View Feed
Coffee Room
Discuss anything here - everything that you wish to discuss with fellow engineers.
12889 Members
Join this group to post and comment.
mechmagician19 • Jan 29, 2018

hello everyone i am new here i want to share some ideas about night vision technology start uo

hello i am shivam recently perceiving my degree from sapkal college so i am working on project of night vision technology so guies i need your help to expand this here are my views and how to start up this concept and some stuffs about it.
The manufacturing process for night vision devices is complex. Over 400 different steps are needed to make the core component, the image intensifier tube. Manufacturers carry out several major process steps simultaneously in different sections of the plant.
so here are some steps about that are as follows :
  1. The first major step is making the photo-cathode. The manufacturer may buy preformed rounds of glass for the photo-cathode plate from a subcontractor. Workers drop a wafer of gallium arsenide onto the glass and heat it. This begins to melt the gallium arsenide to the glass.
  2. Then the part is put into a press, which firmly binds the gallium arsenide substrate.
  3. Workers then grind and polish the part.
  4. Meanwhile, the glass microchannel plate is formed using a system known as the two-draw process. This begins with a cast or extruded ingot of special formula glass. The ingot is ground into a rod with a diameter of several centimeters. The rod is fitted into a hollow tube of another type of glass. This is called the cladding. The cladding glass will later be etched away, but it gives the fibers more uniformity in the drawing process.
  5. Now the glass is drawn for the first time. The ingot is hung vertically at the top of a furnace. The furnace may be several feet tall. The furnace has very fine temperature control, so that different points along its length can be held at different temperatures. The ingot is heated at the top of the furnace to about 932°F (500°C). A globule of glass forms at the bottom of the ingot, like a drip coming out of a faucet. As the globule falls, it pulls down a single strand of glass, about 0.04 in (1 mm) in diameter. This strand cools as it stretches. Farther down the furnace, the strand is gripped on either side by a traction machine, which rolls along the fiber, forming it to the precise desired diameter. Cutters clip the fiber to a uniform length (about 6 in [15 cm] long) and pass it down into a bundler. Several thousand fibers are bundled together into a hexagon. This hexagonal bundle is then drawn for a second time, giving the two-draw process its name.
  6. The second draw looks much like the first, with the hexagonal bundle suspended at the top of a zone furnace and heated. The fiber is drawn into a hexagonal shape about 0.04 in (1 mm) in diameter. Because the special glass keeps its cross-section properties, the fiber from this second draw is geometrically similar to the larger bundle, with the glass tubes' honeycomb structure still intact, and the whole structure is just reduced in size. (The space between the individual glass tubes has now been reduced to a few hundredths of a millimeter.) The fiber that results from this second draw is also cut and bundled, similar to the first draw.
  7. The resulting bundle of fibers is heated and pressed under a vacuum, which fuses the fibers together. At this point, the fiber bundle is known as a boule. To make the microchannel plates, the boule is cut at a slightly oblique angle into wafer-thin slices. The slices are ground and polished. The plates are then finished with an acid etch to remove the softer cladding glass. Removing the cladding glass opens channels throughout the plate. Each plate is then coated with nickel-chrome.
  8. Next, a film of aluminum oxide is set onto both surfaces, so that each channel can carry electrical charge. This finished microchannel plate can vary in diameter depending on its designated use, but the thickness remains at about 0.04 in (1 mm). The standard size for finished microchannel plates is 0.9 in (25 mm) in diameter, but they can be as large as 4.9 in (12.5 cm) in diameter.
  9. Next, the phosphor screen and tube body are assembled. The screen itself is a small fiber optic disk that may be supplied by a subcontractor. The image intensifier manufacturer must bond the screen to the metal parts that will hold it in the tube, and then apply the phosphor. The screen is dropped into a flange and bonded to it with a ring of a fusable material called frit. Frit is a special glass compound that welds to metal and glass under high heat. Other metal parts are fitted over the screen, making a small, round part. This part is sent on a track through a furnace, which melts the frit, bonding all the components together. After the part is cooled, cleaned, and polished, the phosphor is sprayed or brushed onto the part. A solution of phosphor in water is poured in. The phosphor settles on the screen, and then the water is drained out.
  10. Workers assemble the tube body by fitting together a series of small metal and ceramic rings. Each ring has a precise function, supporting the different parts that will be loaded into the tube. Insulators and conductors are also added at this time. Some sections of the tube body are made of a soft metal called indium. The assembled tube is run through a furnace, and the indium parts melt and fuse, holding the tube together.
  11. When all the main components are manufactured, they are loaded by hand into the tube body. This is extremely delicate work done in a special clean room environment—in the clean room facilities, the workers wear laboratory suits, gloves, and the work stations are protected by plastic sheeting. The parts mechanically lock into place. First the microchannel plate is locked into the body. Then workers tack-weld electrodes to the parts that will carry voltage.
  12. The partially assembled unit is taken next to a piece of equipment called the exhaust station. In the exhaust station, air is removed from the tube, leaving a vacuum. Under the vacuum, the cathode is inserted into place and activated. Once this is done, the body, cathode, and screen are pressed together. Under high pressure, indium interfaces between the parts fuse, joining all the elements permanently.
  13. Next, the image intensifier tube goes through several testing stages to make sure it is activated and working within expected parameters. When the tube is shown to be functioning correctly, workers wire it to its power supply. Then the tube is set into a piece called a "boot," which resembles a simple plastic cup. This boot forms a housing that encapsulates the tube to protect it. The boot is closed and sealed under a vacuum. Now the image intensifier tube is complete. It undergoes several more rounds of testing. The tests may vary depending on the intended use. Thoroughly tested components then move to a final assembly process. Here they are fit into a casing for goggles, gun sights, binoculars, or whatever the end night vision product is.

Share this content on your social channels -