CN209878133U - Calibration device for focal spot dynamic range by schlieren method - Google Patents
Calibration device for focal spot dynamic range by schlieren method Download PDFInfo
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Abstract
The utility model belongs to focal spot dynamic range marks the field, relates to a "schlieren method" focal spot dynamic range's calibration device, can accomplish the dynamic range of high power laser far field focal spot and mark. The calibration device comprises a laser light source, a collimating objective lens and a one-dimensional sinusoidal phase grating which are sequentially arranged along an emergent light path of the laser light source; the collimating objective expands the laser beam output by the laser source into a beam with a diameter ofThe light spot of (a); one-dimensional sine phase gratingTo the diameter ofThe light spots are modulated to generate a series of light spots with different diffraction orders; at least one diffraction order light spot can be found out in a series of light spots with different diffraction orders, and the ratio of the peak energy of the diffraction order light spot to the peak energy of the 0 diffraction order light spot is less than or equal to 1:104. A series of light spots with different diffraction orders are injected into a striae method far-field focal spot diagnosis system, and enter a side lobe measurement light path and a main lobe measurement light path respectively through a light splitting module in the diagnosis system to calibrate the dynamic range of the diagnosis system.
Description
Technical Field
The utility model belongs to focal spot dynamic range marks the field, relates to a "schlieren method" far field focal spot dynamic range's calibration device, can accomplish the dynamic range of high power laser far field focal spot and mark.
Background
The distribution of the high-power laser far-field focal spots is always the most concerned laser parameter index of an ICF experiment and the key performance index of a driver, and is the core index of a huge precise diagnosis system specially established by laser fusion devices of various countries.
The dynamic range of the high-power laser far-field focal spot is very high and reaches 104Above, at this time, the focal spot in this dynamic range cannot be directly obtained by the single CCD, so various methods for measuring the high dynamic range of the far-field focal spot have appeared, such as: array camera methods, schlieren methods, etc.
The array camera method only appears in the initial stage of far-field focal spot high dynamic range measurement, and the measured focal spot is distorted due to excessive additional aberration introduced by the measurement method, so that the focal spot morphology is seriously distorted, and the subsequent stage is replaced by a schlieren method.
The schlieren method is a domestic main method for measuring the high dynamic range of far-field focal spots at present, and is based on the principle that incident laser is divided into two paths for measuring the focal spots, one path is used for measuring the central main lobe part of the focal spots, the other path is used for blocking the central main lobe part of the focal spots and measuring the peripheral side lobe part of the focal spots, and finally, the obtained main lobe and side lobe images are reconstructed, so that a complete far-field focal spot image is obtained.
Although the reconstructed focal spot image is obtained by the schlieren method, the focal spot dynamic range measuring capability of the dual-optical-path split focal spot diagnostic system is unknown, so that the reliability of the measured data is not high.
SUMMERY OF THE UTILITY MODEL
The utility model provides a calibration device and method of "schlieren method" focal spot dynamic range can accomplish 104 and above focal spot dynamic range and mark.
The technical solution of the utility model is to provide a calibration device of "schlieren method" focal spot dynamic range, its special character lies in: the laser phase grating comprises a laser light source, a collimating objective lens and a one-dimensional sinusoidal phase grating, wherein the collimating objective lens and the one-dimensional sinusoidal phase grating are sequentially arranged along an emergent light path of the laser light source;
the collimating objective expands the laser beam output by the laser source into a beam with a diameter ofThe light spot of (a); the one-dimensional sine phase grating pair has the diameter ofThe light spots are modulated to generate a series of light spots with different diffraction orders; at least one diffraction order light spot can be found out in a series of light spots with different diffraction orders, and the ratio of the peak energy of the diffraction order light spot to the peak energy of the 0 diffraction order light spot is less than or equal to 1:104. Injecting a series of light spots with different diffraction orders into a striae shadow far-field focal spot diagnosis system, and respectively entering a side lobe measurement light path and a main lobe measurement light path in the diagnosis system through a light splitting module to performDynamic range calibration of the diagnostic system.
Further, the laser light source is a fiber laser or a free-output laser that can be coupled to the focus of the collimator objective.
Further, the laser source emits plane waves with the same wavelength as the calibrated system.
Further, during calibration, the calibration device is coupled to a focal spot diagnosis light path of a schlieren method, and the specific coupling position is the output of the one-dimensional sine phase grating and the output part of a focal spot diagnosis system of the schlieren method.
The utility model has the advantages that:
1. the utility model discloses utilize calibration device to mark "schlieren method" diagnostic system, give accurate credible focal spot dynamic range data, assess for large-scale high power laser device's far field focal spot and provide credible voucher.
2. The utility model discloses the light spot peak energy of the different diffraction orders of one-dimensional sinusoidal phase grating calibrates among the calibration device to the scientific grade CCD that utilizes linear dynamic range has been markd, guarantees to calibrate under calibration device self dynamic range's the prerequisite to "schlieren method" diagnostic system, further improves the accurate credibility that diagnostic system acquireed focal spot dynamic range data.
Drawings
Fig. 1 is a schematic diagram of the calibration device and the calibration light path of the present invention;
FIG. 2 is a schematic diagram of the intensity distribution of the diffraction spots of the present invention;
FIG. 3 is a schematic diagram of the optical path for calibrating the spot energy of the one-dimensional sinusoidal phase grating with different diffraction orders by using the scientific CCD;
fig. 4 is a focal spot reconstruction schematic diagram of the present invention;
the reference numbers in the figures are: 1-a calibration device, 11-a laser light source, 12-a collimating objective and 13-a one-dimensional sine phase grating;
2-a system to be calibrated, 21-a first spectroscope, 22-a second spectroscope, 23-a first far-field converging lens group, 24-a far-field amplifying lens group and 25-an attenuation sheet;
3-scaling system, 31-second far-field converging lens group, 32-CCD.
Detailed Description
The invention is further described with reference to the following drawings and specific embodiments.
The dynamic range requirement of the high-power laser far-field focal spot is more than 1041, the high dynamic range of the far-field focal spot is mainly measured by a dual-optical-path light splitting 'schlieren' method at present in China. Although a reconstructed focal spot image is obtained by the schlieren method, the measurement capability of the focal spot dynamic range of the dual-optical-path light-splitting focal spot diagnostic system is unknown, and the measurement capability of the focal spot dynamic range of the diagnostic system can be obtained after calibration. The utility model provides a calibration device and method of "schlieren method" focal spot dynamic range can accomplish 104And the above focal spot dynamic range calibration.
The calibration principle is as follows:
1) establishing a dynamic range of 10 or more41 (standard source) and calibrating the calibration device to ensure that the dynamic range of the calibration device is more than or equal to 104:1；
2) The calibration device is used as a light source for calibrating the 'schlieren method' diagnosis system, and the light source enters the diagnosis system, respectively enters a 'main lobe' measuring light path and a 'side lobe' measuring light path, and simultaneously obtains 'main lobe' light spots and 'side lobe' light spots;
3) reconstructing the 'main lobe' light spot and 'side lobe' light spot of the calibration device obtained in the diagnosis system to obtain a diffraction order focal spot image of the calibration device, and judging whether the dynamic ranges of the 0-order diffraction spot and the +/-4-order diffraction spot are more than or equal to 104:1。
The specific measurement principle is discussed in detail as follows:
the utility model provides a focal spot dynamic range calibration method based on sinusoidal phase grating modulation. Incident plane waves are modulated by the one-dimensional sinusoidal phase grating and then are focused by the far-field converging mirror group, a series of light spots with different energy and distributed diffraction orders are generated at the focal point, and the peak energy of the diffraction spots is reduced along with the increase of the diffraction orders. In a series of differencesIn the diffraction order light spots, specific diffraction order light spots can be found, and the ratio of the peak energy of the diffraction order light spots to the peak energy of the 0-order diffraction light spots is less than 1:104Therefore, the method can be used for calibrating the focal spot measurement dynamic range of the schlieren method.
The calibration light path is shown in fig. 1, and the calibration device 1 is composed of a laser light source 11, a collimating objective 12 and a one-dimensional sinusoidal phase grating 13; the laser light source 11 in this embodiment is a fiber laser or a free-output laser that can be coupled to the focus of a collimator objective. The system 2 to be calibrated is a striae method far-field focal spot diagnosis system. The collimator objective 12 expands the laser beam output from the laser source 11 into a beam with a diameter ofThe light spots are modulated by the one-dimensional sinusoidal phase grating 13 and then injected into a far-field focal spot diagnosis system of a schlieren method, and the light spots of different diffraction orders respectively enter a side lobe measurement light path and a main lobe measurement light path through a first spectroscope 21 and a second spectroscope 22 in the diagnosis system to calibrate the dynamic range of the diagnosis system.
13 calibers of one-dimensional sine phase gratingThe phase distribution period is d, the focal length of the first far-field focusing lens group 23 in the diagnostic system is f, and the distribution diagram of the diffraction spot intensity at the focal point is shown in fig. 2. Assuming that the peak energy of the + -3 th diffraction order spot is less than or equal to 1, the peak energy of the + -2 nd diffraction order spot is about 100 (or other suitable value), the peak energy of the + -1 st diffraction order spot is about 1700 (or other suitable value), and the peak energy of the 0 th diffraction order spot is 10000; the ratio of the peak energy of the 0-order diffraction light spot to the +/-3-order diffraction light spot is more than or equal to 104:1。
The present embodiment realizes calibration through the following processes:
1. calibrating the dynamic range of the calibrating device;
firstly, the scientific CCD32 with a calibrated linear dynamic range is used for calibrating the energy of light spots of different diffraction orders of the one-dimensional sinusoidal phase grating 13 to obtain light of each diffraction orderRelative scale relationship between spot peak energies (to ensure that the ratio of peak energies of 0-order diffraction and + -3-order diffraction is ≧ 1041) the principle of the calibration light path is shown as 3.
The calibration process is as follows:
1.1, building a calibration light path as shown in figure 3;
1.2, adjusting the output intensity of the laser light source, recording the output intensity as D1, and recording a 0-order diffraction light spot image and the peak intensity of the 0-order diffraction light spot as P through a CCD;
1.3, enhancing the output intensity of a laser light source, recording the output intensity as D2, recording a +/-m-order diffraction spot image and +/-m-order diffraction spot peak intensity (at the moment, a zero-order diffraction spot and a +/-1-order diffraction spot need to be blocked so as to prevent strong light from damaging the CCD) by using the CCD, and recording as V;
1.4, removing background noise from the zero-order diffraction spot image, amplifying the intensity by D2/D1 times, removing the background noise from the +/-m-order diffraction spot image, and splicing into a complete image. And calculating the ratio of the peak gray scale of the 0-level diffraction light spot to the peak gray scale of the +/-m-level diffraction light spot in the spliced complete image, namely the dynamic range which can be reached by the calibration light path, wherein m is 3 in the embodiment.
2. Calibrating a focal spot diagnosis system by using a calibration device;
as shown in fig. 1, after laser light of the calibration device enters the focal spot diagnostic system, a dynamic measurement range of the diagnostic system is calibrated.
The calibration steps of the diagnostic system are as follows:
1) coupling a calibration device into a focal spot diagnosis light path, and completing the measurement of diffraction spots from 0 order to +/-2 orders through a 'main lobe' measurement light path (the energy multiplying power of the diffraction spots from 0 order to +/-2 orders is more than or equal to 100 times); the main lobe light spots are not necessarily diffraction light spots of 0 order to +/-2 orders, and the light spots in the front order are selected according to the order from large to small of the peak energy of the light spots.
2) The side lobe measuring light path blocks 0-order and +/-1-order diffraction light spots by using a shadow mask to complete +/-2-order and +/-3-order diffraction light spot measurement (the energy multiplying power of +/-2-order and +/-3-order diffraction light spots is more than or equal to 100 times); similarly, the side lobe light spots are not necessarily diffraction light spots of +/-2 th order and +/-3 rd order, and the light spots in the later order are selected according to the sequence from large to small of the peak energy of the light spots. It should be noted that the main-lobe spot and the side-lobe spot must be selected continuously, and an overlapping spot is required between the two spots.
3) And performing energy normalization on the measured main-lobe light spots and side-lobe light spots to obtain a reconstructed image, as shown in fig. 4.
Comparing the energy extreme values of the 0-order diffraction spots with the attenuated 3-order diffraction spots in the reconstructed image to obtain whether the dynamic measurement range of the focal spot diagnosis system of the schlieren method meets 1041, the requirements.
The utility model discloses a to the demarcation of "schlieren method" diagnostic system laser far field focal spot dynamic range, can give accurate, credible data of focal spot dynamic range, assess for large-scale high power laser device's far field focal spot and provide credible voucher.
Claims (4)
1. The utility model provides a calibration device of "schlieren method" focal spot dynamic range which characterized in that: comprises a laser light source (11), and a collimating objective (12) and a one-dimensional sinusoidal phase grating (13) which are sequentially arranged along an emergent light path of the laser light source (11);
the collimating objective lens (12) expands the laser beam output by the laser source (11) into a beam with a diameter ofThe light spot of (a); the one-dimensional sine phase grating (13) has a diameter ofThe light spots are modulated to generate a series of light spots with different diffraction orders;
at least one diffraction order light spot can be found out in a series of light spots with different diffraction orders, and the ratio of the peak energy of the diffraction order light spot to the peak energy of the 0 diffraction order light spot is less than or equal to 1:104。
2. The apparatus for calibrating the dynamic range of focal spot according to claim 1, wherein: the laser light source (11) is a fiber laser or a free-output laser that can be coupled to the focus of a collimator objective.
3. The apparatus for calibrating the dynamic range of a focal spot according to claim 2, wherein: the plane wave emitted by the laser source (11) has the same wavelength as the calibrated system.
4. The apparatus for calibrating the dynamic range of a focal spot according to claim 2, wherein: the output of the one-dimensional sinusoidal phase grating (13) is used for coupling with the input of a 'schlieren' focal spot diagnostic system.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110044475A (en) * | 2019-04-03 | 2019-07-23 | 中国科学院西安光学精密机械研究所 | A kind of caliberating device and method of schlieren method focal spot dynamic range |
| CN111208603A (en) * | 2020-01-21 | 2020-05-29 | 武汉理工大学 | Device and method for on-line writing grating with high side lobe suppression ratio |
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2019
- 2019-04-03 CN CN201920450431.6U patent/CN209878133U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110044475A (en) * | 2019-04-03 | 2019-07-23 | 中国科学院西安光学精密机械研究所 | A kind of caliberating device and method of schlieren method focal spot dynamic range |
| CN110044475B (en) * | 2019-04-03 | 2023-05-26 | 中国科学院西安光学精密机械研究所 | Calibration device and method for dynamic range of focal spot by using schlieren method |
| CN111208603A (en) * | 2020-01-21 | 2020-05-29 | 武汉理工大学 | Device and method for on-line writing grating with high side lobe suppression ratio |
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