Application Area

Application of optical fiber technology in medical endoscope

Endoscopy technology has become a powerful tool to promote the development of medical science.The medical endoscope made of optical fiber is widely used in medicine because the optical fiber bundle is soft and can be bent and flexibly inserted into the human body cavity to realize light guide and image transmission.

The optical fiber bundle is inserted into the body cavity through the appropriate way. On the one hand, the light emitted by the external light source is introduced into the body through the optical fiber bundle to illuminate the parts of the body that need to be examined.On the other hand, the optical fiber bundle transfers the observed pathological images of the internal organs out of the body for the doctor to watch or take photos and video recording.

Principle of optical fiber image transmission

Optical fiber image transmission is determined by the characteristics and structure of optical fiber.In order to use optical fiber bundle for image transmission, the optical fiber bundle must have the following conditions:

1. Ideally, each fiber has good optical insulation.Each fiber in the bundle can transmit light independently, without being affected by the surrounding fiber.

2, the two ends of the multiple optical fibers must be related to the arrangement, one to one correspondence.In other words, each optical fiber should be arranged in exactly the same geometric position at the outgoing end and the incident end.

3. The end face of each fiber of the optical fiber bundle can be regarded as a sampling hole, each carrying a pixel.The incident image can be regarded as composed of many pixels of different brightness, and the optical fiber bundle can be regarded as an image disjunction with several sampling holes arranged regularly, which divides the incident image into pixels equal to the number of sampling holes according to the regularity of its arrangement.The pixel size is equal to the sampling aperture, and each fiber passes one pixel independently through its own sampling aperture.
4. Under ideal circumstances, the absolute value of the incident Angle of the light ray at the optical fiber exit end is equal to that of the incident Angle from the optical fiber end, and its symbol is determined by the odd or even number of total internal reflections.An odd number is positive and an even number is negative.This property is useful for transferring images.

These conditions determine that the fiber bundle will keep an image intact as it passes from one end to the other.For example, the image at the incident end is a "loot" shape composed of multiple pixels, and the image at the exit end is still the same "loot" shape.

Optical system of fiber optic endoscope

Fiber optic endoscope, abbreviated as endoscope or fiberoscope.Its optical system usually includes lighting system, observation system and photographic recording system.

1, the lighting system mainly has light source, guide beam, concave lens and other parts.Light from the external light source is transmitted through a guide beam to a concave lens at the end of the endoscope, where it is diverged to obtain a wider illuminated field of view.

2. The observation system mainly includes right-angle roof prism, imaging objective lens, image beam, eyepiece, etc.The imaging light enters the observation system. First of all, the light is turned 90° by the right-angle roof prism and then shot to the imaging objective lens. The objective lens is imaged on one end face of the image transmission beam, and then transmitted to the other end through the optical fiber beam.
3. When photographically recording, the eyepiece in the above-mentioned observation system acts as the camera lens (namely the camera objective lens).When the focus is adjusted and the camera shutter button is pressed, the image is recorded on the photographic plate.

At present, various medical optical fiber endoscopes have been developed.In addition to gastroscopy, cystoscopy, proctoscope, esophagoscope, bronchoscopy, laparoscopy, colonoscopy, children's special endoscope, etc.

Check, the fiber bundle through the suitable way of inserted into the body cavity, external high strength cold light source the light through the guide beam to the apex of endoscopy, shoot the light window, illuminates the internal need to see parts of the body cavity, and the observed images through the observation window prism change direction, and by the objective lens imaging in image transmission beam on the face of unknown again like a bundle to the eyepiece,For the doctor to watch or take pictures, video.

Because the optical fiber bundle of the endoscope has the advantages of soft and flexible bending, the operation is more convenient even if it is inserted into the complex part of the body cavity.

Endoscope has a wide range of applications, and its accessories are constantly being improved.For example, when a biopsy is required during gastroscopy, biopsy forceps may be used to remove a tissue specimen under direct vision.Some are also equipped with pH meter, can directly measure the pH value of the esophagus or gastric mucosa.The endoscope can also be fitted with a radiation detector, which can be used to diagnose some early cancers.In addition, endoscopy can also be used for treatment.Endoscope, for example, can alleviate the pain caused by surgery for a condition that in the past had to be treated only by surgery.Local hemostasis under endoscope can avoid the complicated process of hemostasis under operation, which has obvious effect on alleviating the pain of patients.

Endoscope equipped with high power laser transmission can be used for intracavitary laser treatment.If the intestinal polyp of intestinal lumen tissue hyperplasia, the use of laser endoscope can be conveniently removed.

Application of optical fiber technology in military field

Applications of optical fiber technology in military communications

The application of optical fiber technology in military communications on land mainly includes three aspects: 1) long-range system of strategic and tactical communications;2) LAN for inter-base communication;3) Links between satellite earth stations, radar and other facilities.

Since the advent of the concept of the "information superhighway," the United States has been ahead of the rest of the world in the development of military information superhighways.In June 1992, the Joint Chiefs of Staff issued a framework document called "Samurai C4T" for the U.S. Army's communications and collaborative master plan for the 21st century.

The goal of the Samurai C4T program is to build a global, real-time military communications network, known as the "information ball," as required by the military "information superhighway."It will be a command network that connects soldiers, command posts and various sensors. It will be a responsive C8 system.Its base network is the Defense Information Systems Network (DISN), which consists of ground and satellite military and civilian communications systems.

The C3I system is one of the largest applications of fiber technology in the U.S. Air Force.GTE Inc. won a contract from the U.S. Air Force for the MX Missile Site C3 system. The fiber-optic cable will serve as an interconnection between combat control centers, regional support centers, missile shelters and maintenance facilities. The total length of the line will be 15,000 km, connecting more than 5,000 computers at 4,800 manned and unmanned sites.

The US military also puts forward the idea of configuring dual links of military satellite and optical cable in the main military gateways, so as to make use of the complementarity of the two communication modes' working characteristics and performance characteristics, so as to ensure the anti-destruction of integrated strategic and tactical communications in crisis situations.

Applications of optical fiber technology in radar and microwave systems

Due to the inherent advantages such as low transmission loss and wide frequency band of optical fiber, the application of optical fiber in radar system is firstly used to connect the radar antenna and radar control center, so that the distance between the two can be expanded to 2 ~ 5km from the original 300m when using coaxial cable.Using optical fiber as transmission media, the frequency band can cover X band (8 ~ 12.4GHz) or Ku band (12.4 ~ 18GHz).

The main application of optical fiber in microwave signal processing is optical fiber delay line signal processing.Advanced high resolution radars require signal processing with low loss and high time - bandwidth product.Traditional coaxial delay lines, surface acoustic wave (SAW) delay lines and charge coupled devices (CCD) can not meet the requirements.Although magneto-static wave devices and superconducting delay lines can meet the technical requirements, they are far from practical application.

The optical fiber delay line has the advantages of low loss (in 1 ~ 10GHz frequency band, the loss per unit delay time is only 0.4 ~ 0.1dB/ps), large time bandwidth product (up to 104 ~ 106), wide band width (> 10GHz), large dynamic range, small triple crossing signal, and easy to realize the delay line tracking each other.And it can be packaged into a small box.

The application of optical fiber technology in phased array radar also includes the use of optical fiber delay lines in the phase shift required for the beam-forming of optically controlled phased array radar.In the electro-optic phased array transmitter, integrated optics is used for beamforming, and fiber optic technology is used for flexible remote control of antenna.Broadband optical fiber real-time delay phased array receiver using optical fiber dispersion prism technology.Among them, in addition to the fiber delay line, fiber couplers, wavelength division multiplexing/demultiplexer, integrated optics, polarization preserving fiber, high dispersion fiber, fiber amplifier, fiber grating and other advanced fiber component technologies have been applied.

Fiber optic guided missile

The U. S. Army's fiber-optic guided missile program is primarily used for anti-tank and anti-helicopter gunships.The early design had a range of only 10km.The U.S. Navy's program focuses on air-to-air, air-to-ground and ship-to-ship operations.

The fiber-optic guided missile not only received the attention of the American military, Germany also carried out the development and research, and got the cooperation of France, Italy also joined them, the three countries jointly formulated the tri-lateral fiber-optic missile program.

The Polypheme 20 can be mounted on light or high motor vehicles with a range of 15km, and can be used against didi vision armoured vehicles and helicopters.The Polypheme60 is designed to kill fixed or low-manoeuvrability targets of specific depth with a range of 60km;The Polypheme SM is designed to be launched from submarines at depths of several hundred metres against helicopters or aircraft with a range of 10km.

Fiber-tethered weapons

The fiber-optic remotely operated vehicle is a highly maneuverable, multipurpose wheeled vehicle attached to a trailer at a base station by a single fiber optic cable. It can deliver a variety of reconnaissance devices, sensors and weapons to dangerous war zones for missions such as reconnaissance, mine detection, mine clearance, obstacle clearance and ammunition resupply.

Developed by the Naval Sea Systems Center and the Sandia National Institute, the RFLV is a fiber-optic, channel-like device that can be used for reconnaissance via television and has a range of up to 4,000 meters.

The balloon-borne radar reconnaissance system using the cable has also been developed rapidly. The altitude of the balloon is 600m ~ 6000m, the payload is 100kg ~ 2000kg, and the airborne time is 15 ~ 30 days. It can play a similar role to the high-altitude early warning aircraft.

Fiber optic remote operated underwater vehicle (fiber-optic remote operated underwater vehicle), also known as underwater robot or unmanned submarine, has two types of towed and tethered.With different equipment, topographic mapping, investigation and salvage of sunken ships and aircraft falling into the sea, rescue submarines, installation of anti-submarine monitoring devices, detection and removal of mines, autonomous laying of mines and underwater decoys can be carried out.

Fiber optic hydrophone system

Optical fiber hydrophone detection of underwater acoustic device is the use of optical fiber technology, it is compared with the traditional piezoelectric hydrophone, high sensitivity, large enough dynamic range, the nature of electromagnetic interference resistance, no impedance matching requirements, system "wet end" light quality and the advantages of the structure of arbitrariness, therefore enough to cope with the challenges of the submarine noise technology constantly improving,It meets the requirements of anti-submarine strategies of developed countries and is regarded as one of the key development projects of national defense technology.

Optically controlled flight

Due to electromagnetic interference and electromagnetic pulse radio frequency, high strength, and the new threat (such as directed energy weapons) will be a serious threat to equipped with electric control flying aircraft flight safety, so people have to take the appropriate shielding measures, but this will result in an increase in weight, and optically controlled flight can have the effect of kill two birds with one stone.

For tactical aircraft, if the light-controlled flight replaces the electrically controlled flight, the weight can be saved by about 90 ~ 317kg. Moreover, the optical fiber system can be used not only for flight control, but also to control and monitor the subsystems of the aircraft. The airborne optical fiber system is also important in "stealth" aircraft.This is not a problem with fiber-optic systems, because the noise emitted by kilometers of cables inside the aircraft becomes a source of radiation that is easily detected by radar.

Application of optical fiber technology in the field of security monitoring

Since entering the 21st century, with the development of digital signal processing (DSP) technology and optical fiber sensing technology, a new security technology: optical fiber monitoring technology, has been paid attention to all over the world, and has been rapidly promoted in Europe and the United States and other countries.The technology and the existing various based on traditional electromagnetic effect, that feature point layout of monitoring technology, it USES fiber as the sensing signal into monitoring and signal transmission and external setting device, through the optical fiber, a comprehensive sensor network implementation area, form (linear, plane form, space, regional form) pick vibration detection and voice.

 

The outstanding characteristics of this kind of monitoring technology include:

1. It has concealment and is easy to deploy.Fiber itself is a linear flexible medium, can be hidden, and non-destructive to the building in a variety of environments and areas, the layout of flexible and free, can fully supplement the perimeter alarm, channel alarm and space alarm three review defense line.Its concealment also greatly reduces the intrusion personnel's vigilance to the security equipment.

2, with a prominent anti-destructive.It is because the optical fiber adopts the way of concealed layout, and the technical principle also has confidentiality, unlike the camera and infrared arrester and other traditional technology is well known, easy to identify, avoid and damage;At the same time, the optical fiber probe has no electromagnetic radiation, more anti-electromagnetic interference, based on the electromagnetic and metal effect detection of the common detection device is difficult to find the optical fiber probe, therefore, the possibility of optical fiber monitoring technology is avoided and damage is very low, very destructive.

3, optical fiber has the advantages of long distance of unrelayed transmission, small dependence on energy, the whole monitoring area of the sensor network are laid out without the need for power supply, thus greatly reducing the risk of electronic equipment may be on wood or other material structure building security risks.And the site does not need the power supply system also do not have to worry about the security system caused by power failure.

Optical fiber sensing system is different from general linear or physical block type detection system is easy to be evaded the lack of gap, optical fiber sensing network through three-dimensional cooperative awareness, like a huge neural network, voice picked up from the ground, underground, and space, to the change to the accurate perception of the whole layout area and ring, a full range of intrusion detection for environmental changes,And through the intelligent behavior analysis and pattern recognition, accurate analysis and judgment, the environmental impact that may produce false positives will be eliminated, to ensure that the system to make high accuracy of notification and alarm.