Abstract

To select a suitable photodetector for an adaptive optics scanning laser ophthalmoscope (AOSLO) and evaluate its performance, we characterized the signal and noise properties in the AOSLO photon detection and derived the signal-to-noise ratio (SNR). Using the SNR as the main criterion, we chose the best detector from a selection of four photomultiplier tubes (PMTs) and three avalanche photodiodes (APDs). We conducted a comprehensive evaluation of the performance of the selected detector on our AOSLO. The study presents a practical strategy that can be used to test the photodetector for either initial evaluation or subsequent performance in in-line inspection.

© 2007 Optical Society of America

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References

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  1. A. Roorda, F. Romero-Borja, W. J. Donnelly III, H. Queener, T. J. Hebert, and M. C. W. Campbell, "Adaptive optics scanning laser ophthalmoscopy," Opt. Express 10, 405-412 (2002).
    [PubMed]
  2. J. A. Martin and A. Roorda, "Direct and non-invasive assessment of parafoveal capillary leukocyte velocity," Ophthalmology 112, 2219-2224 (2005).
    [CrossRef] [PubMed]
  3. A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
    [CrossRef]
  4. J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
    [CrossRef]
  5. Y. Zhang, S. Poonja, and A. Roorda, "MEMS-based adaptive optics scanning laser ophthalmoscopy," Opt. Lett. 31, 1268-1270 (2006).
    [CrossRef] [PubMed]
  6. Hamamatsu, Characteristics and Use of Si APD (Avalanche Photodiode), Technical Information SD-28 (Hamamatsu Photonics K. K., Solid Division, 2001), pp. 5, 6.
  7. Hamamatsu, Photomultiplier Tubes--Basics and Applications, 2nd ed. (Hamamatsu Photonics K. K., Solid Division, 1999), pp. 70-72.
  8. F. Robben, "Noise in the measurement of light with photomultipliers," Appl. Opt. 10, 776-796 (1971).
    [CrossRef] [PubMed]
  9. R. H. Webb and G. W. Hughes, "Detectors for scanning video imagers," Appl. Opt. 32, 6227-6235 (1993).
    [CrossRef] [PubMed]
  10. R. H. Webb, "Confocal optical microscopy," Rep. Prog. Phys. 59, 427-471 (1996).
    [CrossRef]
  11. C. J. R. Sheppard and D. M. Shotton, Confocal Laser Scanning Microscopy (Springer-Verlag, 1997).
  12. J. Pawley, "Fundamental limits in confocal microscopy," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1995), pp. 19-38.
  13. R. H. Webb and C. K. Dorey, "The pixelated image," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1990), pp. 41-51.
  14. J. Art, "Photon detectors for confocal microscopy," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1995), pp. 127-139.
  15. J. Robert, "Photomultiplier tubes are versatile components," Biophotonics Int. 10, 30-33 (2005).
  16. Perkin Elmer, Avalanche Photodiodes: A User's Guide (PerkinElmer Optoelectronics Inc., 1998-2003).
  17. P. Vorenkamp and J. P. M. Verdaasdonk, "Fully bipolar, 120-Msample/s10-b track-and-hold circuit," IEEE J. Solid-State Circuits 27, 988-992 (1992).
    [CrossRef]
  18. R. H. Webb, G. W. Hughes, and F. C. Delori, "Confocal scanning laser ophthalmoscope," Appl. Opt. 26, 1492-1499 (1987).
    [CrossRef] [PubMed]
  19. F. C. Delori and K. P. Pflibsen, "Spectral reflectance of the human ocular fundus," Appl. Opt. 28, 1061-1077 (1989).
    [CrossRef] [PubMed]
  20. ANSI, "American National Standard on the safe use of lasers," ANSI Z136.1-2000 (ANSI, 2000).
  21. E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).
  22. P. P. Webb, R. J. McIntyre, and J. Conradi, "Properties of avalanche photodiodes," RCA Rev. 35, 234-278 (1974).
  23. Y. Zhang and A. Roorda, "Evaluating the lateral resolution of the adaptive optics scanning laser ophthalmoscope," J. Biomed. Opt. 11, 014002 (2006).
    [CrossRef] [PubMed]
  24. C. R. Vogel, D. Arathorn, A. Roorda, and A. Parker, "Retinal motion estimation and image dewarping in adaptive optics scanning laser ophthalmoscopy," Opt. Express 14, 487-493 (2006).
    [CrossRef] [PubMed]
  25. G. Asencios, Hamamatsu Corporation, 360 Foothill Road, Bridgewater, N.J. 08807 (personal communication, 2003-2006).
  26. J. L. Duncan, Y. Zhang, and A. Roorda, "Adaptive optics imaging of macular photoreceptors reveals differences in patients with retinitis pigmentosa and cone-rod dystrophy," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 5667/B761 (2006).
  27. Y. Zhang and A. Roorda, "New generation clinically deployable adaptive optics scanning laser ophthalmoscope," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 1810 (2006).
    [CrossRef]

2006

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Y. Zhang, S. Poonja, and A. Roorda, "MEMS-based adaptive optics scanning laser ophthalmoscopy," Opt. Lett. 31, 1268-1270 (2006).
[CrossRef] [PubMed]

Y. Zhang and A. Roorda, "Evaluating the lateral resolution of the adaptive optics scanning laser ophthalmoscope," J. Biomed. Opt. 11, 014002 (2006).
[CrossRef] [PubMed]

C. R. Vogel, D. Arathorn, A. Roorda, and A. Parker, "Retinal motion estimation and image dewarping in adaptive optics scanning laser ophthalmoscopy," Opt. Express 14, 487-493 (2006).
[CrossRef] [PubMed]

J. L. Duncan, Y. Zhang, and A. Roorda, "Adaptive optics imaging of macular photoreceptors reveals differences in patients with retinitis pigmentosa and cone-rod dystrophy," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 5667/B761 (2006).

Y. Zhang and A. Roorda, "New generation clinically deployable adaptive optics scanning laser ophthalmoscope," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 1810 (2006).
[CrossRef]

2005

J. A. Martin and A. Roorda, "Direct and non-invasive assessment of parafoveal capillary leukocyte velocity," Ophthalmology 112, 2219-2224 (2005).
[CrossRef] [PubMed]

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

J. Robert, "Photomultiplier tubes are versatile components," Biophotonics Int. 10, 30-33 (2005).

2002

1996

R. H. Webb, "Confocal optical microscopy," Rep. Prog. Phys. 59, 427-471 (1996).
[CrossRef]

1993

1992

P. Vorenkamp and J. P. M. Verdaasdonk, "Fully bipolar, 120-Msample/s10-b track-and-hold circuit," IEEE J. Solid-State Circuits 27, 988-992 (1992).
[CrossRef]

1990

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

1989

1987

1974

P. P. Webb, R. J. McIntyre, and J. Conradi, "Properties of avalanche photodiodes," RCA Rev. 35, 234-278 (1974).

1971

Arathorn, D.

Art, J.

J. Art, "Photon detectors for confocal microscopy," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1995), pp. 127-139.

Asencios, G.

G. Asencios, Hamamatsu Corporation, 360 Foothill Road, Bridgewater, N.J. 08807 (personal communication, 2003-2006).

Campbell, M. C. W.

Carroll, J.

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Chung, M.

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Conradi, J.

P. P. Webb, R. J. McIntyre, and J. Conradi, "Properties of avalanche photodiodes," RCA Rev. 35, 234-278 (1974).

Delori, F. C.

Donnelly, W. J.

Dorey, C. K.

R. H. Webb and C. K. Dorey, "The pixelated image," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1990), pp. 41-51.

Duncan, J. L.

J. L. Duncan, Y. Zhang, and A. Roorda, "Adaptive optics imaging of macular photoreceptors reveals differences in patients with retinitis pigmentosa and cone-rod dystrophy," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 5667/B761 (2006).

Elmer, Perkin

Perkin Elmer, Avalanche Photodiodes: A User's Guide (PerkinElmer Optoelectronics Inc., 1998-2003).

Frishman, L. J.

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

Furness, T. A.

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

Harwerth, R. S.

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

Hebert, T. J.

Hughes, G. W.

Johnston, R.

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

Martin, J. A.

J. A. Martin and A. Roorda, "Direct and non-invasive assessment of parafoveal capillary leukocyte velocity," Ophthalmology 112, 2219-2224 (2005).
[CrossRef] [PubMed]

McIntyre, R. J.

P. P. Webb, R. J. McIntyre, and J. Conradi, "Properties of avalanche photodiodes," RCA Rev. 35, 234-278 (1974).

Nagata, S.

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

Parker, A.

Pawley, J.

J. Pawley, "Fundamental limits in confocal microscopy," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1995), pp. 19-38.

Pflibsen, K. P.

Poonja, S.

Pryor, H.

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

Queener, H.

Rangaswamy, N. V.

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

Robben, F.

Robert, J.

J. Robert, "Photomultiplier tubes are versatile components," Biophotonics Int. 10, 30-33 (2005).

Romero-Borja, F.

Roorda, A.

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Y. Zhang, S. Poonja, and A. Roorda, "MEMS-based adaptive optics scanning laser ophthalmoscopy," Opt. Lett. 31, 1268-1270 (2006).
[CrossRef] [PubMed]

Y. Zhang and A. Roorda, "New generation clinically deployable adaptive optics scanning laser ophthalmoscope," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 1810 (2006).
[CrossRef]

J. L. Duncan, Y. Zhang, and A. Roorda, "Adaptive optics imaging of macular photoreceptors reveals differences in patients with retinitis pigmentosa and cone-rod dystrophy," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 5667/B761 (2006).

C. R. Vogel, D. Arathorn, A. Roorda, and A. Parker, "Retinal motion estimation and image dewarping in adaptive optics scanning laser ophthalmoscopy," Opt. Express 14, 487-493 (2006).
[CrossRef] [PubMed]

Y. Zhang and A. Roorda, "Evaluating the lateral resolution of the adaptive optics scanning laser ophthalmoscope," J. Biomed. Opt. 11, 014002 (2006).
[CrossRef] [PubMed]

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

J. A. Martin and A. Roorda, "Direct and non-invasive assessment of parafoveal capillary leukocyte velocity," Ophthalmology 112, 2219-2224 (2005).
[CrossRef] [PubMed]

A. Roorda, F. Romero-Borja, W. J. Donnelly III, H. Queener, T. J. Hebert, and M. C. W. Campbell, "Adaptive optics scanning laser ophthalmoscopy," Opt. Express 10, 405-412 (2002).
[PubMed]

Sheppard, C. J. R.

C. J. R. Sheppard and D. M. Shotton, Confocal Laser Scanning Microscopy (Springer-Verlag, 1997).

Shotton, D. M.

C. J. R. Sheppard and D. M. Shotton, Confocal Laser Scanning Microscopy (Springer-Verlag, 1997).

Verdaasdonk, J. P. M.

P. Vorenkamp and J. P. M. Verdaasdonk, "Fully bipolar, 120-Msample/s10-b track-and-hold circuit," IEEE J. Solid-State Circuits 27, 988-992 (1992).
[CrossRef]

Vilupuru, A. S.

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

Virre, E.

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

Vogel, C. R.

Vorenkamp, P.

P. Vorenkamp and J. P. M. Verdaasdonk, "Fully bipolar, 120-Msample/s10-b track-and-hold circuit," IEEE J. Solid-State Circuits 27, 988-992 (1992).
[CrossRef]

Webb, P. P.

P. P. Webb, R. J. McIntyre, and J. Conradi, "Properties of avalanche photodiodes," RCA Rev. 35, 234-278 (1974).

Webb, R. H.

R. H. Webb, "Confocal optical microscopy," Rep. Prog. Phys. 59, 427-471 (1996).
[CrossRef]

R. H. Webb and G. W. Hughes, "Detectors for scanning video imagers," Appl. Opt. 32, 6227-6235 (1993).
[CrossRef] [PubMed]

R. H. Webb, G. W. Hughes, and F. C. Delori, "Confocal scanning laser ophthalmoscope," Appl. Opt. 26, 1492-1499 (1987).
[CrossRef] [PubMed]

R. H. Webb and C. K. Dorey, "The pixelated image," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1990), pp. 41-51.

Williams, D. R.

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Wolfing, J. I.

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Zhang, Y.

Y. Zhang, S. Poonja, and A. Roorda, "MEMS-based adaptive optics scanning laser ophthalmoscopy," Opt. Lett. 31, 1268-1270 (2006).
[CrossRef] [PubMed]

Y. Zhang and A. Roorda, "Evaluating the lateral resolution of the adaptive optics scanning laser ophthalmoscope," J. Biomed. Opt. 11, 014002 (2006).
[CrossRef] [PubMed]

Y. Zhang and A. Roorda, "New generation clinically deployable adaptive optics scanning laser ophthalmoscope," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 1810 (2006).
[CrossRef]

J. L. Duncan, Y. Zhang, and A. Roorda, "Adaptive optics imaging of macular photoreceptors reveals differences in patients with retinitis pigmentosa and cone-rod dystrophy," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 5667/B761 (2006).

Appl. Opt.

Biophotonics Int.

J. Robert, "Photomultiplier tubes are versatile components," Biophotonics Int. 10, 30-33 (2005).

IEEE J. Solid-State Circuits

P. Vorenkamp and J. P. M. Verdaasdonk, "Fully bipolar, 120-Msample/s10-b track-and-hold circuit," IEEE J. Solid-State Circuits 27, 988-992 (1992).
[CrossRef]

Invest. Ophthalmol. Visual Sci.

J. L. Duncan, Y. Zhang, and A. Roorda, "Adaptive optics imaging of macular photoreceptors reveals differences in patients with retinitis pigmentosa and cone-rod dystrophy," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 5667/B761 (2006).

Y. Zhang and A. Roorda, "New generation clinically deployable adaptive optics scanning laser ophthalmoscope," Invest. Ophthalmol. Visual Sci. 47, E-Abstract 1810 (2006).
[CrossRef]

A. S. Vilupuru, N. V. Rangaswamy, L. J. Frishman, R. S. Harwerth, and A. Roorda, "Adaptive optics ophthalmoscopy for imaging of the lamina cribrosa in glaucoma," Invest. Ophthalmol. Visual Sci. 46, E-Abstract 3515 (2005).
[CrossRef]

J. Biomed. Opt.

Y. Zhang and A. Roorda, "Evaluating the lateral resolution of the adaptive optics scanning laser ophthalmoscope," J. Biomed. Opt. 11, 014002 (2006).
[CrossRef] [PubMed]

J. Laser Appl.

E. Virre, R. Johnston, H. Pryor, S. Nagata, and T. A. Furness III, "Laser safety analysis of a retinal scanning display system," J. Laser Appl. 9, 253-260 (1990).

Ophthalmology

J. A. Martin and A. Roorda, "Direct and non-invasive assessment of parafoveal capillary leukocyte velocity," Ophthalmology 112, 2219-2224 (2005).
[CrossRef] [PubMed]

J. I. Wolfing, M. Chung, J. Carroll, A. Roorda, and D. R. Williams, "High resolution imaging of cone-rod dystrophy," Ophthalmology 113, 1014-1019 (2006).
[CrossRef]

Opt. Express

Opt. Lett.

RCA Rev.

P. P. Webb, R. J. McIntyre, and J. Conradi, "Properties of avalanche photodiodes," RCA Rev. 35, 234-278 (1974).

Rep. Prog. Phys.

R. H. Webb, "Confocal optical microscopy," Rep. Prog. Phys. 59, 427-471 (1996).
[CrossRef]

Other

C. J. R. Sheppard and D. M. Shotton, Confocal Laser Scanning Microscopy (Springer-Verlag, 1997).

J. Pawley, "Fundamental limits in confocal microscopy," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1995), pp. 19-38.

R. H. Webb and C. K. Dorey, "The pixelated image," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1990), pp. 41-51.

J. Art, "Photon detectors for confocal microscopy," in Handbook of Biological Confocal Microscopy, J.B.Pawley, ed. (Plenum, 1995), pp. 127-139.

Hamamatsu, Characteristics and Use of Si APD (Avalanche Photodiode), Technical Information SD-28 (Hamamatsu Photonics K. K., Solid Division, 2001), pp. 5, 6.

Hamamatsu, Photomultiplier Tubes--Basics and Applications, 2nd ed. (Hamamatsu Photonics K. K., Solid Division, 1999), pp. 70-72.

ANSI, "American National Standard on the safe use of lasers," ANSI Z136.1-2000 (ANSI, 2000).

Perkin Elmer, Avalanche Photodiodes: A User's Guide (PerkinElmer Optoelectronics Inc., 1998-2003).

G. Asencios, Hamamatsu Corporation, 360 Foothill Road, Bridgewater, N.J. 08807 (personal communication, 2003-2006).

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Figures (10)

Fig. 1
Fig. 1

Signal light power of the AOSLO.

Fig. 2
Fig. 2

Calculated SNR of photodetectors. (a) Shows the SNRs that were calculated at 680 nm , whereas (b) plots the SNRs that were calculated at 840 nm .

Fig. 3
Fig. 3

Measurement of the SNR of the PMT. L1–L4, lenses; M1–M8, spherical mirrors; AP, artificial pupil; BS1–BS2, beam splitters; DM, deformable mirror; HS, horizontal scanner ( 16 kHz ) ; VS, vertical scanner ( 30 Hz ) ; LA, lenslet array; CP, confocal pinhole; PMT, photomultiplier tube. The retinal conjugate points are marked with “r.”

Fig. 4
Fig. 4

Calculated and measured SNRs of PMT H7422-20 over a bandwidth of 50 MHz . The PMT gain was 1.2 × 10 5 , and the laser wavelength was 660 nm .

Fig. 5
Fig. 5

SNR versus the PMT gain. The PMT gain is approximately 2 × 10 6 V 6.65 , where V is the control voltage of the PMT. The diamonds, squares, and triangles are measured SNRs at different illumination power levels, and the solid lines are theoretical SNRs corresponding to the testing power of the light.

Fig. 6
Fig. 6

SNR versus laser power. The PMT gain is approximately 2 × 10 6 V 6.65 , where V is the control voltage of the PMT.

Fig. 7
Fig. 7

Comparison between calculated and measured SNRs of PMT H7422-20 over a bandwidth of 10 MHz . PMT gain varies from 7.0 × 10 4 to 1.0 × 10 6 . The light wavelength is 840 nm .

Fig. 8
Fig. 8

(a) Single frame taken from a retinal location about 1.2° from the foveal center of a human subject with the PMT H7422-20 and the 680 nm superluminecent laser diode. The field of view of this image is 1.2° or about 360 μ m on a side. The light power at the cornea was 60 μ W , and the PMT gain was 2 × 10 5 . (b) Single frame taken from roughly the same retinal location of the same subject with the 840 nm superluminecent laser diode. The image size is about 1.3° or about 390 μ m on a side. The light power at the cornea was 300 μ W , and the PMT gain was 2 × 10 5 . The eye was dilated. All images have been corrected for distortions due to eye movements.[24]

Fig. 9
Fig. 9

SNR of five photodetectors with an ideal transimpedance amplifier. (a) Shows the SNRs that were calculated at 680 nm , whereas (b) plots the SNRs that were calculated at 840 nm .

Fig. 10
Fig. 10

Comparison between calculated and measured SNRs of a PMT H7422-40 over a bandwidth of 50 MHz . The light wavelength is 660 nm .

Tables (1)

Tables Icon

Table 1 Characteristics of Seven Photodetectors

Equations (15)

Equations on this page are rendered with MathJax. Learn more.

I N 2 = 2 e B G 2 N F ( I P + I D ) + I A 2 ,
I A 2 = i in 2 B ,
I D = I D S + G I D G .
I N 2 = 2 e B G 2 F ( I P + I D G ) + 2 e B I D S + I A 2 .
SNR = I P G 2 e B G 2 N F ( I P + I D ) + i a 2 B ,
SNR = I P G 2 e B G 2 F ( I P + I D G ) + 2 e B I D S + i a 2 B .
B α ( 300 r d ) f l t d ,
n p = P η c h λ Δ t .
N P = G I P e Δ t ,
N D = G I D e Δ t .
N A = I A e Δ t = i a 2 B e Δ t .
SNR = N P N F ( σ P 2 + σ D 2 ) + σ A 2 ,
SNR = N P N F ( N P + N D ) + i a 2 B ( Δ t ) 2 e 2 .
SNR = I P Δ t N F ( I P + I D ) e + i a 2 B ( Δ t ) G 2 .
SNR = I P Δ t e F ( I P + I D G ) + e I D S G 2 + i a 2 B ( Δ t ) G 2 .

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