I started with a ship full of max-level veterans, and I'm just a complete noob.

That evening, Jiang Ming brought the graph paper he had drawn during the day back to his dormitory, spread it out, and re-traced it into the outline of the temporary X-ray orientation device.

The 3.8-degree crystal orientation deviation was broken down into five conditions: tube source, power supply, shielding, exposure, and film interpretation. He checked the existing resources of 502 item by item, and finally reserved the high voltage source and film interpretation columns as key supplements.

The principle of the back-reflection Laue method can be derived from the crystal diffraction equation. However, to truly apply it to germanium wafer cutting, it is also necessary to master spot indexing, geometric correction, and exposure conditions. In particular, the interpretation of the principal axes of the crystal lattice is crucial; a difference of even half a degree renders all the precision of the cutting fixture meaningless.

Jiang Ming pressed the outline drawing against the corner of the table, closed the curtains, and pressed his fingertips against the dark gold pages of the Tongtian Record.

He continued to trace the European academic lineage initiated by the von Kármán node, moving from the Department of Physics at the University of Göttingen to the chair of solid-state physics, mineralogy and crystallography.

The intertwined academic lineages ultimately come to rest under the name of a German crystallographer who died in 1952.

The dark gold lettering lists this person's research experience: in his early years, he worked on the optical axis cutting of calcite and quartz for a long time, and in his later years, he organized the X-ray Laue method into a directional process in crystal production.

As the nodes unfolded, the dormitory walls were bathed in dark golden light, and the outline of an old laboratory appeared before Jiang Ming.

On the wooden shelf were calcite samples, a brass goniometer, and rows of Laue films. A scholar with gray hair was leaning over the lamp, examining the spots with a magnifying glass.

Time seemed to stand still the moment Jiang Ming opened his notebook; the desktop light, the shadows of the trees outside the window, and the ripples in the enamel mug all froze.

The crystallographer first examined the shape of the fifth furnace crystal column and the readings of the eight polarizers, and then asked Jiang Ming to redraw the correspondence between the position of the crystal curvature and the device dispersion.

"Polarization can only help you confirm changes in direction. The diamond cubic structure of germanium needs to rely on diffraction spot indexing to keep the spindle error within the range required for industrial cutting."

He pulled a back-reflection film from the wooden frame and pointed out the central entrance aperture, sample position, and spot symmetry axis to Jiang Ming one by one.

An X-ray beam passes through the center of the film and shines on the surface of a single crystal. The family of crystal planes that satisfy the Bragg condition reflects the rays back, forming a combination of spots on the film determined by the crystal lattice structure.

The symmetry of a germanium crystal changes depending on the direction of its principal axis. The 1-1-1 direction exhibits triple rotational symmetry, while the 1-0-0 direction exhibits quadruple rotational symmetry.

By measuring the distance and orientation of the spot relative to the center of the film, and combining this with the distance between the sample and the film, the angle by which the principal axis of the crystal lattice deviates from the incident beam can be deduced.

The crystallographer asked Jiang Ming to interpret several negatives in succession. The first one had clear spots, the second one had a scattering background caused by surface scratches, and the third one lost its detail due to overexposure.

Jiang Ming wrote down the spot grouping, symmetry axis search, and angle conversion in sequence in a kraft paper notebook. After each result was reported, the other party asked him to go back to the geometric diagram to check it.

"The biggest danger in industrial orientation is mistaking a pretty pattern for a correct one. If the center of the film, the normal to the sample surface, or the ray axis is off, all the subsequent angles will be wrong."

The sample surface must first be polished to an optical plane. The film is usually placed about 30 mm in front of the sample, with a central aperture for the incident beam to pass through. The exposure conditions need to be determined based on the tube current and the target material.

Both copper and molybdenum targets can be used, and the tube voltage can be found in the working range from 30 kV to 40 kV. The orientation accuracy of industrial equipment can be reduced to within 0.5 degrees.

For older tube sources intended for use with 502, crystallologists recommend first performing three exposures with a lower tube current, selecting conditions based on film density and spot edges, to avoid pursuing a complete pattern in one go.

Before the hour was up, Jiang Ming finished copying down the symmetry table of the spots in the germanium crystal in the 111 and 100 directions, the film distance conversion formula, and the sample tilt angle correction steps.

As the Dark Gold Laboratory faded from view, the ripples on the table spread out again. Jiang Ming turned the kraft paper notebook back to the previous page and added the new content after the crystal physics annotations in Qian Xuesen's lecture notes.

The path to public explanation has also been clarified. The principle of crystal diffraction comes from lecture notes and available foreign literature, while the geometric conversion uses the polarization data from the fifth furnace as the entry point for verification.

The next morning, he handed the equipment list to Wu Hanzhang. The first page listed X-ray tubes, adjustable DC high voltage sources of 30 kilovolts or more, photosensitive film, lead plate shielding, and remote timing switches.

After reviewing the target requirements, Wu Hanzhang flipped the list to the back.

"Specialized diffraction equipment is out of the question, and the procurement channels for industrial X-ray tubes also require approval. Can the factory find a substitute?"

"The repair workshop previously received a batch of scrapped medical equipment. The old-style X-ray tubes used in the chest X-ray machine have sufficient tube pressure. Check that batch of wooden crates first."

Da Liu took the warehouse registration slip to the repair workshop, checked the numbers box by box in the dusty old equipment area, and didn't return to 502 until almost noon, pushing a flatbed cart.

The vehicle was covered with old cotton cloth, and two medical X-ray tubes were respectively stuck in wooden frames. The edge of the glass shell of one tube had turned yellow, while the copper target window of the other tube could still be seen at the positive end.

The filament resistance reading of the first tube is open, while the second tube is conducting normally. The nameplate indicates a maximum tube voltage of 50 kilovolts, and the focal spot size and anode cooling method are also intact.

Jiang Ming used a magnifying glass to inspect the glass seal and cathode lead, and then asked Da Liu to clean the dust and rust spots on the surface of the tube shell. The original outline of the copper target window gradually became visible.

The power supply has been secured for the time being, but the high-voltage power supply has become a bottleneck for the next step, as the voltage level of the commonly used DC equipment in the factory is far below the requirements for Laue exposure.

Jiang Ming spread out the high-voltage rectifier diagram of the Yuanlei No. 1 pulse modulator, covered up the energy storage pulse branch, and only kept the transformer, rectifier, filter and protection circuits.

"The high-voltage section was changed to continuous DC operation, the output was reduced to around 35 kV, a current-limiting resistor was connected in series to control the current of the control tube, and a discharge branch and interlocking switch were added."

Fang Xudong used a slide rule to recalculate the reverse withstand voltage of the rectifier and the ripple of the filter capacitor, and wrote the heating conditions during continuous operation next to the circuit diagram.

After listening to the power supply plan, Old Sun pointed with his pipe at the medical tube, then at the thin wooden door of the cubicle.

"You can see the bones in this thing when you look at it. Where do you get the lead plate? Nobody can stand behind a wooden board to turn it on."

Wu Hanzhang picked up the secure phone, first dialed the factory clinic, then contacted the supplies warehouse. After the two calls, the list included an old lead apron, two lead glass observation windows, and several pieces of half-millimeter lead sheet.

The medical room requires the lead aprons to be returned after use, while the warehouse classifies lead sheets as controlled materials, and the issuance, cutting, and surplus materials must be reviewed by the security department.

According to the dimensions drawn by Jiang Ming, Lao Sun made an adjustable angle bracket. The base was stabilized with a thick steel plate, and two adjustment directions, one vertical and one horizontal, were left between the tube base and the sample holder.

The film cassette is designed as a thin, circular box with an entrance aperture in the center. The back is shielded from stray radiation by lead sheets, and the sample holder can read the tilt angle in both axial directions.

Fang Xudong was in charge of the power supply lines, current-limiting resistors, and timing devices. Da Liu cleared out the corners of the cubicle and separated the operating table from the darkroom washing area.

In the evening, the intact X-ray tube was moved into the cubicle.

Jiang Ming measured the filament continuity again and checked the cathode condition by heating it at low pressure. The glass shell quickly lit up with a dark red light, and the current reading remained stable.

According to the test procedure, only low-pressure pipe testing and mechanical alignment were performed that night, while the high-pressure circuit was left for verification the next day.

Old Sun compared the position of the copper target window and the sample holder through the lead glass, then walked around the support while smoking his pipe.

"The hospital's bone scanners are being used to scan stones. If they can actually get a crystal lattice tomorrow, this pile of useless equipment will finally have a new purpose."

Jiang Ming clamped the polished germanium sheet onto the sample holder, leveled the surface normal, and then placed the empty dark box in the predetermined position.

Fang Xudong wrote down the first set of conditions on the test card: 35 kV, 5 mA, 30 seconds, and then clipped the card to the side of the high-voltage rectifier cabinet.

When the compartment was sealed after the power was cut off, the support, lead wall, and exposure parameters were already set.

The first negative is still pressed in the black paper bag in the darkroom, waiting to be put into the cassette the next morning so that the old medical tube can shine the light onto the crystal lattice for the first time.