36 citations · 490 across the 45 of their papers we have counts for
24 papers · 1 filter
Wavefront correction with a ferrofluid deformable mirror: experimental results and recent developments
Denis Brousseau, Ermanno F. Borra, Simon Thibaul +7
We present the research status of a deformable mirror made of a magnetic liquid whose surface is actuated by a triangular array of small current carrying coils. We demonstrate that…
Observations of Time Delays in Gravitational Lenses from Intensity Fluctuations: The Coherence Function
Ermanno F. Borra
Measurements of the spectrum of the fluctuations of the output current of the quadratic detector of a telescope can be used to find unresolved astronomical gravitational lenses and…
A cryogenic liquid-mirror telescope on the moon to study the early universe
Roger Angel, Simon P. Worden, Ermanno F. Borra +9
We have studied the feasibility and scientific potential of zenith observing liquid mirror telescopes having 20 to 100 m diameters located on the moon. They would carry out deep in…
Mechanical and Thermal Tests of the Containers of Liquid Mirrors
E. F. Borra, R. Content, G. Tremblay +2
We give a generic description of a liquid mirror system and summarize some practical information useful to making them. We compare laboratory measurements of deformations, due to t…
Nanoengineered Astronomical Optics
E. F. Borra, A. M. Ritcey, R. Bergamasco +5
We describe a technology for the fabrication of inexpensive and versatile mirrors through the use of a new type of nanoengineered optical material composed by the spreading of a se…
Cosmology at Low Redshifts
Ermanno F. Borra
It is argued that it is far more cost effective to carry out some projects with medium-sized dedicated zenith telescopes rather than large steerable telescopes, freeing the later t…
Ferrofluid Based Deformable Mirrors - a New Approach to Adaptive Optics Using Liquid Mirrors
P. Laird, R. Bergamasco, V. Berube +7
The trend towards ever larger telescopes and more advanced adaptive optics systems is driving the need for deformable mirrors with a large number of low cost actuators. Liquid mirr…
Optical Tests of a 3.7-m diameter Liquid Mirror: Behavior under External Perturbations
Gregoire Tremblay, Ermanno F. Borra
We have built and tested a 3.7-m diameter liquid mirror that rotates on a ball bearing. We have carried out extensive optical tests. We find that although the ball bearing has a po…
Astronomical Research with Liquid Mirror Telescopes
Ermanno F. Borra
Liquid mirror telescopes are of interest to Astronomy because of their very low capital and operating costs. Low cost has a potentially revolutionary impact since it allows one to…
Strip Searching for Supernovae
Ermanno F. Borra
The survey of a strip of sky carried out with a zenith-observing 4-m liquid mirror can discover and observe several thousand supernovae/year to z = 1, making it quite competitive w…
Ultra-Thin Floating Mirrors
Ermanno F. Borra, Anna Ritcey, Etienne Artigau
We discuss a new technology that promises large inexpensive mirrors. We argue that it should be possible to tilt a rotating viscous liquid by perhaps as much as a few tens of degre…
A Search for Peculiar Objects with the NASA Orbital Debris Observatory 3-m Liquid Mirror Telescope
R. Cabanac, E. F. Borra, M. Beauchemin
The NASA Orbital Debris Observatory (NODO) astronomical survey uses a transit 3-m liquid mirror telescope to observe a strip of sky in 20 narrow-band filters. In this article, we a…
Astronomical Research with liquid mirror telescopes
E. F. Borra
I discuss the modalities of zenith observing with LMTs, their limitations and advantages. The main limitation comes from the relatively small regions of the sky that LMTs can acces…
Liquid Mirror Telescopes: A Review
E. F. Borra
I review the present status of liquid mirror telescopes. In a nutshell: LMTs do work and several have been built and used. Extensive interferometric tests of liquid mirrors (the la…
Optical Tests of a 2.5-m diameter Liquid Mirror: Behavior under External Perturbations and Scattered Light Measurements
Luc Girard, Ermanno F. Borra
Interferometric tests of a f/1.2 2.5-m diameter liquid mirror show RMS surface deviations about wave/20 and Strehl ratios of order 0.6, showing that it is diffraction limited. The…
Detection of Gravitational Lenses and Measurement of Time Delays from Classical Electromagnetic Radiation Fluctuations
Ermanno F. Borra
I suggest that measurements of intensity fluctuations caused by classical wave interactions can be used to find unresolved gravitational lenses and determine time delays of essenti…
A corrector design using active vase mirrors that allows a fixed telescope to access a large region of the sky
Gilberto Moretto, Ermanno F. Borra
We investigate whether a three-mirror system, having secondary and the tertiary mirrors with surfaces warped by Zernike polynomials generated by active vase mirrors, is suitable to…
Liquid Mirror Telescopes: A progress report
Ermanno F. Borra, Marc Ferrari, Luc Girard +3
We review the present status of liquid mirror telescopes. Interferometric tests of liquid mirrors (the largest one having a diameter of 2.5 meters ) show excellent optical qualitie…
A Study of Cross-Correlation and Breakfinding Algorithms Applied to the Measurements of Redshifts in Very Low Resolution Spectra
R. Cabanac, E. F. Borra
In this article we compare the cross-correlation and breakfinder techniques applied to the measurements of redshifts from low-resolution spectra. We assume spectra obtained from mu…
THE NEED FOR A PARADIGM SHIFT IN OPTICAL ASTRONOMY: A SOLUTION GIVEN BY LIQUID MIRRORS AND EXAMPLES OF THEIR APPLICATIONS TO COSMOLOGY
E. F. Borra
I argue that there is a crisis in optical Astronomy due to a paucity of telescopes and thus the need for a paradigm shift in telescope technology. Large increases in collecting are…
An Optical Corrector Design That Allows a Fixed Telescope to Access a Large Region of the Sky
E. F. Borra, G. Moretto, M. Wang
We discuss a family of two-mirror correctors that can greatly extend the field accessible to a fixed telescope such as a liquid mirror telescope. The performance of the corrector i…
Liquid Mirrors: A Review
Ermanno F. Borra
The surface of a spinning liquid takes the shape of a paraboloid that can be used as a reflecting mirror. This very old and nearly forgotten concept has recently been revived and I…
Are BL Lacertae Objects Beamed QSO Remnants?
E. F. Borra
This paper considers the hypothesis that BL Lacertae objects (BLLs) are the beamed remnants of Quasi Stellar Objects. The hypothesis explains why BLLs do not undergo the strong evo…
Ubc/Laval 2.7-Meter Liquid Mirror Telescope
P. Hickson, E. F. Borra, R. Cabanac +3
We report the successful development and operation of a large astronomical liquid-mirror telescope. Employing a rotating 2.7-meter diameter mirror with a surface of liquid mercury,…