Diffractive Lenses for Extended Depth Of Focus and Presbyopic...
Transcript of Diffractive Lenses for Extended Depth Of Focus and Presbyopic...
![Page 1: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/1.jpg)
1
Diffractive Lenses for Extended Depth Of Focus and Presbyopic Correction
G. Michael Morris and Dale Buralli Apollo Optical Systems, Inc.
330 Clay Road Rochester, NY 14623
E-mail: [email protected] Web: http://www.apollooptical.com
February 15, 2008
![Page 2: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/2.jpg)
2
Focus of the Presentation:
1. Use of longitudinal chromatic aberration to extend the depth of focus
2. Use of wavefront-splitting methods to create simultaneous-vision bifocal lenses
![Page 3: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/3.jpg)
3
Achromatic Doublets Bring Two Wavelengths To A Common Focus
Lens Powers Abbe Numbers
; Φ = Total Power 20 < νglass < 90 νdiff = −3.45
Conventional Doublet Hybrid Doublet Crown Glass
νa = 60 φa = 2.5 Φ
Flint Glass νb = 36
φb = −1.5 Φ
Crown Glass νa = 60
φa = 0.95 Φ
Diffractive Lens νb = −3.45 φb = 0.05 Φ
Crown Flint
![Page 4: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/4.jpg)
4
Extending the Depth of Focus
• Instead of correcting the chromatic aberration, a hybrid (contact or intraocular) lens may introduce a desired amount of longitudinal chromatic aberration in order to extend the depth of focus.
• Two approaches: – Hyperchromatic lens
All-Refractive (Whitefoot & Charman) Refractive/diffractive (Freeman)
– Multi-order diffractive (MOD) lens (Faklis & Morris) Purely diffractive (no refractive power)
![Page 5: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/5.jpg)
5
Previous Work with Refractive Lenses
Doubled LCA → 0.5 D increase in DOF
![Page 6: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/6.jpg)
6
Conventional Diffractive vs. MOD Lens Concepts
F
Conventional Diffractive Lens
F
Multi-Order Diffractive (MOD) Lens
(a)
(b)
![Page 7: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/7.jpg)
7
Cross Sectional View of Polychromatic (MOD) Diffractive Lens
D. Faklis and G. M. Morris, “Polychromatic diffractive lenses,” U. S. Patent No. 5,589,982, December 31, 1996.
![Page 8: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/8.jpg)
8
Transmission Properties of a MOD Lens
Transmission Function
Focal Length:
Note: Wavelengths λ m,p that satisfy the following equation all focus at a distance F from the lens.
Diffraction Efficiency
; ηm ~ 100% when
Phase Step = 2πp m = Diffraction Order
![Page 9: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/9.jpg)
9
Diffraction Efficiency of a MOD Lens Design parameters: λ0 = 555 nm, p = 10
![Page 10: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/10.jpg)
10
A MOD lens possesses a range of powers or focal lengths, which can be thought of as a type of “natural accommodation”.
Δφ
MOD “Extended Focus Depth” Lens
![Page 11: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/11.jpg)
11
Optical Performance On-axis through-focus MTF; 10 cycles/degree Photopic spectrum Entrance pupil diameter = 4 mm
![Page 12: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/12.jpg)
12
Refractive Lens & MOD Lens Performance Comparison
Asphere -2D
MOD 20 -2D
2.5 mm pupil diameter 5.0 mm pupil diameter
![Page 13: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/13.jpg)
13
Simultaneous Vision Approaches • Aperture segmentation
• Wavefront splitting (diffractive optics)
F1 F2
F1 F2
primary diffraction orders
![Page 14: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/14.jpg)
14
Evaluated Bifocal Designs Theoretical & laboratory investigation of 17 different
bifocal designs, including:
• Aperture segmented – Five-zone design – Two-zone design, center near
• Wavefront splitting (diffractive) – Blazed diffractive (Freeman) – Apodized diffractive (Lee-Simpson) – “Harmony” (Apollo) – MOD lens with diffractive bifocal (Apollo)
![Page 15: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/15.jpg)
15
Diffractive “Harmony” Surface (U.S. Patent No. 7,156,516 B2)
• Diffractive surface formed by superposition of sinusoidal functions.
• Unlike blazed structure, surface is smooth (no sharp-edged transitions).
• Reduced glare & image artifacts
![Page 16: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/16.jpg)
16
Bi-Focal Lens Performance – Laboratory Prototypes
2-zone Bifocal
5-zone Bifocal
Apollo Bifocal [Insensitive to pupil size] 60:40 split (Distance: Near)
2.5-mm Pupil 5.0-mm Pupil Distance Near Distance Near
![Page 17: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/17.jpg)
17
Vision MembraneTM Lens in Anterior Chamber
Curved Vision Membrane Lens bridging over the pupil
Membrane Thickness ~ 500 - 600 µm
![Page 18: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/18.jpg)
18
![Page 19: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/19.jpg)
19
MULTI-FOCAL VISION MEMBRANE
VM = Green arrow
![Page 20: Diffractive Lenses for Extended Depth Of Focus and Presbyopic …voi.opt.uh.edu/16_Morris_DiffractiveLenses.pdf · 2008. 2. 29. · Bi-Focal Lens Performance – Laboratory Prototypes](https://reader036.fdocuments.us/reader036/viewer/2022081614/5fc2c4f07220e176fc2da78b/html5/thumbnails/20.jpg)
20
Conclusions
• With simultaneous vision, wavefront splitting results in higher quality images than aperture segmentation, and minimizes image quality variations at different aperture sizes.
• A controlled (or desired) amount of longitudinal chromatic aberration may be used to extend the depth of focus. – Hyperchromatic correction using a refractive-diffractive hybrid lens – MOD (purely diffractive) lens
• MOD lenses with a diffractive “Harmony” bi-focal design provide an effective (low glare & low halo) simultaneous bifocal design with extended depth of focus for both distance and near vision.