Cavity-dumped Argon-ion Laser Research Articles

Microarray analysis of protein–protein interactions based on FRET using subnanosecond-resolved fluorescence lifetime imaging

The detection of protein–protein binding on microarrays using the fluorescence lifetime as a dynamic analytical parameter was investigated in a model system. The assay is based on Förster resonance energy transfer (FRET) and carried out with biotinylated Bovine Serum Albumin and streptavidin, labeled with the commonly used microarray dyes Alexa 555 and Alexa 647, respectively. This efficient FRET donor/acceptor pair was employed in a competitive assay format on three different microarray surfaces. The fluorescence was excited by 200 ps laser pulses from a mode-locked and cavity-dumped argon-ion laser, adapted to an intensified CCD camera as detection unit allowing time resolution with subnanosecond precision. Lifetime maps were recorded according to the Rapid Lifetime Determination (RLD) scheme. Interaction between the proteins could clearly be detected on all formats and resulted in almost complete quenching on CEL Epoxy surfaces upon addition of excess streptavidin labeled the FRET acceptor dye. In this case, the fluorescence lifetimes dropped by 90%, whereas on ARChip Epoxy and ARChip Gel the reduction was 54% and 47%, respectively. Good linearity of the quenching curve was obtained in all cases. The method is applicable to all types of protein interaction analysis on microarrays, particularly in cases where evaluation of fluorescence intensity is prone to erroneous results and a more robust parameter is required.

Improvements in the amplification of ultrashort pulses at megahertz repetition rates: characterization of a six-pass amplifier

We describe a multipass dye laser amplifier pumped by a cavity-dumped argon-ion laser for the amplification of ultrashort pulses at megahertz repetition rates. We present the operation and performance characterization of the system for the amplification of picosecond pulses from a synchronously pumped, cavity-dumped dye laser. We find that the multipass configuration of the amplifier provides conversion efficiencies of ~25% of the available energy provided by the pump laser. These results are consistent with appropriate models for the gain of the amplifier.

Magnetic circular differential scattering in FeF_2

We have used magnetic circular differential scattering to study one- and two-magnon scattering in the antiferromagnet FeF2. The technique is useful in that it permits a spin-resonance-type measurement to be made with visible wavelengths. By synchronization of a cavity-dumped argon-ion laser with an acousto-optic modulator, the benefits of lock-in detection were realized. Using this technique, we have been able to measure the one-magnon g factor in a moderate magnetic field. Measurements of the two-magnon spectrum demonstrate that scattering processes involving Δsz = 2 contribute less than 5% of the observed intensity.

High Speed Holographic Movie Camera

A high speed holographic movie camera system has been developed to investigate the dynamic behavior of cavitation bubbles in liquids. As a light source for holography, a high power multiply cavity-dumped argonion laser is used to record very long hologram series with framing rates up to 300 kHz. For separating successively recorded holograms, two spatial multiplexing techniques are applied simultaneously: rotation of the holographic plate or film and acousto-optic beam deflection. With the combination of these two techniques we achieve up to 4000 single holograms in one series.

Stimulated emission from a Cd1−xMnxTe-CdTe multilayer structure

In this letter we report the first observation of stimulated emission from an optically pumped Cd1−xMnxTe-CdTe multilayer structure. This new laser structure was grown by molecular beam epitaxy and consists of an active superlattice (SL) region containing 25 CdTe quantum wells (Lz∼150 Å) alternating with 24 Cd1−xMnxTe (x∼0.45) barriers (LB∼50 Å). The SL is sandwiched between thicker Cd1−xMnxTe cladding layers. The substrate consists of a 2-μm-thick buffer layer of CdTe on GaAs. The Cd1−xMnxTe-CdTe SL lasers operate at 763–766 nm when optically pumped at ∼25 K with a cavity-dumped argon ion laser which emits 4-ns light pulses (514.5 nm) at a repetition rate of 3.8 MHz. The onset of laser action occurs at a peak pump power density of about 1.35×104 W/cm2. The mode spacing of the emitted laser radiation is in reasonable agreement with the spacing expected from measured cavity dimensions of the Cd1−xMnxTe-CdTe multilayer.

A high repetition rate amplifier for the synchronously pumped cavity dumped dye laser

A high repetition rate amplifier pumped by a cavity dumped argon ion laser is used with a synchronously pumped cavity dumped rhodamine 590 (R6G) dye laser. A double pass gain of 7 is observed at a repetition rate of 4 MHz. The amplifier gain is characterized as a function of wavelength, pumped energy, and oscillator energy.

High Speed Holocinematography with the Multiply Cavity–Dumped Argon-Ion Laser

AbstractAhigh power multiply cavity-dumped argon-ion laser is used as an illuminating light source for recording hologram series at framing rates up to 25 kHz. For separating successively recorded holograms spatial multiplexing techniques are applied by rotating the holographic plate.

High-speed holocinematography with acoustooptic light deflection

A series of coherent light pulses delivered by a cavity-dumped argon ion laser is used to record series of about 200 holograms with framing rates up to 38 kHz. The individual holograms are spatially separated on the holographic plate by a combination of acoustooptic light deflection and rotation of the plate. The influence of the blurring of the interference fringes due to the motion of the recording material is discussed. Experimental results are shown.

Time-resolved spectra of an intramolecular exciplex

The intramolecular exciplex formed from N,N-methylphenyl 2-ethyl-(2-naphthoyl)amine was studied by time-resolved emission spectroscopy using a cavity-dumped argon ion laser (wavelength, λ = 257.25 nm) and single-photon counting detection. The spectra, taken at several time delays after excitation, show that the excited amine (lifetime, τ f = 1.78 ns) contributes to the exciplex formation. The excited naphthoate (τ f = 7.98 ns) is the major species observed in the late-gated spectrum (31 ns after excitation), its lifetime being larger than that of the exciplex (τ f = 4.27 ns). The results obtained are explained on the basis of the existence of a static quenching and a slow dynamic quenching.

Pulsed spontaneous Raman scattering technique for luminous environments

A gated photon counting system, cavity-dumped argon-ion laser, and a multipass retroreflecting light cell have been combined in a system to enhance spontaneous Raman scattering in luminous background situations. Signal-to-background ratio (SBR) has been improved a factor of 450 over a single-pass cw system with cw power equal to the pulsed average power. The improvement attributable to the gating and cavity dumping the laser is a factor of 30. A factor of 15 improvement is due to the retroreflecting light cell. Temperature and density data obtained from N(2)Q-branch spectra of a luminous methane-air flame are presented to illustrate the utility of the system. A passband fitting technique is introduced to analyze the data.

Cavity-dumped argon-ion laser as an excitation source in time-resolved fluorimetry

Cavity-dumped argon-ion laser as an excitation source in time-resolved fluorimetry

High Speed Holographic Digital Recorder

Concepts, feasibility experiments, and key component developments are described for a holographic digital record/reproduce system with the potential for 1.0 Gbit/sec rates and higher. Record rates of 500 Mbits/sec have been demonstrated with a ten-channel acoustooptic modulator array and a mode-locked, cavity-dumped argon-ion laser. Acoustooptic device technology has been advanced notably during the development of mode lockers, cavity dumpers, beam deflectors, and multichannel modulator arrays. The development of high speed multichannel photodetector arrays for the readout subsystem requires special attention. The feasibility of 1.0 Gbits/sec record rates has been demonstrated.