Chapter 51: Light source test (below)

　　 Everyone returned to the control room, Luo Yang sat in front of one of the computers and said:
　　"When measuring thin film samples like yours, X-rays must hit the edge of the silicon wafer at a nearly horizontal angle.
　　 It is necessary to ensure that during each test, exactly half of the X-rays are blocked by the silicon wafer, and the other half of the X-rays are irradiated on the surface of the sample and interact with the sample to produce diffraction signals, which are finally collected by the signal collector.
　　In order to prevent the signal collector from being directly irradiated by the rays, a lead coin must be placed in front of it to absorb most of the X-rays.
　　 Now let’s debug. "
　　 Luo Yang used the programming language to control the instruments in the test cabin and introduced:
　　 "The debugging process is just to tell you, if you don't understand, it won't affect your test.
　　 In the first step, we first move the sample stage in the vertical direction, that is, in the z direction, towards the direction of the ground, so that the sample does not block the X-ray at all.
　　 At this time, the signal intensity on the detector is almost constant, and it is also its maximum value. This extreme value needs to be recorded.
　　 The second step is to slowly raise the sample stage until the signal intensity on the detector begins to decrease, which indicates that the sample has begun to block the X-rays.
　　 The third step is to make the z-coordinate of the sample stage change linearly within a small range. During this period, scan the signal intensity to obtain a curve of the signal intensity changing with the z-coordinate.
　　 Find the corresponding z coordinate when the signal intensity is about half of the maximum intensity, and move the sample stage to this z coordinate.
　　 At this time, it corresponds to the state where half of the X-rays are blocked by the sample.
　　 In the fourth step, we need to calibrate the rotation angle of the sample stage, because we do not know whether the incident X-ray is completely parallel to the sample surface.
　　 Let the rotation angle θ of the sample stage change within a smaller angle range, during which the signal intensity is scanned, and the curve of the signal intensity changing with θ is obtained.
　　 Find the θ coordinate corresponding to the maximum signal intensity, and rotate the sample stage to this angle. At this time, the X-ray is directed parallel to the side of the sample.
　　 Manually set the rotation angle at this time to 0 degrees.
　　Because we have rotated the sample stage, the incident X-ray is no longer half blocked by the sample.
　　 Therefore, it is necessary to repeat the third and fourth steps.
　　 Until the highest value of the sample signal in the fourth step, the corresponding rotation angle is 0 degrees.
　　 As it is now, we have completed the debugging. "
　　 "After the debugging is completed, the incident angle can be set for testing. What is your incident angle in general?" Luo Yang asked Chen Wanqing.
　　 "0.12 degrees," Chen Wanqing said.
　　 Luo Yang typed a piece of code in the computer:
　　Umvthita0.12;
　　 press Enter, and then say:
　　" After setting, every time you change the sample, you should check whether the signal intensity on the detector is close to half of the maximum value.
　　 If the deviation is too large, it needs to be cut again, that is, repeat the third and fourth steps.
　　 After cutting the light, change the incident angle to 0.12 degrees. "
　　 "These steps of operations can be found in this user manual, there is a test registration form in it, remember to fill in." Luo Yang handed the manual to Chen Wanqing and said:
　　 "I left a phone number for you on it, call me if you have something to do, if you want to leave after the test in advance, just go to the master control to turn off the light, and then send me a text message.
After 　　, the testing software can be operated, so I don’t need to teach it again. "
　　 "No need to teach, I will use the software." Chen Wanqing said.
　　……
　　 After Luo Yang left, Chen Wanqing said happily: "This time the debugging is faster, and it only took more than an hour."
　　 "Yes, I feel that Luo Yang still knows the instrument well, he should be the teacher here," Xu Qiu glanced at the time and said, "It's almost 11 o'clock in the evening."
　　 "Then let's divide the work, one person is responsible for changing samples, and the other person is responsible for testing." Chen Wanqing said.
　　 "Let me change the sample, hand the physical work to me, let's test the installed sample No. 1 first." Xu Qiu said.
　　 Chen Wanqing nodded and started operating the software, setting the sample name, file storage location, and exposure time.
　　"When testing a new sample, it is usually necessary to test the exposure data for 10 seconds first to see if there are any problems with the obtained image.
　　 If the surface of the tested sample is not flat, it may cause the signal intensity in some areas of the image to be too high, or even exceed the detection limit of the instrument. In this case, you need to go to the test chamber to adjust the position of the sample.
　　 If there are no abnormal points in the image, you can adjust the exposure time to 100 seconds, 200 seconds, 300 seconds or other times.
　　 As long as the highest signal intensity does not exceed 50,000, the higher the exposure time, the better the image quality. "Chen Wanqing said.
　　 Sample No. 1, after 10 seconds of exposure test, no abnormal points appeared, and the highest signal intensity was about 1000.
　　 Because 1000(300/10)=30000, which is less than 50,000, Chen Wanqing directly changed the exposure time to 300 seconds and tested again.
　　……
　　 Sample No. 1, the test is completed.
　　 No. 2 sample, the test is completed.
　　 Sample No. 3, the test is completed.
　　……
　　 Sample No. 10 had abnormal spots. Xu Qiu reopened the hatch to adjust the position of the samples and re-tested. The abnormal spots disappeared. The test is complete.
　　……
　　 No. 17 sample, the abnormal point appeared again. After Xu Qiu adjusted the position of the sample 4 times, the abnormal point still did not disappear~EbookFREE.me~ I had to give up testing the sample.
　　……
　　 Sample No. 33, Xu Qiu was a little anxious when closing the door, stepped on the pressure sensor in front of the door, and the door slowly opened, so he had to close the door again.
　　……
　　 No. 43 sample, the test is completed.
　　 It was already three thirty in the morning.
　　 Xu Qiu has repeated the opening and closing operations more than 50 times, and he finally knows why this equipment costing more than one billion yuan does not require professionals to keep an eye on it.
　　Because they are all fool-like operations, although the operation steps are cumbersome, it is also proficient to repeat dozens of times.
　　 Unless the instrument is deliberately destroyed, it is difficult to cause damage to the equipment.
　　 Running around is quite tiring, mainly because every time I press search 1, I have to bend twice, and my ears are always accompanied by piercing alarms.
　　 Fortunately, the exposure time of each test is relatively long, during which you can sit and rest for a while.
　　 At this time, both of them were a little sleepy. They ate a little bit and gritted their teeth to continue the test.
　　 "I'll change the sample for you. Come and rest for a while." Chen Wanqing said.
　　 "Sister, would you change the sample?" Xu Qiu asked.
　　 "Of course, I did the test by myself before, and I did all the sample changes and tests." Chen Wanqing said.
　　 "It's too hard for one person, aren't the others coming?" Xu Qiu said.
　　 "They don't have samples, and it's not good to pull them over to help with the test. The main reason is that they were tested during the day two times before, so it was actually fine." Chen Wanqing said.
　　 "Okay, go ahead, senior sister." Xu Qiu sat in front of the test computer.
　　 "Hmm," Chen Wanqing nodded and said, "Mainly I want to move, or I will fall asleep after sitting all the time."