Prof. Jose Sasian

Mobile phone lenses

Lens Design OPTI 696A

Prof. Jose Sasian

Specifications

Typical mobile phone lens specificationsYear 2006 2012 2018Focal length 3 mm - 6 mm 3 mm -5 mm 3 mm -5 mmFOV 66⁰ 72⁰ 78⁰F/# 2.8 2.2-2.4 2.0-1.4TTL <5.0 mm <5.0 mm <6.0 mmDistortion <1%-2% <1%-2% <1%-2%CRA <24⁰ <30⁰ <33⁰RI >50% >50% >32%# lens elements 3-5 4-6 5-8

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Chief ray angle

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Image quality

Example of MTF specifications in fractions of the Nyquist frequency and in cycles/mm for an object at

infinityNQ NQ /2 NQ /4

MTF On-axis

>40% >60% >80%

MTF Off-axis

@ 0.7 field

S>30%T>20%

S>50%T>40%

S>70%T>60%

MTF Off-axis

@ 1.0 field

S>20%T>10%

S>30%T>20%

S>40%T>30%

Nq=1/2XpixelsizeFc=1/λf#

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Aberration correction

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Jo

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Ning

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Do

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Kudo Mihara

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Tsuruta

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YamaguchiUS 2004/0105173

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Recco

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Lin

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Chou

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Shyu

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Lyu

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Seung

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Kang

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Lin

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Tsai

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Suwon-Si

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Chen

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Rear camera I-phone 6

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Manufacturing

For proper plastic flow and cooling, plastic lens manufacturers have some requirements for the aspect ratio of positive and negative lenses. Some guidelines are as follows: for positive lenses the ratio of lens central thickness to edge thickness should not be no more than 3.2, and the edge thickness should not be less than 0.32 mm; for negative lenses the ratio of the maximum thickness to the central thickness should not be larger than 2.7 and the central thickness should not be less than 0.27 mm. The ideal lens for injection molding approaches a lens with parallel surfaces so that plastic flow, cooling, and shrinkage are uniform. For miniature lenses tolerances of 10 µm for thickness, decenter, total indicator runoff and lens tilt, are low; tolerances between 2 µm and 5 µm are medium and feasible to achieve in manufacturing, and tolerances between 0.5 µm and 2 µm are challenging to achieve and are met for some miniature optics.

Prof. Jose Sasian

Iwasaki

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Desensitizing

Lens configuration setting for desensitizing a Cooke triplet lens for lens wedge.

Units are in mm and degrees.Configuration 1 2 3 4 5 6 7Focal length 1

00

Surface #1 tilt 0.1⁰Surface #2 tilt 0.1⁰Surface #3 tilt 0.1⁰Surface #4 tilt 0.1⁰Surface #5 tilt 0.1⁰Surface #6 tilt 0.1⁰

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Choice of surface

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Aspheric coefficientsShinohara

Even and oddAspheric surfaces

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Aspheric coefficients

Kubota

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Prescription tableExample of a four lens element design for a mobile phone lens.

F=5.0 mm, FOV=+/-32⁰, TTL/f=1.4, F/2.8. CRA=30.6⁰.Surface Radius Thickness Plastic K A4

STOP2 3.5432.72 0.87 E48R -3.24573 -4.57977 0.1 -11.72134 126.2449 0.6 OKP4 0.05 3.013807 0.8 -0.9977 -2.533E-36 -8.81693 1.61 E48R 0.0 4.161E-37 -1.61409 1.0 -2.2699 -0.0126713

8 72.73421 0.7 OKP4 0.0 -0.0100888

9 2.101288 0.7 -6.3020 -6.073E-310 Plano 0.3 BK711 Plano 0.4

Image

Prof. Jose Sasian

MaterialsProperties of some plastics used

in mobile phone lensesCode nd v γ ρ480R 1.525 55.95 +1.44x10-4 1.01E48R 1.531 56.04 -2.62x10-4 1.02F52R 1.534 57.09 -2.21x10-4 1.01OKP4 1.607 26.90 -3.44x10-4 1.20

OKP4HT 1.632 23.33 -2.72x10-4 1.24

Links to optical plastics vendors:http://www.ogc.co.jp/e/products/fluorene/okp.htmlhttps://www.zeonex.com/Optics.aspx.html#glass-like

• Water absorption• Light scattering and haze• Transmission• CTE• Dn/dt• Opto-thermal coefficients• Durability• Birefringence

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Zooms/folded

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1. P. Clark, “Lens design and advanced function for mobile cameras,” Chapter 1, inSmart Mini-Cameras, Galstian, T. V. Editor, CRC Press, Boca Raton, FL, (2014).

2. Jane Bareau, Peter P. Clark, "The optics of miniature digital camera modules",Proc. SPIE 6342, International Optical Design Conference 2006, 63421F (25 July2006); doi: 10.1117/12.692291; https://doi.org/10.1117/12.692291

3. Peter P. Clark, "Mobile platform optical design", Proc. SPIE 9293, InternationalOptical Design Conference 2014, 92931M (17 December 2014); doi:10.1117/12.2076395; https://doi.org/10.1117/12.2076395

4. M. Schaub, “The design of plastic optical systems,” SPIE Press, Vol. TT80, 2009.5. Reshidko, D., & Sasian, J. (2015). Optical analysis of miniature lenses with curved

imaging surfaces. Applied Optics, 54(28), E216-E223. DOI:10.1364/AO.54.00E216

6. Yufeng Yan, Jose Sasian, "Miniature camera lens design with a freeform surface",Proc. SPIE 10590, International Optical Design Conference 2017, 1059012 (27November 2017); doi: 10.1117/12.2292653; https://doi.org/10.1117/12.2292653

Papers