Search NASA⌕ Search

SEARCH · Search NASA

Results for “Q-SWITCHING”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

190 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO) fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

formaldehyde (HCHO) fluorescence↗
NASA NTRS2017

Picosecond Pulsed Laser Ablation for the Surface Preparation of Epoxy Composites

As part of a technical challenge under the Advanced Composites Program, methods for improving pre-bond process control for aerospace composite surface treatments and inspections, in conjunction with Federal Aviation Administration guidelines, are under investigation. The overall goal is to demonstrate high fidelity, rapid and reproducible surface treatment and surface characterization methods to reduce uncertainty associated with the bonding process. The desired outcomes are reliable bonded airframe structure, and reduced timeline to certification. In this work, laser ablation was conducted using a q-switched Nd:YVO4 laser capable of nominal pulse durations of 8 picoseconds (ps). Aerospace structural carbon fiber reinforced composites with an epoxy resin matrix were laser treated, characterized, processed into bonded assemblies and mechanically tested. The characterization of ablated surfaces were conducted using scanning electron microscopy (SEM), water contact angle (WCA) goniometry, micro laser induced breakdown spectroscopy (uLIBS), and electron spin resonance (ESR). The bond performance was assessed using a double cantilever beam (DCB) test with an epoxy adhesive. The surface characteristics and bond performance obtained from picosecond ablated carbon fiber reinforced plastics (CFRPs) are presented herein.

Palmieri, Frank↗
NASA NTRS2018

Giant Pulse Phenomena in a High Gain Erbium Doped Fiber Amplifier

High gain Erbium Doped Fiber Amplifiers (EDFAs) are vulnerable to optical damage when unseeded, e.g. due to nonlinear effects that produce random, spontaneous Q-switched (SQS) pulses with high peak power, i.e. giant pulses. Giant pulses can damage either the components within a high gain EDFA or external components and systems coupled to the EDFA. We explore the conditions under which a reflective, polarization-maintaining (PM), core-pumped high gain EDFA generates giant pulses, provide details on the evolution of normal pulses into giant pulses, and provide results on the transient effects of giant pulses on an amplifier's fused-fiber couplers, an effect which we call Fiber Overload Induced Leakage (FOIL). While FOIL's effect on fused-fiber couplers is temporary, its damage to forward pump lasers in a high gain EDFA can be permanent.

Li, Stephen X.↗
NASA NTRS2018

High Output Maximum Efficiency Resonator

A diode pumped, solid state laser is provided that can produce over 16 billion, 15 mJ, 10 ns Q-Switched laser pulses with a low measured decay rate. The laser can be integrated into a global biomass measuring instrument, and mounted on the International Space Station (ISS).

Stysley, Paul R.↗
NASA NTRSDate not supplied

TPSAS-NF1676L-11931-DND

Researchers at NASA Langley Research Center have developed an efficient, high repetition rate, pulsed, 2-µm coherent DIAL/IPDA transmitter for CO2 measurements. This transmitter will be employed to measure atmospheric CO2 profiles (by DIAL) initially from a ground platform, and then measure both the atmospheric CO2 profiles (by DIAL) and column densities (by IPDA) from an airborne platform with the potential for measuring CO2 column density from a space-borne platform. The transmitter consists of a pulsed Q-switched ring-cavity Ho:YLF laser operating at 2.05 micron, being pumped by a Tm:fiber laser. The repetition rate can be adjusted from a few hundred Hz to 10 kHz with corresponding energy of 25 to 1 mJ, respectively. This transmitter can be used for direct or coherent detection of CO2 from ground, air or space-borne platform, as it is capable of providing required energy/repetition rate even from space platform. This presentation will describe the details of the injection-seeded highrepetition rate 2-micron transmitter and demonstrate its flexibility for direct or coherent detection of CO2.

Upendra N Singh↗
NASA NTRSDate not supplied

6 um Pulsed OP-GaAs OPO Laser for Unambiguous Water Ice Detection on the Moon and Other Planetary Bodies

NASA demands a laser transmitter for planetary remote sensing to detect water-ice on the Moon and other planetary bodies. Based on the measurement of the Moon Mineralogy Mapper (M3) instrument, the discovery of water ice on the Moon was acclaimed, but the measurement is disputed because OH- and/or H2O-bearing materials share the absorption line around 3 μm wavelength. Lunar Flashlight, another mission project exploring the surface of Moon which will be launched later this year, enables to map the minerals on dark area of the Moon, but could not resolve the above-mentioned ambiguity. The absorption of 6.08 μm light is uniquely associated with the bending resonance of H2O since there is no comparable vibration in confounding OH-bearing materials. 6.08 μm laser between the atmospheric windows: middle-wave infrared (3-5 μm) and long-wave infrared (8-12 μm) has not been commercially available. Our approach is a Q-switched Ho:YLF laser pumped the orientation-pattern Gallium Arsenide optical parametric oscillator (OP-GaAs OPO) for generating high-energy laser pulses at the wavelength of 6.08 μm. In the current design, a 1.94 μm Tm:fiber is used as the pump source. In the compact design, a 1.94 μm laser diode will replace the Tm:fiber laser as the pump source. We will combine this proposed mid-infrared laser with the latest HgCdTe avalanche photodiode (APD) array to design a lidar for detecting water ice on the Moon and Mars from their respective orbits, enabling novel science and in-situ resource utilization. Our instrument is an enabling technology aboard the Artemis program and others.

mid-infrared laser↗
NASA NTRSDate not supplied

Technology Development of a Solid State 266 nm Laser for NASA’s Dragonfly Mission

NASA’s Dragonfly mission is a rotorcraft lander which will explore several geologic locations on Saturn’s moon, Titan and investigate evidence of surface-level prebiotic chemistry as well as search for chemical signatures of water-based and/or hydrocarbon-based life. To perform molecular composition investigations in-situ, the payload includes the Dragonfly Mass Spectrometer (DraMS), being developed at NASA’s Goddard Space Flight Center (GSFC). DraMS will utilize laser desorption mass spectrometry (LDMS) to interrogate surface samples and measure the organic composition. Enabling this science capability is the Throttled Hydrocarbon Analysis by Nanosecond Optical Source (THANOS) laser being developed at NASA-GSFC. The THANOS laser is comprised of a solid state, passively Q-Switched Nd:YAG oscillator which is frequency converted to 266 nm and utilizes a RTP high voltage electro-optic for pulse energy control. The laser outputs <2.0 ns pulses with a maximum energy of approximately 200 uJ which can be emitted in 1 - 50 shot bursts at 100 Hz while performing LDMS science operations. While operating, the laser has the capability to throttle its UV pulse energy output from full attenuation to maximum energy to provide varying levels of fluence on samples in the DraMS instrument. This paper reports the technology development and space qualification effort of the THANOS laser including vibration, thermal vacuum cycling, radiation as well as Titan atmospheric composition optical damage testing performed at NASA-GSFC from 2019 through 2022.

Matthew W Mullin↗