Chapter 1623 Breaking through Abe’s limit!

“Academician Chang, what is this…?” Luan Wenjie looked around, somewhat puzzled.

Compared with the lithography machine test next to it, which is related to the lifeblood of National Semiconductor, the equipment here seems too "ordinary".

"A purely optical...principle verification experiment." Chang Haonan said succinctly, his eyes fixed on Li Yabo. "We have been preparing for almost half a year, and only recently have the conditions for testing."

"Pure optics? What to verify?" Luan Wenjie was even more confused.

"You'll know soon." Chang Haonan still kept it a secret, motioning Luan Wenjie to watch patiently, his eyes also directed at Li Yabo's operation.

Li Yabo finally confirmed the coaxiality of all optical components, and then very carefully inserted a palm-sized metal plate covered with extremely fine black and white stripes into a special target holder, and fine-tuned the position and angle.

Then he walked to the control computer and tapped his fingers quickly on the keyboard.

hum...

With a slight startup sound, the light source at one end of the platform was lit.

Instantly, a bright red laser beam shot out, and after beam expansion and collimation, it turned into a parallel red light with a diameter of about several millimeters, shooting into the black light shield in the middle.

And when the light comes out from the other end, it has a slight, imperceptible blur.

Finally, this beam of light is projected onto a precision imaging screen several meters away, forming a light spot with soft boundaries.

"Red light?" Luan Wenjie exclaimed in astonishment, "Or is it visible light?"

In his opinion, to break through the limits, one should use ultraviolet light or even extreme ultraviolet light with shorter wavelengths.

Chang Haonan seemed to have anticipated his question and explained calmly:

"What we want to test is a result that is theoretically 'impossible' to achieve with traditional lenses... If we use light with a wavelength that is too short, then... the accuracy and noise requirements of the test system itself will be very high, and there is a high probability that no valid results can be measured."

As soon as he finished speaking, Li Yabo, who had been staring at the computer screen, raised his head:

"found it."

There was not much emotion on his face, but his voice was trembling:

"The image is clear! I found the image result of the target!"

"quick!"

Chang Haonan immediately took a few steps forward and took over from Li Yabo and sat in front of the monitor.

Luan Wenjie couldn't hold back his curiosity and quickly moved over.

What is displayed on the screen is not some complicated circuit, but a series of vertical stripes with alternating light and dark colors and equal width and spacing.

The edges of the stripes are sharp and the contrast is very high.

He quickly searched the knowledge in his mind, but couldn't think of an answer that fit the current scenario.

But looking at the posture of the teacher and student in front of him, he could already sense that the thing in front of him might not be ordinary.

Fortunately, Chang Haonan did not let the other party's doubts last too long.

"This is part of the resolution test target." He pointed to the vertical stripes on the screen and explained, "According to the Rayleigh criterion of optical imaging, when using visible red light with a wavelength of λ=632.8nm, the theoretical resolution limit δ of a traditional lens is about 0.61λ/NA...Converted to our system, it is about 316nm."

He pointed to a set of numbers next to the clearest set of stripes on the screen:

"Look here, the line width of the 10th element of the 5th group is 308nm... That is to say, for a normal lens, the pattern below the 632.8th element of the 10th group on the target should not be clearly visible at a wavelength of 5nm."

Chang Haonan paused deliberately when he said this:

"but……"

Instead of continuing to speak, he moved the mouse and searched quickly on the screen.

Soon, the cursor stopped at an area on the left side of the screen, where a pattern consisting of three vertical bright lines was clearly displayed, with black lines of equal width between the bright lines.

The label of this pattern on the screen is "Group 10, Element 5"!

"Ok?"

Luan Wenjie screamed in surprise and leaned forward involuntarily, almost sticking to the screen.

The Rayleigh criterion is the basis of physics, and he has just understood the meaning of this test.

308nm, which has exceeded, or at least is close to, the resolution limit corresponding to the 632.8nm wavelength

However, the three bright lines in front of my eyes are so clear and sharp, with smooth edges, without the slightest blur or dispersion.

It doesn't seem like we are approaching the theoretical limit at all, but rather like we are distinguishing an object that is much larger than the limit!

Chang Haonan still maintained the calm expression of someone in control of everything on his face, and did not immediately respond to Luan Wenjie's shock.

He simply moved the mouse again, controlling the imaging area on the screen to move downward.

The scene switches to the area marked "Group 10, Element 6".

The line pattern here is much finer.

However, the three bright lines in the figure are still clearly visible.

Compared with the 9-5, its sharpness has almost no visible attenuation!

"10 groups of 6 elements, corresponding to a resolution of 274nm!"

Li Yabo next to him reported the data at the right time.

Luan Wenjie's eyes were wide open, and he was completely shocked by the scene before him.

274nm!

The results just now may also be explained by errors.

But this time, it has clearly broken through the theoretical diffraction limit of 632.8nm red light.

This completely subverts common sense in optics!

Chang Haonan remained silent, his fingers steadily controlling the mouse. The picture on the screen continued to move downwards:

Group 11, Element 1 (corresponding resolution of about 244nm) – Clear!

Group 11, Element 2 (about 218nm)–Clear!

Group 11, Element 3 (about 194nm)–Clear!

……

Luan Wenjie's heartbeat quickened with every scene change, and his breathing became rapid.

Every time a clear image appears, it ruthlessly impacts and shatters the cornerstone of centuries-old optical theory!

The screen switches again:

Group 11, Element 4–The three bright lines remain resolvable.

Although the contrast is lower than the previous groups and the bright lines seem to be slightly thinner, they are still clearly juxtaposed and the black seam in the middle is clearly present!

This has already surpassed the diffraction limit by quite a distance!

Luan Wenjie felt that his emotions seemed to be aroused. He stared at the screen and clenched his fists unconsciously.

Chang Haonan clicked again.

The scene switches to Group 11, Element 5.

This time, the scene on the screen finally changed.

The three bright lines that should have been clear and independent now looked like ink soaked in water, with blurred edges, sticking and merging together, forming a diffuse light spot with unclear boundaries and slightly higher brightness, and any independent line structure could no longer be distinguished!

"I can't see clearly!" Luan Wenjie and Li Yabo shouted in unison almost at the same time!

After blurting out the words, the former realized that he seemed to have lost his composure.

But fortunately, there was no outsider here, so he quickly stared at the screen in front of him again.

"This pattern is Group 11, Element 5!"

He accurately called out the number of the target element that had just become blurred, his voice a little distorted due to excitement.

Chang Haonan nodded, his eyes fixed on the last clear pattern on the screen: "Yes, so the last one that can be clearly distinguished is 11 groups of 4 elements." He then turned to Li Yabo, "Yabo, target board instructions."

Li Yabo immediately opened the instruction manual and placed it in front of the keyboard.

This manual records in detail the precise line width and resolution values corresponding to each group and each element on the USAF 1951 resolution target.

Because the elements in group 11 are extremely tiny and rarely used in routine tests, even Chang Haonan cannot remember their specific values immediately.

The laboratory suddenly became quiet, with only the heavy breathing of a few people remaining.

Everyone's eyes were focused on Chang Haonan's fingertips moving along the form.

I quickly found group 11 along the directory, then moved down along the element number, and finally stopped steadily under a number:

"Group 11, Element 4... Resolution: 0.173mm... 173nm."

173 nanometers!

This number was like a thunder, exploding in the small laboratory!

Chang Haonan raised his head and glanced at Luan Wenjie, whose face was filled with shock, and Li Yabo, whose cheeks were flushed with excitement. His voice was calm, but it contained enough power to rewrite the textbooks:

"The theoretical diffraction-limited resolution under 632.8nm wavelength red light is about 316nm, calculated by the loosest Rayleigh criterion. According to the stricter Sparrow criterion or actual engineering experience, it is generally considered to be around 350nm."

He paused, and every word he said was powerful:

"The final clearly discernible 11 groups of four elements we observed had a resolution of 4nm."

"Even allowing for the possibility of slight errors in the test, this result clearly shows that—"

Chang Haonan's voice suddenly rose, with a penetrating force like a declaration:

"We have successfully broken through the Abbe diffraction limit of traditional optical imaging systems!"