Archive for August, 2007
Friday, August 31st, 2007
Russian presidential adviser on military-technical issues, Aleksandr Burutin, has visited the Sevmash construction yard in Severodvinsk, Arkhangelsk Oblast. Mr. Burutin paid special interest in the plant’s programme on military construction, the implementation of commercial projects and the contract for military and technical cooperation with India. . The visit comes just few weeks after head of the engineering plant was forced to leave his job following delays in Admiral Gorshkov aircraft carrier refit.
Posted in Defence Products Manufacturing Companies | No Comments »
Thursday, August 30th, 2007
The appointments of the new Vice Chief of Army Staff, General Officers Commanding (Army Commanders) of Chandimandir based Western Command, Pune based Southern Command, Training Command and Corps of Signals have been announced.
Vice Chief of Army Staff
Lt Gen Milan Lalitkumar Naidu, presently Army Commander of Army’s Shimla based Training Command is to be the next Vice Chief of Indian Army. He will take over from Lt Gen Deepak Kapoor, who is to be the next Army Chief from 01 Oct 2007.
Lieutenant General Naidu had his early education at St Joseph’s Convent, Bhopal, and to continue his family tradition, joined the National Defence Academy, Khadakvasla, where he excelled in marksmanship (shooting).
Commissioned in the Rajput Regiment in Dec 1967, he has had a long and chequered career having served in all sectors and terrain in India and abroad. As Commanding Officer of 5 Rajput he participated in Op PAWAN in Sri Lanka where he was awarded the Yudh Seva Medal. He has the experience of Commanding a Brigade in the semi desert terrain, a Division in the Plains of Punjab during Op PARAKRAM and a Corps in the High Altitude and Glaciated area.
Selected to attend the Defence Services Staff College Course in Canada, Lt Gen Naidu has also attended the Higher Command Course at the Army War College. He also holds a Post Graduate in Environmental and Ecological Sciences.
Lt Gen Naidu’s forte has been in the field on instruction. Having trained cadets and young officers at the Indian Military Academy and the Infantry School, he has also had the distinction of being the Commandant of Indian Army’s premier officers’ training establishment for combat – The Army War College.
Lt Gen Naidu has had varied operational staff experience at all levels including a stint at the Military Operations Directorate at Army HQs. He was also the Defence Attaché in Germany.
He is a keen sportsman and formed part of the Services team in the National Skeet Shooting Championship in 1968. He still plays golf, tennis and cricket. His leisure hours are devoted to angling, trekking, reading, photography and music.
Lt Gen Naidu is also the recipient of Ati Vishist Seva Medal for distinguished services.
Lt Gen Naidu is married to Mrs Neeharika who is an daughter of Lt Col Awasthy, a veteran of World War II and 1962 Operations.
General Officer Commanding in Chief, Western Command
Lt Gen Tej Kumar Sapru is to be the next General Officer Commanding in Chief (Army Commander) of the Chandimandir (near Chandigarh) based Wesern Command. Lt Gen Sapru who is presently commanding a Corps in terrorism-affected region of J&K, is to replace Lt Gen Daljeet Singh who retires on 31 October 2007. The operational responsibility of the Western Command encompasses the extremely important plains region along the Indo Pak borders.
Lt Gen Sapru, was born at Srinagar (J&K). He had his early education at Punjab Public School, Nabha. He joined the National Defence Academy, Kharakwasla and was commissioned in the Indian Army, in the infantry (The First Battalion of Fourth Gorkha Rifles) in June 1969. He is one of the few officers who witnessed action both on the Western Front and in the erstwhile East Pakistan during the 1971 war with Pakistan.
(more…)
Posted in Indian Army News | No Comments »
Wednesday, August 29th, 2007
Steps have been taken by the three Services to attract more women to join Armed Forces. All officers including Women Short Service Commission (SSC) officers are now eligible to hold substantive rank of Captain, Major and Lt Col after 2, 6 and 13 years of reckonable service respectively. Government has also issued orders extending the tenure of SSC officers including women officers from 10 years to 14 years. The number of posts Arm/Service/Branch tenable by women officers are being constantly reviewed.
While women officers are treated at par with similarly placed male counterparts in terms of recruitment, training, tenure of service, promotion etc, they are, however, not eligible for Permanent Commission except Medical, Nursing and Dental Services. Writ petitions have been filed by three women officers of Air Force against non-grant of Permanent Commission, extension of Commission. The matter is subjudice. Similarly, one retired women officer of Navy has lodged a complaint for the same.
The number of women officer who left the three service during the last three years is 141, 37 and 111 in Army, Navy and Air Force respectively.
The number of serving women officers in the three Services of Defence Forces and their percentage to the total strength are a) Army has 945 women, 2.67% b) Air Force has 739 women, 7% and c) Navy has 236, 2.94%.
Posted in General Indian Armed Forces News | No Comments »
Wednesday, August 29th, 2007
There are 52 FFRs which are non-operational since they have not been re-notified by the State Governments. With the enactment of Forest (Conservation) Act, 1980, as amended in 1989 and the Supreme Court Order dated Oct 30, 2002, the State Governments are insisting on payment of cost of Compensatory Afforestation (CA) and Net Present Value (NPV) for re-notifying the FFRs since use of forest land as FFR has been classified as a non-forestry activity by the Ministry of Environment and Forests (MoEF).
MoEF was requested in August, 2005 to take up the matter with the concerned authorities in the various states for immediate re-notification of 19 FFRs without pre-payment of CA and NPV so that the Army could conduct its necessary training and field firing. MoEF had stated in October, 2005 that for the purpose of compensating or restricting possible adverse impact on environment, CA was being insisted upon according to the guidelines and the rules framed under the Forest (Conservation) Act, 1980 and the said Act would be applicable only on the actual impact area of the FFR and not the entire area. MoEF had advised the Army authorities to place the case of FFRs for exemption from payment of NPV before the Expert Committee constituted by the Supreme Court. This has been done and is being followed up.
At present, 40 notified and 12 acquired Field Firing Ranges (FFRs) are available to the Army for training and field firing.
Posted in Indian Army News | No Comments »
Wednesday, August 29th, 2007
The Indian Army T-72 Tanks have a problem of barrel bursting. The bursting of barrel in T-72 tanks occurred in barrels of Russian origin as well as of Indian origin. The MoD claims that the problem is over by modifying the chemistry of material. T-72’s are a liability considering their performance in Iraq. One Indian Army T-72 tank was blasted by the LTTE guerrillas during IPKF deployment in Sri Lanka.
Subsequently Indian Army purchased T-90S tanks despite stiff resistance by the officers within its ranks and the political opposition. T-90S also suffers unreliability problems as it was purchased despite failing in Indian trials. Heavy Vehicles Factory has so far supplied 181 T-90 tanks to Indian Army. T-90S has not yet shown barrel burst problem but its firing accuracy and distance problems are well known.
Posted in Indian Army News | No Comments »
Wednesday, August 29th, 2007
The High Altitude (Uncongenial Climate) Allowance is payable to the Indian Armed Forces personnel deployed in High Altitude (Uncongenial Climate) areas. It has been enhanced rates for the troops deployed in more difficult, hazardous and isolated areas above 14,000 ft within the existing High Altitude (Uncongenial Climate) Areas at the rate of Rs. 5,600 per month for Officers and Rs. 3,734 per month for Personnel Below Officer Rank with a view to rationalize the High Altitude Allowance. The enhanced allowance is 80% of Siachen allowance and is comparable to Siachen allowance in proportion to the physical hardships being faced by the Armed Force Personnel.
Travel facilities for Armed Forces personnel has been enhanced too.
1. Grant of one additional free rail warrant every year to all ranks of Armed Forces serving in field/high altitude/counter insurgency/counter terrorism operational areas to travel to and from their duty station and Hometown/Selected Place of Residence.
2. All Service personnel would be eligible to avail leave travel concession once in a year to their hometown in India or Selected Place of Residence in India and every alternate year to any place in India in lieu of hometown or Selected Place of Residence without any distance restriction.
Posted in General Indian Armed Forces News | No Comments »
Wednesday, August 29th, 2007
About 54 missing Indian defence personnel of 1971 War are believed to be in the custody of Pakistan. Pakistan has as usual denied the presence of any such personnel in its custody. The Government has been pursuing this issue with Pakistan for a long time.
This issue was taken up with the Pakistan Government at various levels on a number of occasions. Recently, during the visit of External Affairs Minister to Islamabad in January 2007, the matter was again raised with the President of Pakistan and the latter in turn agreed to a visit by a small group of relatives of missing personnel to Pakistan. Accordingly, a delegation of 14 relatives of missing defence personnel visited 10 jails in different cities of Pakistan from 1st June, 2007 to 14th June 2007, but they could not find any missing defence personnel of 1971 War.
As per laid instructions, a missing person is presumed to be killed if he is not found for 7 years and thereafter his family is given liberalized pensionary awards, which include liberalized family pension, gratuity and education allowance for children. Actions accordingly have been taken in case of missing defence personnel of 1971 War.
Posted in General Indian Armed Forces News | No Comments »
Wednesday, August 29th, 2007
Concerned by the loss of means of livelihood and property due to the major fire at the Army’s biggest ammunition depot at Khundroo in Anantnag district on August 11, the Ministry of Defence (MoD) has decided on a series of measures to provide compensation and relief to the victims. The decisions to this effect were taken last night.
As a first step, MoD will release Rs. 10 crores as an interim assistance to the Jammu & Kashmir State Government to provide relief to the people. The amount will be adjusted against the final payment to be made towards compensation to the State Government.
MoD has also worked out the compensation norms for the people inhabiting areas adjacent to the Ammunition Depot at Khundroo. Those who have suffered complete loss of their Pucca houses will get a compensation of Rs. 1,50,000 per house while for Kutcha houses the compensation will be Rs. 50,000. This is inclusive of the rent for the period till the houses are reconstructed. For partially damaged houses, the compensation will be Rs. 50,000 per Pucca house and Rs. 25,000 per Kutcha house.
The compensation for damages to crops, standing fruit trees, orchards, perennial crops and for cattle and birds killed will be as per the rates specified under norms of assistance from the Calamity Relief Fund as laid down by the Ministry of Home Affairs.
The damage will be assessed by the District Administration and an Officer to be nominated for the purpose by the Chief Secretary of the State Government would work out the compensation or assistance payable in individual cases as per the norms.
It may be mentioned that the families of the persons killed numbering 16 in the incident are being paid Rs. 2.5 lakh each of which Rs. 1.5 lakh is being given by the Army and Rs. 1 lakh by the State Government.
Posted in Indian Army News | No Comments »
Tuesday, August 28th, 2007
The Request for Proposal (RFP) for the procurement of 126 Medium Multi-Role Combat Aircraft (MMRCA) at an estimated cost of Rs. 42,000 crores for the Indian Air Force was issued today to six vendors – Russia’s MIG-35(RAC MiG); Swedish JAS-39 (Gripen);Dassault Rafale (France); American F-16 Falcon (Lockheed Martin); Boeing’s F/A-18 Super Hornet and Eurofighter Typhoon (Made by a consortium of British, German, Spanish and Italian firms). The 211-page document deals with various issues relating to initial purchase, transfer of technology, licensed production and life-time maintenance support for the aircraft. The RFP contains the selection model that would involve an exhaustive evaluation process as detailed in the Defence Procurement Procedures (DPP) – 2006.
The proposals from the likely contenders would first be technically evaluated by a professional team to check for compliance with IAF’s operational requirements and other RFP conditions. Extensive field trials would be carried out to evaluate the performance. Finally, the commercial proposal of the vendors, short-listed after technical and field evaluations, would be examined and compared. The aircraft are likely to be in service for over 40 years. Great care has been taken to ensure that only determinable factors, which do not lend themselves to any subjectivity, are included in the commercial selection model. The selection would be transparent and fair.
Under the terms of purchase, the first 18 aircraft will come in a ‘fly away’ condition while the remaining 108 will be manufactured under Transfer of Technology. The vendor finally selected would also be required to undertake 50% offset obligations in India. The ToT and offset contracts would provide a great technological and economic boost to the indigenous defence industries which would include Defence Public Sector Undertakings, Raksha Udyog Ratnas and other eligible private sector industries. Foreign vendors would be provided great flexibility in effecting tie up with Indian partners for this purpose.
Posted in Indian Air Force News | No Comments »
Monday, August 27th, 2007
Centre for Joint Warfare Studies (CENJOS) was inaugurated in New Delhi today. The Centre for Joint Warfare Studies will function under the Chief of Integrated Staff to the Chiefs of Staff Committee (CISC), headed by Lt Gen HS Lidder. The creation of the centre is a logical step to achieve integration and training of joint warfare professionals. It will train military and civilian professionals in the field of Joint Warfare and Practices. An independent think tank of the Defence Ministry, the Centre will act as a semi autonomous body promoting Joint Warfare Studies at the strategic, operational and tactical levels. It will also cater to various Ministries, Intelligence Agencies and other Government departments associated with Integrated Defence Staff Headquarters in matters of national security.
The prime objectives of the Centre are promotion of joint strategies among the three services and conduct studies and research in joint war-fighting.
Posted in General Indian Armed Forces News | No Comments »
Monday, August 27th, 2007
Laser Science and Technology Centre (LASTEC) is the premier laser lab of DRDO involved in R&D on various laser materials, components and laser systems including High Power Lasers (HPL) for defence-applications. The main charter of the lab revolves around progressing in areas of Photonics, Electro-Optic Counter Measures (EOCM) & HPL. As a defence technology spin off LASTEC has also been engaged in the development of lasers for medical and other civil applications.
Ever since their invention in 1960, Lasers have proven to be a powerful tool with a broad range of applications from barcode scanners to nuclear fusion. The ability of lasers to generate very high radiation density at remote distances with high precision has made it ideally suited for a variety of defence applications. Laser Range Finders and Laser Target Designators are among the most extensively used defence equipments that have revolutionized the present day battlefield scenario. Precision laser guided munitions have proven to be extremely effective against adversaries under all operational conditions. Presently the focus of worldwide military laser research is shifting towards the directed use of laser energy. At moderate energy / power levels several applications have emerged in the field of EOCM for soft kill against optics and EO sensors of the adversary. Hectic development activity in area of HPL and beam control technology (BCT) are being progressed so that Directed Energy System can reach a level of maturity & can be inventoried by the Armed Forces at the earliest.
Say’s Dr. Anil Kumar, the Director of LASTEC “Most of the military laser systems such as laser designators, range finders etc., are based on solid-state lasers. The first laser was also a solid-state laser. It used a synthetic ruby rod (chromium doped aluminum oxide) with mirrors on both ends (one semitransparent) pumped with a helical xenon flash lamp surrounding the rod. Majority of modern solid state lasers now use neodymium (Nd) doped materials such as Nd: YAG (Yttrium Aluminum Garnet which is Y3Al5O12), Nd: YVO4, Nd: Glass and others. These have a much lower lasing threshold than ruby and also possess several other desirable physical and optical properties. The strongest output wavelength of neodymium-doped lasers is around 1,064 nm - near-IR and is invisible to the eye.”
Over the past two and a half decades LASTEC has acquired considerable expertise in the field of solid-state lasers. Flash lamp pumped laser sources based on different types of laser materials like Nd: YAG, Nd: Glass, Nd: Cr: GSGG, Nd: YLF, Ti: Sapphire and Alexandrite have been developed for various kinds of applications including range finding/designation, EOCM, and dual use applications like medical applications. Eye safe radiation generation has been achieved employing both KTP based optical parametric oscillator (OPO) and Er: Phosphate glass laser approaches. Development of flash lamp pumped Zig-Zag Slab Geometry lasers for high average power generation was also carried out employing indigenously developed Nd: Phosphate Glass material. LASTEC is also working on other related technologies including stable and unstable resonator design, nonlinear techniques like frequency conversion (SHG, OPO) and Optical Phase Conjugation (OPC). OPC is preferred tool which can be employed to not only auto point an HPL beam onto a distant target but also to simultaneously compensate for atmospheric aberrations in real time. LASTEC has also been actively involved in the development of state of the art diode pumped solid-state laser technology for developing highly compact, efficient and reliable laser systems. This article presents brief description of some recent achievements with special emphasis on diode pumped solid state lasers and moderate-energy solid state lasers for EOCM applications. Since the article is technically challenging, a highly respected senior scientist from LASTEC, Ms. lalita Agrawal has aided us to make this article technically sound.
1.Flash Lamp Pumped solid state lasers
LASTEC has developed basic technologies for Q-switched solid-state lasers with low energy (40-100 mJ) and peak powers of few MW suitable for range finding and designation applications. However, presently the main focus is to scale up the peak powers for variety of applications e.g. higher harmonic generation for wavelength extension and other nonlinear studies. Moderate energy lasers (1-2 J, 20 ns, 1 Hz) with second harmonic option have been developed for soft EOCM applications. A high-energy (2 kJ, 0.5 ms, single shot) laser system was also developed in collaboration with Russia for permanently damaging the front-end optics of EO systems. Recently, work on high average power of KW level disk geometry lasers has also been initiated that operate in heat capacity mode.
1.1.Dual Role EOCM laser system
A moderate energy laser system with 0.5-0.7 J output at 1064 nm / 0.1 J energy at 532 nm, has been developed and successfully tested at a range of 2.5 km against electro-optic sensors such as silicon photodiodes, CCD cameras and night vision devices. It has been suitably configured as a two men portable tripod mounted system consisting of lasers optic module, laser electronics module and power pack. A built in test system has also been developed to monitor the health of the system. Main Laser Source is based on Q-switched Nd: YAG laser Oscillator –Amplifier scheme. Second Harmonic Generation (532 nm) option including KTP crystal with wavelength selection mechanism has been included for dazzling applications. Transmitter module consists of beam delivery optics for both IR and GREEN wavelengths with desired divergences determined by suitable beam expanders.
Dual Role EOCM laser system
During operation the target is acquired by gross pointing through day/night sights employing pan& tilt arrangement and depending on the application (antisensor/dazzling) suitable wavelength is selected.
Damage caused to various types of the sensors actually depends on the energy density i.e. the spot size at the target and the collecting aperture. Energy density required for human eye dazzling is about five orders less than that for PIN photodiode. Clearly all EOCM class lasers should have much higher energies than required for range-finders/ designators. Typically, the damage thresholds for the semiconductor materials are of the order of 1 J/cm2 for pulsed laser (Nd: YAG, 20 ns). In the case of pulsed lasers, it is always better to use large number of repetitive pulses to disable the sensors because the induced damages are cumulative in nature and hence the preference is for high repetition rate lasers. Since lasers in the visible region only are effective for creating flash blindness (dazzling), the choice for dazzlers is restricted to Alexandrite and frequency doubled Nd lasers. The eye safe levels for these wavelengths are of the order of 5 x 10-7 J/cm2 (20 ns - pulse duration). However exact data is not available in this particular field. In order to have flash blindness, the power level of laser appears to be two or three orders greater than this value. Moreover the laser should have a high repetition rate to achieve this effect efficiently.
Electro-optic sensors are inherently vulnerable to laser attack. Modest power laser beams are sufficient to affect the sensors in many ways. Laser can blind the sensors so that it loses its track, it can confuse the sensors to trigger the explosion of the warhead in uncontrollable manner, and it can overload sensors causing the weapon to malfunction and miss the target. Soft EOCM laser can thus be used to either permanently damage or temporary saturate or confuse the sensors. Hard EOCM laser can employed to permanently damage the front end optics of the EO devices. Similarly human eye is extremely sensitive to visible lasers, which can be employed for temporary blindness or dazzling. Such systems will render the enemy inoperative and confused during both offensive and defensive operations. In fact the EOCM lasers may offer some attractive options like low intensity warfare to fight against the threat of spreading terrorism in the world and contribute significantly to the global peace and stability. International conventions prohibit the use of lasers to damage un-aided eyes. However the convention does not cover laser damages to aided eyes.
After successful demonstration of the Dual Role EOCM system efforts have been initiated to integrate such system with fire control system of tracked vehicles like ICV & tanks including laser threat warner and a low power auxiliary laser for target acquisition.
2.Diode Pumped solid state laser technologies
As a part of DRDO PHOTONICS Programme, LASTEC has successfully developed state of the art Diode Pumped Solid State Laser (DPSSL) Technology. Solid State Lasers are traditionally pumped by noble gas (Xenon or Krypton) filled flash lamps or arc lamps. These lamps produce broad radiation from UV to infrared but only a very small portion of this wide band radiation is used by the absorbing active element. Consequently the electrical efficiency of the system is extremely poor, typically of the order of 1 %. Further, flash lamps have a life of few millions shots and require large banks of energy storage capacitors and charging power supplies. These power supplies generate few kilowatts with high peak currents. However most of these problems have been addressed effectively with the advent of high power laser diodes/arrays and use of the same as pump source for Solid State Lasers. The most attractive feature of laser diodes is their narrow spectral width fitting to the narrow absorption bands of a particular laser material (e.g. Nd: YAG), enabling efficient power, transfer and reduction of thermal loading of the crystal. The small volume resulting from smaller power supply & heat exchanger , enables compact lightweight laser systems. The low driving voltage is an additional advantage. Longer life and high reliability reduces the maintenance cost of the laser. The frequency stability and line width of DPSSL is also better than that of lamp pumped lasers due to decrease in noise because of the reduced need for cooling and more stable pump sources. Such a technology is poised to make major impact in this century.
Several critical techniques including side and end pumping configurations, pulsed and CW mode operation, laser diode driver electronics etc. have been successfully established at LASTEC leading to the development of various demonstration prototypes of DPSSL.
2.1.Passively Q-switched Diode Pumped Nd: YAG laser Prototype
A highly compact passively Q-Switched, diode pumped Nd: YAG laser system generating ~ 5 mJ @10 pps in 20 ns has been developed, which will lead to the development of ultra compact, high rep-rate laser systems for various military applications. The System combines advantages of both diode pumping and passive Q-switching techniques (using Cr:YAG saturable absorber) that result in compact and robust system with much simpler design than their conventional counterparts.
Diode Pumped Nd: YAG laser Prototype
2.2.Diode Pumped Microchip Lasers
Solid-state diode pumped microchip lasers are perhaps the ultimate in miniaturization of diode pumped lasers with extremely good spatial profile, single longitudinal mode and ultra short pulse durations. These lasers are formed by application of dielectric mirror coatings directly to the two parallel surfaces of a thin slice of gain material e.g. Nd: YVO4, Nd: YAG. The short cavities can lead to inherently good mechanical stability as well as single-frequency operation. The short cavity lifetime is useful for the generation of short (sub nanosecond) pulses.
miniaturization of diode pumped lasers
The microchip technology for generation of tens of milliwatts to hundreds of milliwatts of CW power in red, green and blue region is being widely explored all over the world. Microchip lasers find applications not only in industrial and scientific fields but they can also lead to ultra-compact lasers for defence applications.
2.2.1.Palm Top Green Laser Module
LASTEC has developed a palm top green laser module generating 50 mW power @ 532 nm in CW mode. It is based on a diode pumped Nd: YVO4 microchip laser with KTP crystal for intracavity second harmonic generation.
Palm top green laser
Palm top green laser
The module contains a 500 mW laser diode (808 nm) with integrated driver as the pump laser. A short focal length lens has been employed for focusing the beam inside the monolithic microchip laser. This laser has been also configured for short range dazzling applications by incorporating pseudorandom mode of operation.
2.2.2.High Rep Rate (70 kHz) NdYVO4 laser
Passive Q-switching of continuously pumped Nd: YVO4 has been achieved that generated ~ 16 ns wide pulses at ~ 70 KHz repetition rate. An Nd: YVO4 crystal of thickness 1mm and (3 x 3) mm cross-section was end pumped by a CW laser diode with maximum output power of 700mW @ 808nm. A Cr: YAG crystal with 90% initial transmission and an output coupler of 300mm radius of curvature (ROC) and 98% reflectivity @ 1064nm was employed. This laser can find applications in precise distance measurements etc.
Laser pulses at 70 kHz
2.3.Diode Pumped Eye safe lasers
A problem associated with most of the current military laser devices is that they can easily cause retinal injury in the eyes of personnel who accidentally view the laser beam even at a distance of many miles. Currently, however, rapid and significant technological innovation is taking place in the field of eye safe lasers for battlefield applications. Also during training of military operators, the use of an eye safe laser becomes highly desirable. Eye safe lasers operating around 1540 nm have the highest permissible ocular exposures as per the ANSI2.136.1-1993 standard (1J/cm2 for single pulses).
LASTEC has achieved considerable success in the field of Er:glass eye safe lasers through which direct generation of 1540 nm is possible. Active and passive Q-switching techniques have been established in both flash lamp pumped and diode pumped configurations. A flash lamp pumped passively Q-switched lab prototype has been developed generating 8 mJ, 35 ns in single shot mode. Also a diode pumped FTIR Q-switched lab prototype has been packaged generating output energy of 2 mJ with 50 ns pulse width @ 3 Hz. Packaging of a high rep rate (upto 20 Hz) laser is also in progress.
FTIR Q-switched Diode Pumped Eye Safe Laser
Passively Q-switched flash lamp pumped Eye safe Laser
Diode pumping has considerably increased the efficiency of Q-switched Er: Glass laser from ~ 0.1% for flash lamp pumping to ~ 0.8%. It is now also possible to operate these devices at much higher repetition rates (> 20 Hz), which were earlier limited by its poor thermal conductivity. Moreover the long fluorescent lifetime (8 ms) and broad pump absorption bandwidth (910 to 1000 nm) of Yb3+ sensitized Er: Glass makes it suitable for laser diode pumping. Employing lesser number of diode arrays operating in ms regime much higher pump input energies are possible for Er: Glass in comparison to Nd: YAG laser, reducing system costs. The broad absorption bandwidth simplifies the laser diode thermal management issues, temperature control of the laser diode even over large temperature ranges is thus not required for low duty cycle lasers.
2.3.1.High Rep Rate Diode Pumped Er: Yb: Glass Eye Safe Laser
High Rep Rate Diode Pumped Er: Yb: Glass Eye Safe Laser
LASTEC has developed a repetitively pulsed Er: Yb: Phosphate Glass eye safe laser employing the cutting edge technology of Diode Pumping and efficient Frustrated Total Internal Reflection (FTIR) Q-switching technique. The laser is capable of generating 8 mJ in 35 5 ns @ 10 Hz with thermoelectric cooling. Such compact, lightweight high rep-rate diode pumped eye safe laser systems shall be highly beneficial for futuristic applications like range finding, lidar, optical communication etc.
2.4.Diode Pumped Nd: YAG Laser transmitter for space applications
Diode pumped Nd: YAG lasers have shown high potential in satellite missions. They have been flown on NASA missions including MOLA and GLAS and have been proposed and funded for future missions especially for remote sensing applications.
In an effort towards development of indigenous space borne laser instrumentation, LEOS (ISRO) has identified LASTEC (DRDO) as a potential partner, which can complement its expertise towards realization of successful space borne laser instruments. In this regard LASTEC is developing one unit of ‘Qualification Model’ and one unit of ‘Flight Model’ of a Diode Pumped Nd: YAG Laser transmitter for space based altimeter. The task is being completed as per a mutually agreed Joint Development Activity with LASTEC carrying out the basic laser design and development including electronics and LEOS providing support in space qualified hardware development and thermal management.
Development of space borne lasers is a highly challenging task. Laser designs must be lightweight, compact, and energy efficient. Optical mounts have to maintain precision alignment during and after launch. Out-gassing materials in space may lead to contamination of laser optics. Electronic components and optical materials must survive low pressure, thermal cycling and radiation exposures.
LASTEC has completed the design and has developed a lab prototype for design validation & performance evaluation. System consists of a diode pumped Nd: YAG laser generating 30 mJ, 10 ns laser pulses at 10 Hz. It employs an Nd: YAG laser rod of 3 x 70 mm dimension which is symmetrically pumped from three sides by laser diode arrays of total output peak power of 1800 W in 200 s @ 808 nm. A Z-shaped crossed porro prism based, electro-optically Q-switched laser resonator configuration is being employed in view of the harsh space environmental qualification requirements.
Diode Pumped Nd: YAG Laser transmitter for space applications
The progress in development of High Power DPSSL in India is however limited by various constraints like availability of High Power Laser Diode Arrays, Good Optical Quality Materials of large sizes etc.
Today DPSSL technology, though costly, brings together the advantages of high efficiency and compactness in comparison to conventional flash lamp pumped laser technology. For military and space-based applications where size, weight, efficiency and reliability are overriding considerations the cost becomes a secondary factor. However increased maturity in diode fabrication, assembly and testing combined with higher volume production will eventually decrease the cost per watt to a level when all solid state lasers will be diode pumped.
Posted in Defence Research and Development, Opinions and Articles | No Comments »
