Lasers for Guidance and Geodesy: Innovations from ITMO University

Lasers - the usual attribute of "the future, which has already come." These indispensable satellites of science fiction epics have long been incorporated into our daily lives and have occupied a lot of niches in it, from medicine to production technologies (not to mention IT). Nevertheless, the development in this area continues, and interest in them from the business and scientific community does not fade.

A vivid example of this is that the past 2015 was declared by the United Nations the year of light and light technologies. Among all light technologies, lasers are one of the most interesting areas not only for studying, but also for commercialization: the annual volume of production of laser radiation sources in the world in 2015 amounted to 10.1 billion dollars, in 2016 it is expected to grow to 10.5 billion
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Back in 2009, Laser Focus World magazine called lasers a “mature” market: on the one hand, work in this direction was no longer a novelty to anyone (and there is no fear that developments in the field of lasers will burst like a soap bubble on a wave of high expectations) On the other hand, interesting discoveries in this field continue to appear almost every year. At this time, for one of the most interesting innovations are ITMO University researchers.

New developments of ITMO University

Scientists at ITMO University have developed two experimental samples of lasers for geodetic tasks and guidance systems. The devices are more efficient and reliable than their Russian counterparts, while they are designed using only domestic components. Now developers are ready to introduce lasers into production (and in the field of creating laser-optical technology only about 160 companies are employed in Russia).

Both devices were developed at the Research Center for Laser Physics (SIC LF) at ITMO University by scientists and designers who work with eye-safe lasers, that is, with a wavelength of 1.5-2.1 micrometers. These lasers are used in geodesy and guidance systems as pulsed light sources for rangefinders.

The principle of operation of new lasers resembles the principle of operation of the radar - a radiation pulse is sent to space and the countdown to the return signal begins. Multiplying the speed of light by the past time and dividing the result in half, we find out the distance to the object that reflected the impulse. As a result, the laser rangefinder allows you to get the accuracy of measuring the distance to several centimeters, while in atmospheric conditions it measures a distance of up to tens of kilometers.

Compact and accurate laser for drone

One of the devices developed by the staff of the Research Center for Laser Physics is an ultra-compact solid-state laser. The compactness index is particularly important in this case, since the main competition in the development of eye-safe lasers for ranging is moving towards the miniaturization of radiation sources (as well as increasing their efficiency and simplifying use).

The laser can be supplied as an OEM product in a packageless version, which significantly reduces its size and weight due to its integration into the rangefinder carrier housing. In addition, the innovative device uses an innovative passive shutter based on nanocrystals, which was developed in collaboration with the State Optical Institute. S.I. Vavilova.

“The use of a passive shutter allows you to significantly simplify the design of the device and increase its reliability, as well as reduce its price. Usually such lasers are made using an active shutter, for example, an electro-optical one. In such cases, very complex devices are obtained that have high-voltage control circuits in their composition, reducing the practical reliability of the device. The passive shutter of our joint development is, simply speaking, just a piece of glass, ”explained Vadim Polyakov, Lead Designer, SIC LF, ITMO University, Head of the Laser Eye Safety Range.

The ease of use of the developed laser is largely determined by the use of a passive Q-switch. In lasers of this type, active Q-factors are most often used, for example, electro-optical or acousto-optical.

The essence of the Q-switch operation is to tear the laser resonator until a certain amount of energy accumulates in the active body. Upon reaching such a level, the modulator closes the resonator and a single impulse is generated - a short and powerful radiation pulse generated from the stored energy.

In the case of an active modulator, the use of complex electrical signals — high-voltage or high-frequency — is required to break the resonator. The passive Q-switch is based on the effect of nonlinear absorption and bleaching of the optical medium in the presence of a powerful intracavity field. The process of closing the resonator in such a modulator occurs without the application of external signals.
The new ultra-compact solid-state laser is designed for portable rangefinders, allows you to measure a distance of up to 3 kilometers and can be used on unmanned aerial vehicles. Scientific research on it has almost been completed, climatic tests have been passed, and the device is ready for mass production.

Powerful lasers for surveying and construction

To solve geodetic and construction problems, as well as for use in guidance systems at ITMO University, more powerful lasers were developed. They allow you to measure a distance of up to 20 kilometers and operate at frequencies of 10 Hz. In the same way as a less powerful laser, this development is designed for use in harsh conditions, that is, at extreme temperatures and other likely physical exertion.

“Now in the domestic range finders lasers with lamp pumping are used, operating at frequencies less than 1 Hz and having a small resource. The upcoming modernization in this industry should create a large domestic market for the implementation of the development. Due to the fact that we have repeatedly reproduced the experimental samples of this laser and carried out all the basic tests for ourselves, we can very successfully integrate into this wave of modernization, ”Vadim Polyakov comments.

Both developments of SIC LF ITMO are designed for a wide temperature range, and the structures are tested for vibration and impact resistance. This allows you to use them in any weather in the field, as well as on board mobile carriers.

Lasers were presented at the exhibition “Photonics. The world of lasers and optics ”, which took place in Moscow on March 14-17. Also, scientists will take part in the International Conference "Laser Optics", which will be held from June 27 to July 1 in St. Petersburg.

What is now working center of laser physics

A laser: Er: YAG (erbium-doped yttrium-garnet) crystal laser is also being developed at the Laser Physics Research Center. Such a laser has an extremely low heat generation, which allows it to operate at a high frequency and provide a high speed system in which it is integrated.

“There are very few instrument implementations of such a laser worldwide. If we can design such a device, it will be a breakthrough technology. It can be used not only for range finders, but also, for example, in technical vision systems. So, having a laser with a high frequency, you can use every pulse of it as a flash for individual pixels during video recording. It's like a flash on the camera, only for video recording and at times brighter. Plus, using the effect of gating, you can use such a vision system in a fog or other scattering medium, taking into account the fact that waves of 1.5-2.1 micrometers scatter in such media worse than visible light and penetrate them better, ”says leading designer SIC LF ITMO University.

The laboratory is also developing laser equipment for information systems. Eye-safe lasers are in demand as sources of radiation in photon communication channels — we have already talked about the developments of the ITMO University in this area in one of our previous materials.