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Aim: The study was conducted for management of foliar nematode, Aphelenchoides besseyi through different treatment modules in tuberose, Polianthes tuberose. Methodology: A field experiment was carried out with seven treatment modules with four replications to assess the efficacy of treatment modules to manage the foliar nematode in tuberose variety, Calcutta Double. Observations on germination percentage and spike emergence as well as initial and final nematode population in bulbs and plant growth parameters were analysed.? Results: The experiment was conducted with naturally infected plant of tuberose bearing an initial nematode population per five bulbs. The per cent change over treated bulb was found significantly different from the control. The experiment revealed that the germination percent of tuberose bulbs increased under the treatment modules compared to untreated control. Emergence of 55 per cent and 100 per cent spike in treatment modules was earlier than the untreated check. Plant growth parameters were superior in treatment modules as compared to control. Symptoms like stunted growth of plants prickle like structures on the scape and flower and hardy brown flowers in untreated plants were not found in the treated plots.? Interpretation: Symptom development in different parts of tuberose plants increased with increase in population of foliar nematode rendering to the unmarketable tuberose plants. Therefore, an urgent need of management of foliar nematode is documented with seven treatment modules and the modules were found effective in managing the nematode population in field condition.

A new optical design of tiled single grating pulse compressor has been proposed, set-up and studied. The parametric space, i.e. the laser beam diameters that can be accommodated in the pulse compressor for the given range of compression lengths, has been calculated and shown to have up to two fold enhancement in comparison to our earlier proposed optical designs. The new optical design of the tiled single grating pulse compressor has an additional advantage of self compensation of various tiling errors like longitudinal and lateral piston, tip and groove density mismatch, compared to the earlier designs. Experiments have been carried out for temporal compression of 650 ps positively chirped laser pulses, at central wavelength 1054 nm, down to ~235 fs in the tiled grating pulse compressor set up with the proposed design. Further, far field studies have been performed to show the desired compensation of the tiling errors takes place in the new compressor.

A simple, sensitive and robust technique is proposed for coherent alignment of tiled grating assembly using wedge plate lateral shearing interferometry. In this technique, two thick glass wedge plates are used to generate interferograms from reflected and diffracted laser beams, from the tiled grating assembly under alignment. This single optical element based interferometric technique is easy to set up, insensitive to the vibrations and provides simultaneous information of both reference as well as error interference patterns, which are used to estimate the alignment errors. Performance of this technique was tested through alignment of two reflective gratings (size 140 mm X 120 mm), with an angular and translation sensitivities of less than 1 μ rad and 50 nm respectively.

In this paper, we report theoretical studies on optimization of a broadband optical parametric amplifier (OPA) with enhanced output stability for chirped pulse amplification. Optimization of various signal, pump, crystal and ambient parameters has been carried out to achieve an output energy fluctuation that is much smaller than the pump fluctuation. Different practical examples of single/multi stage OPAs and single/ multi pass OPAs, operating in many optical cycles and few optical cycles regimes have been considered in our studies. It is shown that apart from several crystal and beam parameter parameters, crystal temperature and inter/ intra crystal losses constitute important parameters which can be varied to achieve stable broadband pulse amplification in an optical parametric amplifier.

Experimental results of a study on the wavelength dependence and the dynamic range of the quadratic response of commercial grade light emitting diodes (LEDs) are reported over a broad spectral range of 680 nm to 1080 nm using ~ 100 fs duration laser pulses from cw mode locked laser oscillator. A large dynamic range of the quadratic response has been demonstrated in a reverse biased LED. The observed dynamic range compares well with that obtained using a biased photomultiplier tube with large internal gain.

A simple technique is presented to generate temporally flat-top shaped laser pulses using electro-optic modulator (Pockels cell). It involves splitting of input laser pulse into two halves of equal intensity and then stacking together with appropriate optical delay to get a temporally flat-top laser pulse. It also allows generation of other pulse shapes by varying the relative intensity, delay, and phase between two halves of the input laser pulse. Temporally flat-top laser pulses of duration ~ 9 ns have been generated using ~ 7 ns duration incident laser pulses from a flash lamp pumped Q-switched Nd:glass laser oscillator. The rise and fall-time of the shaped pulse is limited by speed of electro-optic switch (Pockels cell), which is ~ 2 ns in the present case.

A simple flash lamp pumped Nd:phosphate glass laser oscillator has been designed and set up delivering laser pulses of variable duration from ∼800 ps to 6 ns. It is based on Q-switching and full-wavelength cavity dumping and provides single laser pulse energy of 5 mJ and 11 mJ corresponding to pulse duration of ∼800 ps and 6 ns respectively at an electrical pump energy of 50 J. While the maximum pulse duration is governed by the cavity round trip time, the lower limit is decided by the switching speed of the high voltage pulse to the Pockels cell of the cavity dumper. Output laser pulses have shown enhanced pulse energy stability by dumping the cavity four round trips after the peak buildup. The laser pulses were synchronized with 250 ps positively chirped laser pulse train derived from an independent commercial cw mode locked Nd:fluorophosphate glass laser oscillator. The temporal jitter between these two pulses was measured to be ∼200 ps, limited by the speed of the electronics used.

An experiment was conducted for two consecutive years (2011–12 and 2012–13) to identify resistant brinjal genotypes and evaluate the bio-efficacy of Pseudomonas fluorescens against bacterial wilt incited by Ralstonia solanacearum. None of the tested genotypes was found highly resistant against pathogen. Swarna Shyamali recorded the lowest wilt incidence (2.50% wilted plants) among all the genotypes. Hybrid-41, Swarna Pratibha, Arka Keshav and VNR-60 also showed resistant reaction. Anamika and BE-706 were found highly susceptible to bacterial wilt. Combination of seedling root dip treatment at the time of transplanting and soil drenching at 20 days after transplanting with P. fluorescens gave the lowest wilt incidence (14.75%), highest fruit yield (244.55 q ha−1) and the highest economic returns. However, it was comparable with soil drenching alone with P. fluorescens. The chemical treatments with bleaching powder and streptomycine (streptomicin sulphate 90% + tetracycline hydrochloride 10%) were found inferior to P. fluorescens soil drenching. Wilt incidence by using soil amendment mustard oil cake @ 5 q ha−1 and seedling root dip with P. fluorescens @ 25 g l−1 was at par with the chemical treatments.

An erratum is presented to correct the inadvertent typing mistakes in our paper [Opt. Express 14, 13131 (2006)].

Essential oil from aromatic plants showed strong nematicidal activity in vitro experiments. Among six tested essential oils, percent juvenile mortality was observed in lemon grass (Cymbopogon citratus), 89, 51 as well as in palmarosa (Cymbopogon martini), 80 and 44 at the doses of 500 and 250 ppm respectively at 12 hour of exposure time. However, maximum mortality percentage was observed in C. citratus oil and it registered cent percent mortality at 500 ppm at 24 hours of exposure time. The hatching in both treatments started by 8th day and steeply increased in 10th day. Essential oils at 5 concentrations drastically reduced the total number of J2, as both essential oils showed more than 50% reduction in hatching over control. The minimum cumulative hatching was observed in 1000 ppm in C. citrates oil. The effect of root-dip treatments of tomato seedlings with C. citratus and C. martini significantly reduced total number of root knot galls/per plant, per cent galled area and soil population as compared to control. The minimum number of M. incognita galls was found in C. citratus at 500 ppm it was significantly different from carbosulfan as well as C. martini treatments. The maximum shoot length was found in C. martini followed by C. citratus and carbosulfan at 500 ppm. All the treatments significantly improved the root length than the inoculated plants but they were not significantly different among themselves.

In this paper, a new method for alignment of the pinhole of a spatial filter (SF) has been proposed and demonstrated experimentally. The effect of the misalignment of the pinhole on the laser beam profiles has been calculated for circular and elliptical Gaussian laser beams. Theoretical computation has been carried out to illustrate the effect of an intensity mask, placed before the focusing lens of the SF, on the spatial beam profile after the pinhole of the SF. It is shown, both theoretically and experimentally, that a simple intensity mask, consisting of a black dot, can be used to visually align the pinhole with a high accuracy of 5% of the pinhole diameter. The accuracy may be further improved using a computer-based image processing algorithm. Finally, the proposed technique has been demonstrated to align a vacuum SF of a compact 40 J Nd:phosphate glass laser system.

We report here work done towards development of a two arm, high energy, high power Nd:phosphate glass laser system. One arm of the laser is proposed to be operated in a long pulse (∼1.5ns pulse duration) with an energy of ∼400 J. Presently, this arm of the laser is operating at energy of ∼100 J after a disc amplifier that amplifies the laser beam of diameter ∼94 mm. After the addition of two more disc amplifiers which are nearing completion, the laser beam will have energy of ∼400 J, with a beam diameter 140 mm, at an intensity of ∼2 GW/cm2 . This beam will be converted to its second harmonic using a 2 × 2 array KDP crystals. The second arm, under development, will operate with a hybrid amplification scheme using optical parametric chirped pulse amplification (OPCPA) and conventional amplification using the existing Nd:glass amplifiers to produce 50 TW, 25 J, 500 fs pulse. A tiled triangular pulse compressor is under development for compressing the stretched pulse.