock is output at a low frequency. The clock output from the VCO 57 is output to the A / D converter 16 as a sampling clock.

  The counter 58 counts the clock from the VCO 57 and outputs a second timing signal to the phase comparator 59 each time it counts a preset number of times C2 (for example, 2048 times). The phase comparator 59 detects the phase difference between the first timing signal output from the counter 54 and the second timing signal output from the counter 58 and outputs a signal corresponding to the phase difference. For example, as the second timing signal is earlier than the first timing signal, a lower voltage signal is output, and as the second timing signal is slower, a higher voltage signal is output. The signal output from the phase comparator 59 is input to the D / A converter 56 via the loop filter 60 that is a low-pass filter. The D / A converter 56 adjusts the magnitude of the analog signal according to the signal from the phase comparator 59 and outputs it.

  Since the first timing signal and the second timing signal converge in the same cycle and in the same phase by the loop composed of the counter 54 and the loop filter 60, the scanning timing signal and the second timing signal also have the same cycle and the same phase. Converge. As a result, in the convergence state, the VCO 57 outputs the same number of sampling clocks as the number of times C2 in one scanning cycle at a timing at which the scanning position moves at equal intervals. That is, the sampling clock synchronized with the scanning speed of the scanner 4a is output from the VCO 57.

  According to the clock generation circuit 15 configured as described above, by setting the number of times C2 set in the counter 58 to a number exceeding the number of pixels in the horizontal direction, sampling exceeding the number of pixels in the horizontal direction during one scanning cycle. The clock can be generated at a timing such that the scanning position moves at equal intervals. Then, even when a scanner that moves at non-constant speed such as a resonant scanner is used by the A / D converter 16 performing sampling in accordance with the sampling clock generated by the clock generation circuit 15, it is shown in FIG. As described above, sampling can be performed a plurality of times within one pixel region while moving the sampling positions at equal intervals.

  FIG. 9 is a diagram illustrating the relationship between the sampling clock generated by the clock generation circuit according to the present embodiment and the scanning position. The scanning microscope according to the present embodiment has the same configuration as that of the scanning microscope 100 except that a clock generation circuit that generates a sampling clock at a constant frequency is provided instead of the clock generation circuit 15. .

  In the scanning microscope according to the present embodiment, as shown in FIG. 9, the analog signal output from the photodetector 13 is oversampled, and the resulting number of digital signals exceeding the number of horizontal pixels is obtained. The same number (two in this case) of digital signals is selected for each pixel region, and pixel data corresponding to each pixel region is generated. The point that each pixel data is generated from a plurality of digital signals is the same as in the first embodiment. For this reason, also in the scanning microscope according to the present embodiment, similarly to the scanning microscope 100 according to the first embodiment, the reliability of the noise component is suppressed without excessively complicating the configuration of the microscope body 10. High pixel data can be generated. In addition, similar to the scanning microscope 100, it is possible to reproduce a more accurate three-dimensional shape of the sample by generating height information based on the generated pixel data. Further, since a general clock generation circuit can be used without requiring a complicated circuit configuration like the clock generation circuit 15, a scanning microscope can be easily configured.

  In general, an oscillator that generates a clock at a constant frequency can oscillate a clock at a higher frequency than an oscillator (for example, a VCO) that oscillates a clock at a non-constant frequency. For this reason, when the clock generation circuit according to this embodiment generates a sampling clock having a sufficiently high frequency, the sampling positions of the digital signal are not spatially arranged at equal intervals on the sample as shown in FIG. However, it is possible to select a plurality of digital signals acquired from a large number of digital signals at sampling positions that are spatially arranged at equal intervals. Therefore, according to this embodiment, it is possible to generate pixel data based on digital signals acquired at sampling positions arranged at equal intervals. In addition, even when there is no digital signal acquired at equally spaced sampling positions, a digital signal at an equally spaced position is calculated from a large number of digital signals by interpolation, and pixel data is calculated based on the calculated digital signal. It may be generated.

  The embodiments described above are specific examples for facilitating understanding of the invention, and the present invention is not limited to the embodiments described above. The scanning microscope and the pixel data generation method can be variously modified and changed within the scope of the present invention described in the claims.

  Although an example in which the scanning microscope detects reflected light has been shown, the light to be detected is not particularly limited. For example, any light generated due to illumination such as transmitted light, fluorescence, and evanescent light can be detected. Although the laser light source is illustrated, the light source is not limited to the laser light source. Moreover, although the example which uses a resonance scanner as a scanning means was shown, the scanning means may be a galvano scanner. Furthermore, although the example in which the scanning unit acts on both the illumination light and the detection light has been shown, the scanning unit may be disposed on at least one of the illumination optical path and the detection optical path. For example, the entire scanning range of the sample S may be illuminated at the same time, and light from each region of the sample S may be sequentially detected by a photodetector using scanning means arranged in the detection light path. In addition, each region of the sample S may be sequentially illuminated using a scanning unit arranged in the illumination optical path, and light from each region may be detected by a non-descan detector (NTD).

  Further, the scanning microscope may have a function of regenerating pixel data as necessary by recording the sampled digital signal. For example, when noise is seen in the displayed image, the pixel data may be regenerated by changing the combination of digital signals for generating the pixel data. Moreover, although the example which produces | generates pixel data with the computer 20 was shown, instead of producing | generating pixel data by software processing using the computer 20, pixel data is produced | generated by hardware processing using FPGA (Field Programmable Gate Array) etc. It may be generated.

DESCRIPTION OF SYMBOLS 1 Laser light source 2, 5 Mirror 3 Half mirror 4 Two-dimensional scanning mechanism 4a, 4b Scanner 6, 11 Lens 7 Revolver 8 Objective lens 9 Stage 10 Microscope main body 12 Confocal stop 13 Photo detector 14 Scan drive control circuit 15 Clock generation circuit 16 A / D converter 17 Displacement meter 18 Focus movement mechanism 19 Trajectory 20 Computer 21 Pixel data generation unit 22 Display data generation unit 30 Display device 40 Input devices 51 and 59 Phase comparators 52 and 60 Loop filters 53 and 57 VCO
54, 58 Counter 55 Memory 56 D / A converter 100 Scanning microscope S Sample

Claims (14)

A scanning optical system including scanning means for scanning the sample with light;
A photodetector that detects light from the sample scanned by the scanning means and outputs an analog signal;
Sampling means for oversampling the analog signal output from the photodetector and outputting a digital signal;
A scanning microscope comprising: pixel data generation means for generating pixel data corresponding to each region of the sample based on a plurality of digital signals output from the sampling means. The scanning microscope according to claim 1, further comprising:
A clock generating means for generating a sampling clock so that the sampling positions on the sample move at equal intervals;
The scanning means scans the sample at a non-constant speed,
The scanning microscope according to claim 1, wherein the sampling unit oversamples the analog signal in accordance with the sampling clock generated by the clock generation unit. The scanning microscope according to claim 2,
The scanning microscope characterized in that the clock generation means generates the sampling clock based on a signal indicating a scanning timing of the scanning means and velocity waveform information of the scanning means. The scanning microscope according to claim 1, further comprising:
A clock generating means for generating a sampling clock at a constant frequency;
The scanning means scans the sample at a non-constant speed,
The scanning microscope according to claim 1, wherein the sampling unit oversamples the analog signal in accordance with the sampling clock generated by the clock generation unit. The scanning microscope according to any one of claims 1 to 4,
The scanning microscope characterized in that the sampling means oversamples an integral value obtained by time-integrating the analog signal. The scanning microscope according to any one of claims 1 to 5,
The scanning data microscope is characterized in that the pixel data generating means generates each of a plurality of pixel data corresponding to different regions of the sample based on the same number of digital signals output from the sampling means. The scanning microscope according to any one of claims 1 to 6,
The pixel data generation unit is configured to generate the pixel data based on the plurality of digital signals so that a ratio of noise components included in the pixel data is smaller than a ratio of noise components included in each of the plurality of digital signals. A scanning microscope characterized by generating The scanning microscope according to claim 7,
The scanning data microscope characterized in that the pixel data generating means statistically processes the plurality of digital signals to generate the pixel data. The scanning microscope according to any one of claims 1 to 6,
The pixel data generation unit generates the pixel data based on the plurality of digital signals so that a dynamic range of the pixel data is larger than each dynamic range of the plurality of digital signals. Scanning microscope. The scanning microscope according to claim 9, wherein
The scanning data microscope characterized in that the pixel data generation means generates the pixel data by integrating the plurality of digital signals. The scanning microscope according to any one of claims 1 to 10,
The scanning microscope characterized in that the scanning means is a resonant scanner. The scanning microscope according to any one of claims 1 to 11,
The scanning data microscope is characterized in that the pixel data generation means generates one display pixel data from one or more of the pixel data. The scanning microscope according to any one of claims 1 to 12,
The sampling unit oversamples an analog signal output from the photodetector so that a sampling position on the sample moves at an interval narrower than an optical resolution of the scanning optical system. microscope. A pixel data generation method for a scanning microscope comprising a scanning means and a photodetector,
Detecting light from the sample scanned by the scanning means with the photodetector;
Oversampling the analog signal output from the photodetector,
A pixel data generation method, wherein pixel data corresponding to each region of the sample is generated based on a plurality of digital signals obtained by oversampling.