Chromatic Aberration and Optical Power of a Diffractive Bifocal Contact Lens
Atchison, David A., Ye, Ming, Bradley, Arthur, Collins, Michael J., Zhang, Xiaoxiao, Rahman, Harun A., & Thibos, Larry N. (1992) Chromatic Aberration and Optical Power of a Diffractive Bifocal Contact Lens. Optometry and Vision Science, 69(10), pp. 797-804.
Although diffractive contact lenses have been well documented in theory, no definitive experimental data have been reported which confirm that the near image is in fact created by diffraction rather than by refraction. We have tested the diffraction hypothesis for one type of diffractive contact lens (the Hydron Echelon bifocal) experimentally by measuring its longitudinal chromatic aberration in isolation and when worn on the eye. The basis of this test is that, according to theory, diffractive lenses should have chromatic aberration which is opposite in sign to that measured for the eye. Objective measurements of chromatic aberration were made with a focimeter when the lens was in a wet cell. Subjective measurements were made with a Badal optometer when the lens was worn on the eye. Four control experiments were conducted to provide baseline measurements of the eye’s chromatic aberration, against which we compared the results obtained for the diffractive contact lens. The data were also compared with conventional measurements of refractive error obtained by standard subjective techniques and by an automated infrared refractor. Our results showed that the longitudinal chromatic aberration of the diffraction image of the Echelon bifocal lens was about one-half that obtained under the four control conditions: for the naked eye, for the nondiffraction image of the Echelon lens, or for either image of a refractive bifocal contact lens (CIBA Bisoft). These results are consistent with the theoretical prediction that the negative chromatic aberration of a diffractive contact lens should partially cancel the positive chromatic aberration of the human eye. Conversely, it would be difficult to explain these results on the basis of any other known technique for achromatizing the human eye. We therefore conclude that diffraction is responsible for one of the images formed by the Echelon bifocal lens.
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|Item Type:||Journal Article|
|Additional Information:||The contents of this journal can be freely accessed online via the journal’s web page (see link) 12 months after publication. For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: firstname.lastname@example.org|
|Keywords:||autorefractor, bifocal, chromatic aberration, contact lens, diffractive bifocal, eye, simultaneous vision bifocal|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health|
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 1992 Lippincott Williams & Wilkins|
|Deposited On:||28 Sep 2006|
|Last Modified:||11 Aug 2011 03:50|
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