Mobile phone lenses. Lens Design OPTI 696A. Prof. Jose Sasian

Transcription

1 Mobile phone lenses Lens Design OPTI 696A

2 Specifications Typical mobile phone lens specifications Year Focal length 3 mm - 6 mm 3 mm -5 mm 3 mm -5 mm FOV 66⁰ 72⁰ 78⁰ F/# TTL <5.0 mm <5.0 mm <6.0 mm Distortion <1%-2% <1%-2% <1%-2% CRA <24⁰ <30⁰ <33⁰ RI >50% >50% >32% # lens elements

3 Chief ray angle

4 Image quality Example of MTF specifications in fractions of the Nyquist frequency and in cycles/mm for an object at infinity N Q N Q /2 N Q /4 MTF On- >40% >60% >80% axis MTF 0.7 field MTF 1.0 field S>30% T>20% S>20% T>10% S>50% T>40% S>30% T>20% S>70% T>60% S>40% T>30% Nq=1/2Xpixelsize Fc=1/λf#

5 Aberration correction

6 Jo

7 Ning

8 Do

9 Kudo Mihara

10 Tsuruta

11 Yamaguchi US 2004/

12 Recco

13 Lin

14 Chou

15 Shyu

16 Lyu

17 Seung

18 Kang

19 Lin

20 Tsai

21 Suwon-Si

22 Chen

23 Rear camera I-phone 6

24 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.

25 Iwasaki

26 Desensitizing Lens configuration setting for desensitizing a Cooke triplet lens for lens wedge. Units are in mm and degrees. Configuration Focal length Surface #1 tilt 0.1⁰ Surface #2 tilt 0.1⁰ Surface #3 tilt 0.1⁰ Surface #4 tilt 0.1⁰ Surface #5 tilt 0.1⁰ Surface #6 tilt 0.1⁰

27 Choice of surface

28 Aspheric coefficients Shinohara Even and odd Aspheric surfaces

29 Aspheric coefficients Kubota

30 Prescription table Example 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 A 4 STOP E48R OKP E E48R E OKP E-3 10 Plano 0.3 BK7 11 Plano 0.4 Image

31 Materials Properties of some plastics used in mobile phone lenses Code n d v γ ρ 480R x E48R x F52R x OKP x OKP4HT x Water absorption Light scattering and haze Transmission CTE Dn/dt Opto-thermal coefficients Durability Birefringence Links to optical plastics vendors:

32 Zooms/folded

33 Papers 1. P. Clark, Lens design and advanced function for mobile cameras, Chapter 1, in Smart 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 July 2006); doi: / ; 3. Peter P. Clark, "Mobile platform optical design", Proc. SPIE 9293, International Optical Design Conference 2014, 92931M (17 December 2014); doi: / ; 4. M. Schaub, The design of plastic optical systems, SPIE Press, Vol. TT80, Reshidko, D., & Sasian, J. (2015). Optical analysis of miniature lenses with curved imaging surfaces. Applied Optics, 54(28), E216-E223. DOI: /AO.54.00E Yufeng Yan, Jose Sasian, "Miniature camera lens design with a freeform surface", Proc. SPIE 10590, International Optical Design Conference 2017, (27 November 2017); doi: / ;