A catadioptric Cassegrain optical system is described that permits simultaneous operation as an infrared (IR) imager and a millimeter wave (MMW) radar through a common aperture. Separation of IR and MMW focal points is achieved by use of suitable dichroic coatings and substrate materials. We have evaluated our design by building a prototype and measuring its performance in the laboratory, with particular attention given to isolating the degradation suffered by each mode due to the presence of the other. We present our test results and conclude from an analysis of the data that although our design is feasible, improvements are needed both in the design of the secondary element and in the technology for conductive dichroic coatings.
view Abstract Citations (37) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The abundance of carbon in planetary nebulae. French, H. B. Abstract New photoelectric observations of the C II 4267 A, C III 4647, 4650, 4651 A, and C IV 4659 A recombination lines have been obtained for 14 bright planetary nebulae and used to derive carbon abundances for these objects. The results indicate that carbon was enhanced in the progenitor by a factor of about 2 at the time of planetary nebula ejection, presumably from the dredge-up of newly synthesized triple-alphs carbon. It appears that C O is greater than about 1, indicating that the progenitor was a carbon star at that time. Planetary nebulae may be important contributors to galactic carbon enrichment, perhaps equaling or exceeding supernovae in this respect. Publication: The Astrophysical Journal Pub Date: October 1983 DOI: 10.1086/161360 Bibcode: 1983ApJ...273..214F Keywords: Abundance; Carbon Stars; Electrophotometry; Planetary Nebulae; Stellar Evolution; Line Spectra; Recombination Reactions; Astrophysics full text sources ADS | data products SIMBAD (14)
Tunable IR filters with integral electromagnetic drive actuators have been fabricated using the MEMS LIGA process at the University of Wisconsin.Two types of actuators with IR filter loads have been demonstrated: a single-pole solenoid-type actuator and a three-phase electromagnetic stepper motor drive.The IR filters were designed for a tunable range from 8 to 32 µm.The filter and actuator structures are fabricated from electroplated permalloy.Measurements of the magnetic properties of the permalloy show it to be a soft magnetic material with low coercive force (0.3 Oe) and high permeability (-65,000).An IR filter structure with a large displacement stepper motor has been demonstrated.The bi-directional stepper motor had a total travel of 1.7 mm with an average force per step of 2.4 mN (basic step size of 25 µm) at a drive current of 45 mA per phase.This is the first demonstration of a MEMS linear electromagnetic stepping motor.
view Abstract Citations (30) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the association of galaxies and QSOs. French, H. B. ; Gunn, J. E. Abstract It is found from galaxy counts that there is a strong tendency for galaxies at about the plate limit of the 1.2 m Palomar Schmidt telescope to cluster about low-redshift QSOs. The significance of this clustering has been estimated in a nonparametric way using the Kolmogorov-Smirnov test and is found to be significant at the 99 percent level. If a power-law form for the galaxy-QSO cross-correlation function is assumed, the amplitude is the same within the errors to that of the galaxy-galaxy autocorrelation function. Publication: The Astrophysical Journal Pub Date: June 1983 DOI: 10.1086/161015 Bibcode: 1983ApJ...269...29F Keywords: Galactic Clusters; Quasars; Covariance; Cross Correlation; Kolmogoroff-Smirnoff Test; Luminosity; Red Shift; Astrophysics full text sources ADS | data products NED (23) SIMBAD (19)
It is generally assumed that quasi-stellar objects represent phenomena taking place in galaxies. There are at least three lines of reasoning that lead to this viewpoint. First, there appears to be a continuity of properties extending from Seyfert galaxies and N systems to QSOs with the differences between the various groups principally a question of the contrast between the luminous central object and its surrounding galaxy. Since Seyfert galaxies and N systems are definitely in galaxies, it is concluded that QSOs must also be in galaxies which are not directly visible because of the high luminosity of the central object. A second argument is based on the result that QSOs do not appear to differ dramatically in abundances of elements from those which are typical of normal galaxies. With the prevailing view that virtually all the elements heavier than helium originated as a result of stellar processes, it would be concluded that QSOs must be associated with galaxies of stars that produced the heavier elements. A third, rather indirect argument is based on the results of Stockton (see his paper in this volume) and others that QSOs are often found in groups of galaxies and therefore are likely to be located in galaxies themselves (guilt by association). But the fact is that direct evidence that QSOs are in galaxies is sadly lacking.
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