Category: Applications of Fiber Lasers

High-technology laser systems: gas laser holography methods in medicine

Applications of Holography in Ophthalmology

Holography methods require high-technology laser systems and, just like interpherometery, are often used in ophthalmology. Certain researches have high potential in this sphere: three-dimension image of the eye and its parts, studying optical eye features and measuring internal eye structures with the high resolution.

Imaging Internal Eye Structures

Most of the research today is about creating an image of the internal volume of the eye, and developing an optical scheme to make a wide angle holographic photo. One of the experiments used laser with 632 nm and 589 nm to create a hologram of an eye of animal. Cross-polarization was used to avoid parasite and interfering beams from mirror reflections of an eye and a lens. The images of the blood vessels have been made, however, the main purpose of the holography – three-dimensional image of the objects – hasn’t been achieved. It happened because the resolution wasn’t high enough.

High-technology Laser Systems for Fundus Imaging

High-technology laser system with double-beam is used to obtain the fundus hologram, the regular fundus camera has its xenon light source replaced with an argon gas laser, and its emission is used to illuminate the eye fundus and create a bearing beam. The studies show that the gas laser holography methods have relatively low resolution and low contract images, which can be explained by the speckle pattern that affects the general image.

Advantages and Methods of Holography

In general, holography with gas laser is useful to localize intraocular foreign body and to study different processes such as tumors, edemas, amotio, etc. Using single-pass holographic registration allows achieving a better quality of three-dimension images, fluorangiography is a primary method, a luminescence colourant is inserted in blood, and it helps to register the images of fundus.
There is no doubt that holography method has a great potential in the area of biomedical diagnostics, in particular, in ophthalmology, however, it presents certain challenges that prevent animal experiments from showing excellent results. Further optimization of high-technology laser systems parameters need to be done.

Atomic Cooling: scientific laser systems (laboratory laser, laser equipment)

Principles of Atomic Cooling

Since 1976 scientists have been working on the idea of controlling (cooling, trapping) atoms with laser equipment. The atom trapped in the laboratory laser beam absorbs photons and becomes excited; photons can transmit their impulses to the atom. When atoms are de-excited, they reemit photons in random directions. As a result the atom experiences light pressure in the direction of the laser beam spread. Atoms get excited when the frequency drift is similar to the optical transition.
If an atomic gas is irradiated from each side with the laser frequency that is less than that of an atomic transition, the number of slow atoms grows leading to the temperature decrease.

First Experiments in Atomic Cooling

The first atomic cooling experiment was conducted in the laser spectroscopy department of ISAN. Using the laboratory laser in dilatational cooling the transverse velocity is increased due to the growth of fluctuation atom impulses when laser light photons are absorbed and emitted. At some point of dilatational cooling its speed becomes comparable to that of the transverse one and for further dilatational cooling the transverse cooling of the beam has to be performed. First time it was done in the laboratory in 1984, and the record atom temperature of 0.003 K was reached. This temperature is close to the Doppler cooling.

Impact on Atomic Manipulation

All these experiments with scientific laser systems allowed decreasing the energy of neutral atoms to the levels when their space localization with electric, magnetic and laser fields became possible. This opened new opportunities for sharp decreasing the temperature of the atoms that were already cooled down.

Global Research and Techniques

ISAN was the first laboratory in the world to start experiments with controlling the atomic motion with laser equipment. Today there are dozens of laboratories around the world that work on this aspect using different scientific laser systems.
Different methods exist to cool neutral and excited particles (atoms, molecules and their ions), they are based on various dissipation processes. For example, electric cooling of excited particles is done through the collision of hot atoms and cold electron fluid. However, the most popular and effective way to cool neutral atoms (and localized ions as well) is the collision of those atoms and laser beam photons.

Advanced laser systems, technology and equipment for LIDAR

Introduction to LIDAR Technology

LIDAR (light detection and ranging) is a laser technology used for optical remote sensing which allows one to analyze scattered light properties in order to obtain certain information about a distant object.

How LIDAR Systems Work

These advanced laser systems are often used, for example, to collect precise information about Earth surface and its characteristics. The sensor sends out a pulse of light to travel to an object, it reflects off the object and travels back. When the light clashes into an object, the sensor detects the reflected pulse. Then it measures the time necessary for the reflected pulse to return. The light pulse travels with the speed of light which is known and constant; hence, the time is easily converted into distance or as it is called – the range. The information on the position and angle of the laser equipment allows calculating exact coordinates of the object reflected.

Applications of LIDAR Technology

LIDAR technology can be applied in a lot of different areas, from geographical mapping to robotics due to its high configuration capabilities and wavelengths.
There are different types of LIDARs: rangefinder, DIAL and Doppler.
Rangefinders measure a distance between a sensor and a solid object.
DIAL (differential absorption) measures chemical concentrations in the atmosphere (ozone, water vapor, pollution). It emits pulses with two different wavelengths which are set in a specific way, so that a molecule can absorb one of them, but the other can’t. This way the molecule concentration is deduced.
Doppler technique measures an object velocity. When a light pulse travels to a moving object, its wavelength changes a little, and it is called Doppler shift. When the object is moving away from the sensor, the reflected wavelength will be longer, and when the object is moving towards the sensor, the reflected wavelength will be shorter.

Laser diode system in food production

Laser systems in the food industry

It is not a secret that laser systems are the most frequently used tool in different areas of human life, especially, in the industrial sphere. Today lasers make the process of food production easier and faster and help to control the quality of end products.

Detection of counterfeit olive oil

Thus, researchers from Spain have developed laser diode sensor that is able to reveal counterfeit olive oil that is often sold as “extra virgin”. It means that now it is possible to find out fake olive oil with the help of an optical sensor. This device differentiates similar olive oils by the difference in their quality.

Principle of laser diode system operation

The laser diode system includes laser diodes that allow detecting the fluorescence from spoiled oil that differs from that of real “extra virgin”. It should be mentioned that extra virgin oil is produced from pure, cold-pressed olives, while fake oil includes both cold-pressed and processed oil that has worse taste, appearance, and quality. The most popular example is the mixture of pure olive oil and cheaper oil.

Measurement process and data analysis

The principle of laser system operation includes the use of laser diode sensor that is the source of the light measuring the fluorescence emission level and twenty qualities of data. The measurement of these parameters allows the estimation of fake oil presence concentration.

Advantages of the laser diode sensor

The laser diode sensor has been produced with the help of a 3D printer and has numerous advantages such as:

low cost both to manufacture and to operate;
compact size;
on-site analysis;
result generation in real time;
a potential way for quality control.

Impact on olive oil quality control

The problem of olive oil quality is national and even international one. Previously, its solution faced to an obstacle such as expensiveness but now it became real to eliminate counterfeit olive oil very fast and with low costs. Moreover, the frequency of fake olive oil is reducing due to the laser diode system.

Further research and applications

Also, the researchers undertake the study with the aim of laser system operation control using the mixture of different olive oils, even those that were past their “best before” date and analyzed the results by chaotic algorithms.

Practical use in brand protection

Consequently, this method can be used at any time, to be precise, it is able to control the extra virgin olive oil quality until its packaging or after with the aim of fake brands or producer detection.