This standard specifies the measurement method of the extinction ratio along the optical axis of lithium niobate, potassium dihydrogen phosphate and potassium dideuterium phosphate crystals using a light wave with a wavelength of 632.8nm. This standard is applicable to the measurement of an extinction ratio of 100000:1. GB 11297.12-1989 Measurement method of extinction ratio of electro-optical crystals lithium niobate, potassium dihydrogen phosphate and potassium dideuterium phosphate GB11297.12-1989 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for extinctlon ratio of LN,KDP and KD'P electrooptic crystalGB 11297. 12-: 89
This standard specifies the method for measuring the extinction ratio along the optical axis of LN,KDP and KD'P electrooptic crystal using a light wave with a wavelength of 632.8 nm.
This method is applicable to measuring the extinction ratio of 100 000:1. 1 Terminology
The definition symbols of the terms used in this standard conform to GB11293 "Terms of Solid Laser Materials". 2 Measurement Principle
When a beam of light with a wavelength of 632.8nm passes through a crystal placed in an orthogonal polarization system along the optical axis of the crystal to be measured, the crystal is rotated with the optical axis as the axis, and the transmitted light intensity is taken as the minimum value "call". Then the polarizer is rotated to parallel the polarization system, and the maximum value of the transmitted light intensity Imx is measured. The ratio of the light intensity Ix to In is defined as the extinction ratio E,·R of the crystal to be measured. As shown in formula (1): E..R
3 Measuring device and measuring conditions
The extinction ratio measuring device consists of the components and instruments shown in Figure 1. 1ma
1—Nitrogen pump laser light source; 2—Beam expansion collimator; 3—Adjustable light bar: 4—Polarizer: 5—Measured crystal; 6—Analyzer 17—Photoelectric receiving element; 8—Display instrument 3.1 Ammonia laser light source: Single transverse mode, the power fluctuation of the light source should be less than or equal to 1% and the divergence should be less than or equal to 3mrad. 3.2 Polarizer and analyzer: The polarization degree should be greater than or equal to 99. 9%, the angle accuracy of the polarizer is 5'. 3.3 Photoelectric receiving element: silicon photocell or other photoelectric receiving element. The element is required to work in the linear region. 3.4 X-ray instrument: use a 0.1-level microvoltmeter or microammeter, or other instruments with equivalent accuracy. Approved by the Ministry of Machinery and Electronics Industry of the People's Republic of China on October 9, 1988
Implementation on January 1, 1990
3.5 Stage: with a fine-tuning mechanism for rotation angle. CB11297.12—89
3. 6 The temperature coefficient of the refractive index of the object under test will affect the test accuracy of the extinction ratio. It is stipulated that the change in the measurement environment temperature should be less than ±1°C. 3.7 The size of the aperture greatly affects the measurement data. It is stipulated that the aperture of the measurement beam is 1mm. 3.8 The orientation and optical processing accuracy of the object under test will affect the measurement accuracy of the extinction ratio. It is stipulated that: 3.8.1 The deviation between the verticality of the optical axis of the crystal under test and the light-transmitting surface should be less than 2. 3.8.2 The non-parallelism of the two end faces of the object under test should be less than 30\3.8.3 The flatness of the two end faces of the crystal under test should be better than one-quarter aperture3.8.4 The finish of the two end faces of the object under test should be better than BII grade (GB 1185 in B level). Measurement steps www.bzxz.net
4.1 Turn on the nitrogen laser light source. To ensure the stability of the measurement, preheat for 15~-30min. 4.2 Before each measurement, the system extinction ratio must be calibrated to ensure the accuracy of the measurement system. 4.2.1 Without placing the measured crystal in the system, adjust the system to an orthogonal polarization system and measure 1min; then adjust it to a parallel polarization system and measure 1max. The system extinction ratio can be obtained by using formula (1,
4.2.2 If the extinction ratio of the measurement system is lower than 100000:1, it is necessary to adjust and check each component to make the measurement system meet the requirements of the system extinction ratio. 4.3 Clean the light of the measured crystal.
4.4 Place the measured object on the fixture of the stage, and avoid any factors that cause stress on the crystal. 4.5 Place the measured crystal in the light group for 30 minutes to make the crystal and the ambient temperature the same. 4.6 Adjust each component to make it coaxial with the measuring beam, until the crystal optical axis is coaxial with the beam. 4.7 Rotate the crystal with the optical axis as the axis, and measure the minimum value of the transmitted light intensity in the orthogonal polarization system of the crystal, 1 yuan i. 4.8 Rotate the polarizer to make the measuring system a parallel polarization system, and measure the maximum value of the transmitted light intensity, Inx4.9 Substitute 1, α, and 1min into formula (1) to calculate the extinction ratio of the measured crystal. 5
Measurement accuracy
The measurement accuracy of this method is ±5%
6 Contents of measurement report
6.1 Name of operator.
6.2 Test period.
6.3 Number and size of the measured crystal.
6.4 Measure the ambient temperature.
6.5 Measure the beam diameter.
6.6 Measure the extinction ratio of the system.
6.7 Extinction ratio of the measured crystal.
Additional remarks:
This standard was drafted by the Tenth Research Institute of the Ministry of Machinery and Electronics Industry and the Crystal Institute of Shandong University. The main drafters of this standard are Zhang Peihe and Shao Zongshu.
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