In this study, the environment inside an operational laser system was monitored over a period of three months using a surface acoustic wave sensor. The environment experienced by the sensor was subject to repeated vacuum pumpdown, nitrogen purge and chemical flow processes. The data collected during this period demonstrated the fact that this type of sensor is subject to both accumulation and desorption mechanisms. Surface conditions were clearly active and changing over time. By tailoring the sensor surface to be equivalent to that of the optical coatings in the system, it was believed that the sensor provided an excellent view of the condition of the surface of those optical coatings. Monitoring a system using a device of this type may, in the near term provide some knowledge of readiness. In the long term, this type of monitoring may assist in the selection of compatible materials and effective design for control of contamination.
The demonstration and characterization of a multiwatt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series parametric studies of the I*(2P1/2) - I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. A reduction in the flow channel height led to improved performance. The highest measured gain was 4.2 x 10-4 cm-1 and the highest power observed was 31 W.
The demonstration and characterization of a multiwatt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series parametric studies of the I*(2P1/2) - I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. A reduction in the flow channel height led to improved performance. The highest measured gain was 4.2 x 10-4 cm-1 and the highest power observed was 31 W.
The demonstration and characterization of a multi-watt All Gas-phase Iodine Laser (AGIL) are described. A 20-cm subsonic reactor was used to produce NCl(a1Δ) for a series of parametric studies of the I*(2P1/2)-I(2P3/2) small signal gain and extracted power dependence on reactant flow rates and reaction time. The highest measured gain was 2.5x10-4 cm-1 and the highest power observed was 18 W.
The Chemical Oxygen- Iodine Laser (COIL) beam of 5.3 kW average power was homogenized by transmitting through a low-loss fiber optic with a rectangular core. The fiber optic integrator transformed the beam into a beam with a uniform illumination. The exit aperture ofthe fiber was then imaged by projection optics and the beam uniformity was analyzed in the image plane. These experiments demonstrated a simple technique ofproviding a highly uniform beam over a large target area by using the low loss fiber. The desired rectangular beam footprints were achieved without the use of an external aperture The beam profiles and power were recorded and analyzed before and after the fiber. The COIL used for this puipose was specially configured for a stable resonator to produce a near-square cross section, low divergence, and multimode beam.
The Air Force Research Laboratory (AFRL) is exploring the feasibility of large-aperture, deployable, space-based membrane telescopes operating in the visible and/or near- infrared spectral regions. One of the near-term goals of this work is to develop an understanding of available and achievable membrane materials, specifically concentrating on practical techniques to form large aperture membranes with the necessary surface quality and economy. When this research began a little more than three years ago, the conceptual design was based upon a totally inflatable structure. An inflatable structure has been used for space solar power collection and radio frequency antennas. This totally inflatable lenticular design is simple and relatively easy to demonstrate, but maintaining inflation during an extended lifetime in near-earth orbit may not be feasible. Recently, a new concept for a membrane telescope has emerged which does not depend on sustained inflation during operation. Thin membranes on the order of 10 to 100 micrometer thick will be packaged and deployed, maintaining their surface figure by means other than inflation. Given the fact that the sub- wavelength level surface tolerances required of imaging telescopes will probably not be practical with a membrane- based telescope, such systems will probably rely on real-time holography or some other wavefront correction or compensation technique. We will discuss the primary experimental work ongoing in the AFRL Membrane Mirror Laboratory, and in doing so, some of the issues relevant to demonstrating a practical, large-aperture membrane mirror system.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.