Liquid mirrors - Optical shop tests and contributions to the technology

Borra, E. F.; Content, Robert; Girard, Luc; Szapiel, Stan; Tremblay, L. M.; Boily, E.

doi:10.1086/171550

Cited by 53 publications

(85 citation statements)

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“…With Strehl ratios of order 0.6, the overall quality of the 2.5-m mirror is excellent, comparable to the quality of the 1.5-m liquid mirror previously tested 2 . Misalignement errors between the mirror and the null lenses, particularly those due to the wobbling of the bearing and varying focal length, induce larger aberrations for the fast f/1.2 2.5-m LM than the slower f/2 1.5-m LM.…”

Section: Conclusion Of the Interferometrysupporting

confidence: 69%

“…A ghost image is apparent at the right of the PSF in D. It is subtracted during data reduction. Getting the azimuthally averaged composite PSF involves some technically challenging operations described in 2,3 . Because the light beam encounters a total of 23 surfaces, refracting and reflecting, in its journey from the pinhole to the CCD, there is bound to be a significant contribution from the auxiliary optics in the form of scattered light or parasitic reflections.…”

Section: Scattered Lightmentioning

confidence: 99%

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Optical tests of a 25-m-diameter liquid mirror: behavior under external perturbations and scattered-light measurements

Girard

Borra

1997

Appl. Opt.

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Interferometric tests of a f/1.2 2.5-m diameter liquid mirror show RMS surface deviations ˜ λ/20 and Strehl ratios of order 0.6, showing that it is diffraction limited. The mirror is certainly better than implied by the data because of aberrations introduced by the auxiliary testing optics. We have made detailed studies of the scattered light of the mirror. We have studied the behavior of the mirror under external perturbations. With this article we have reached an important milestone since we now have a good understanding of liquid mirrors.

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Section: Conclusion Of the Interferometrysupporting

confidence: 69%

Section: Scattered Lightmentioning

confidence: 99%

Optical tests of a 25-m-diameter liquid mirror: behavior under external perturbations and scattered-light measurements

Girard

Borra

1997

Appl. Opt.

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“…It is apparent that the image has a sharp near-gaussian core, but has a signi cant excess ux at radii greater than a few arcsec. This halo is stronger than expected for either a conventional mirror, or a liquid mirror (Borra et al 1992). Further investigation is underway to determine the cause, and to attempt to reduce, the strength of the halo.…”

Section: Performancementioning

confidence: 81%

UBC/Laval 2.7 meter liquid mirror telescope

Hickson¹,

Borra²,

Cabanac³

et al. 1994

ApJ

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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, the telescope images a half-degree diameter eld centered at the zenith. Located near Vancouver, British Columbia, it is equipped with a low-noise 2048 2048-pixel CCD detector, operating in TDI mode, which produces continuous imaging of a 20 0 wide strip of sky with 2-minute integration time. Images with FWHM of 2 00 or less are regularly obtained. This image quality is limited only by atmospheric seeing and star-trail curvature. The telescope is equipped with a series of narrow-band lters, designed to produce 40-point spectral energy distributions from 0.4 to 1.0 um of all detected objects. These will allow classi cation and redshift estimation of approximately 10 4 galaxies and 10 3 quasars to a limiting magnitude of R ' 21.

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“…One should be able to circumvent this limit by carving a ditch around the mirror, like we do for mercury mirrors (Borra et al 1992). Pumpdown is probably a poor solution for a high-viscosity liquid.…”

Section: Tilted Liquid Mirrorsmentioning

confidence: 99%

“…The fact that the surface of a liquid rotating in a gravitational field takes the shape of a parabola has been used to make inexpensive mirrors having excellent surface qualities. The technology is young but its performance is well documented by laboratory tests (Borra et al 1992;Girard & Borra 1997;Tremblay & Borra 2000) as well as by observations (Sica et al 1995;Hickson & Mulrooney 1998;Cabanac et al 1998;Hickson & Racine 2007).…”

Section: Introductionmentioning

confidence: 99%

Tiltable rotating liquid mirrors: a progress report

Gagné¹,

Borra²,

Ritcey³

2007

A&A

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Context. We give a progress report on tiltable, nanoengineered, rotating liquid mirrors, which were discussed in previous papers. Aims. We want to develop the technology, improve reflectivities and user-friendliness. The ultimate goal is to demonstrate high-quality liquid mirrors that can be tilted by a few tens of degrees. Methods. We coated hydrophilic liquid substrates that have poor reflectivities with a reflective layer of self-assembling metallic nanoparticles. We analyzed the wavefronts of 1-m diameter mirrors with Ronchi tests, knife-edge tests and point-spread functions (PSFs).Results. There is significant improvement over previous work where the reflecting layer was deposited on hydrophobic oils. While previous work only demonstrated tilted low-reflectivity mirrors, we now test a high-reflectivity 1-m diameter liquid mirror tilted by 45 arcmin. Conclusions. It is considerably easier to coat hydrophilic liquids than hydrophobic ones. We have reached a significant milestone by demonstrating a tilted, highly reflective, liquid mirror. Although this is still an immature technology, it is near the stage where it could be used in astronomy. The remaining technical challenges, for which we propose solutions, are not fundamental and could be overcome with additional work. This will be a worthwhile undertaking, considering the very low cost of liquid mirrors.

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Liquid mirrors - Optical shop tests and contributions to the technology

Cited by 53 publications

References 0 publications

Optical tests of a 25-m-diameter liquid mirror: behavior under external perturbations and scattered-light measurements

Optical tests of a 25-m-diameter liquid mirror: behavior under external perturbations and scattered-light measurements

UBC/Laval 2.7 meter liquid mirror telescope

Tiltable rotating liquid mirrors: a progress report

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