Abstract

A confocal scanning imager moves an illumination spot over the object and a (virtual) detector synchronously over the image. In the confocal scanning laser ophthalmoscope this is accomplished by reusing the source optics for detection. The common optical elements are all mirrors—either flat or spherical—and the scanners are positioned to compensate astigmatism due to mirror tilt. The source beam aperture at the horizontal scanner is small. Light returning from the eye is processed by the same elements, but now the polygon’s facet is overfilled. A solid-state detector may be at either a pupillary or retinal conjugate plane in the descanned beam and still have proper throughput matching. Our 1-mm avalanche photodiode at a pupillary plane is preceded by interchangeable stops at an image (retinal) plane. Not only can we reject scattered light to a degree unusual for viewing the retina, but we choose selectively among direct and scattered components of the light returning from the eye. One (of many) consequences is that this ophthalmoscope gives crisp and complete retinal images in He–Ne light without dilation of the pupil.

© 1987 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. R. H. Webb, G. W. Hughes, O. Pomerantzeff, “Flying Spot TV Ophthalmoscope,” Appl. Opt. 19, 2991 (1980).
    [CrossRef] [PubMed]
  2. R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscope,” IEEE Trans. Biomed. Eng. BE-28, 488 (1981).
    [CrossRef]
  3. R. H. Webb, “Optics for Laser Rasters,” Appl. Opt. 23, 3680 (1984).
    [CrossRef] [PubMed]
  4. R. H. Webb, “Manipulating Laser Light for Ophthalmology,” IEEE Eng. Med. Biol. Mag. 4, 12 (1985).
    [CrossRef] [PubMed]
  5. M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
    [PubMed]
  6. G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
    [PubMed]
  7. P. Davidovits, M. D. Egger, “Scanning Laser Microscope for Biological Investigations,” Appl. Opt. 10, 1615 (1971).
    [CrossRef] [PubMed]
  8. C. J. R. Sheppard, T. Wilson, “Depth of Field in the Scanning Microscope,” Opt. Lett. 3, 115 (1978).
    [CrossRef] [PubMed]

1985 (1)

R. H. Webb, “Manipulating Laser Light for Ophthalmology,” IEEE Eng. Med. Biol. Mag. 4, 12 (1985).
[CrossRef] [PubMed]

1984 (1)

1982 (2)

M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
[PubMed]

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

1981 (1)

R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscope,” IEEE Trans. Biomed. Eng. BE-28, 488 (1981).
[CrossRef]

1980 (1)

1978 (1)

1971 (1)

Davidovits, P.

Egger, M. D.

Hughes, G. W.

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
[PubMed]

R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscope,” IEEE Trans. Biomed. Eng. BE-28, 488 (1981).
[CrossRef]

R. H. Webb, G. W. Hughes, O. Pomerantzeff, “Flying Spot TV Ophthalmoscope,” Appl. Opt. 19, 2991 (1980).
[CrossRef] [PubMed]

Mainster, M. A.

M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
[PubMed]

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

Pomerantzeff, O.

Sheppard, C. J. R.

Timberlake, G. T.

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
[PubMed]

Trempe, C. L.

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

Webb, R. H.

R. H. Webb, “Manipulating Laser Light for Ophthalmology,” IEEE Eng. Med. Biol. Mag. 4, 12 (1985).
[CrossRef] [PubMed]

R. H. Webb, “Optics for Laser Rasters,” Appl. Opt. 23, 3680 (1984).
[CrossRef] [PubMed]

M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
[PubMed]

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscope,” IEEE Trans. Biomed. Eng. BE-28, 488 (1981).
[CrossRef]

R. H. Webb, G. W. Hughes, O. Pomerantzeff, “Flying Spot TV Ophthalmoscope,” Appl. Opt. 19, 2991 (1980).
[CrossRef] [PubMed]

Wilson, T.

Appl. Opt. (3)

IEEE Eng. Med. Biol. Mag. (1)

R. H. Webb, “Manipulating Laser Light for Ophthalmology,” IEEE Eng. Med. Biol. Mag. 4, 12 (1985).
[CrossRef] [PubMed]

IEEE Trans. Biomed. Eng. (1)

R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscope,” IEEE Trans. Biomed. Eng. BE-28, 488 (1981).
[CrossRef]

Invest. Ophthalmol. Vis. Sci. (1)

G. T. Timberlake, M. A. Mainster, R. H. Webb, G. W. Hughes, C. L. Trempe, “Retinal Localization of Scotomata by Scanning Laser Ophthalmoscopy,” Invest. Ophthalmol. Vis. Sci. 22, 91 (1982).
[PubMed]

Ophthalmology (1)

M. A. Mainster, G. T. Timberlake, R. H. Webb, G. W. Hughes, “Scanning Laser Ophthalmoscopy,” Ophthalmology 89, 852 (1982).
[PubMed]

Opt. Lett. (1)

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (11)

Fig. 1
Fig. 1

Optical schematic of the copupillary earlier SLOs. Only lens LO is common to both incident and return light paths, and the polarizer is needed to reduce the effects of reflections from it.

Fig. 2
Fig. 2

Light paths within the eye. Direct and indirect light are scattered from various points in the retina and its surround. On the right three successive beams hit a retinal vessel with quite different deflections.

Fig. 3
Fig. 3

Optical schematic of the confocal instrument. The beam system is shown, an instantaneous snapshot. Mirrors are shown schematically as transmissive. This is a view of the horizontally deflected beam showing the tilted main mirror and the way its astigmatism is corrected by putting the image of the horizontal scanner at the pupil’s tangential image and the vertical scanner at the sagittal image. P3 is a virtual image of the pupil, converted to a real image at P4 by a microscope objective.

Fig. 4
Fig. 4

Tilting the main mirror introduces some astigmatism in the scan system but is unavoidable with human subjects. The instantaneous (beam) system is not much affected, and the scan astigmatism is compensated at the scanners.

Fig. 5
Fig. 5

Effect of relative sizes of polygon facets and beam diameter (the pupillary image of this plane). Here a 6-mm facet transmits most of the light from a 1-mm beam (our input configuration) but loses nearly half of the light returning from an 8-mm pupil.

Fig. 6
Fig. 6

Throughput is defined as the product of the area filled by the light as it passes a plane and the solid angle into which an element of that area sends the light. The plane at which throughput is smallest controls the whole system, and larger values of throughput will not be used.

Fig. 7
Fig. 7

Electronic schematic of the instrument. The computer is used to generate graphics but is not required. The whole system is run from a crystal clock, with compensation for the detected phase drift of the horizontal scanner.

Fig. 8
Fig. 8

Confocal stop imaged at the retina discriminates between direct and indirect light and causes the retinal vessel to show dark edges.

Fig. 9
Fig. 9

SLO picture of a 100-μm (i.d.) glass tube immersed in oil of nearly matching index. (a) The edges are dark, the tightly confocal view; (b) a central stop produces the Tyndall view.

Fig. 10
Fig. 10

Tightly confocal views photographed from the TV monitor screen. The illumination is He–Ne light (633 nm). Arteries are paler than veins, because oxyhemoglobin is transparent to this light. The specular reflection is from the inner limiting membrane between the vitreous and retina.

Fig. 11
Fig. 11

Three views here are tightly confocal, copupillary, and Tyndall. He–Ne light, pupil not dilated.

Metrics