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7/8/2013 SMS freeforms for illumination Pablo Benítez, Juan C. Miñano, M. Buljan Universidad Politécnica de Madrid, Spain Benitez, Miñano, Buljan OSA webinar, July 10, 2013 53 Index • Introduction • SMS 3D design method • Application examples • Summary Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 54 27
7/8/2013 Design problems in Nonimaging Optics • Bundle coupling: Source and target ray bundles are given. Maximum coupling efficiency is required. o Collimators o Condenser optics for a projector o Light injection into an optical fiber E(source) E(target) o Radiation sensors o Photovoltaic concentrator • Prescribed illuminance: The source ray bundle and the output illuminance distribution on the target are given. o Automotive headlights o Street lights E(source) < E(target) o RGB color blending o Backlights E = etendue = “ size ” of the ray bundle (in phase space) Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 55 Why freeforms in Nonimaging Optics? • When source, target or volumetric constrains are non- symmetric, symmetric solutions don’t work • Freeforms give you more degrees of freedom • Freeforms allow for fewer surfaces and parts because they can perform multiple functions Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 56 28
7/8/2013 Design methods in Nonimaging Optics 1. String method (1960’s) 2. Flow line method (1970’s) 3. Taylored Edge- ray method (1980’s) 2D 4. Poisson bracket method (1980’s) 2D and 3D 5. Lorentz geometry method (1990’s) 6. Point- source Differential Equation methods (1960’s) 7. Numerical optimization methods (1990’s) 8. Simultaneous Multiple Surface (SMS) method (1990’s) 2D = rotational or linear symmetry 3D = freeform Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 57 The SMS 3D WF i2 WF i1 • The method solves a partial functional differential equation optical optical • The solution is given as path path 2 free-form a collection points of the length length optical surfaces L 1 surfaces and their L 2 normal vectors. WF o1 • Those points can be WF o2 interpolated or fitted with a NURBS surface Additional boundary condition : A full curve in one of the surfaces, which can be calculated to partially control a third wavefront pair Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 58 29
7/8/2013 Single freeform vs SMS freeforms H H V V H H V V SMS freeform surfaces Single freeform surface • Design controls THREE points of the • Design controls the position of ONE source image point of the source image • Therefore, it DOES control its size, shape and rotation. • It does NOT control its size, shape and rotation Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 59 Example 1: Low beam headlamp design It is a prescribed illuminance problem Specs defined by regulations (ECE, SAE) Typically 20 min/ max test points/ fields Gradient Specifications Homogeneity Car producer additional specifications Horizontal Spread Low glare values Gradient/Cut-off Elbow/ Shoulder Hotspot Low foreground Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 60 30
7/8/2013 Freeform RXI automotive headlamp Seed rib Spines Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 61 Freeform RXI automotive headlamp Measured efficiencies: • 84% HB (Al mirror; AR coatings) • 75% LB (Al mirror; no AR coatings) US 7,460,985 & International patents pending Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 62 31
7/8/2013 Freeform RXI automotive headlamp Jewel Eye ™ LED headlamps of the 2014 Acura RLX Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 63 Example 2: RBG collimator It is bundle coupling and prescribed illuminance problem y z x freeform collimator Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 32
7/8/2013 Unwanted effects Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 65 Example of freeform solution The grooved 8-fold collimators (M. Buljan et al. SPIE conference, Barcelona, 2012) RXI XX Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 66 33
7/8/2013 8-fold grooved XX collimator Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 67 Step 1: Design a freeform XX • Input data: LED source dimensions, the angle Front mirrored of collimation, collimator’s material. surface • SMS 3D design procedure is applied Back mirrored surface Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 68 34
7/8/2013 Step 2: Design a grooved back reflector ( q,r ) ( -q,-r ) ( q,r ) ( q,-r ) z y While a single reflector at z=0 only changes the sign of r , the groove reflector also changes the sign of q Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 69 Step 2: Design a grooved back reflector ( p,-q,-r ) ( p,q,r ) ( q,r ) ( -q,-r ) z z y Groove edge line y x Both reflectors leave the p coordinate unchanged Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 70 35
7/8/2013 Step 2: Design a grooved back reflector q p Single reflector ( p,-q,-r ) ( p,q,r ) q z y p Groove Groove edge line reflector x Both reflectors leave the p coordinate unchanged Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 71 Step 2: Design a grooved back reflector WF B WF A D. Grabovičkić, P. Benítez, J.C. Miñano “Free -form V-groove reflector design with the SMS method in three dimensions," Opt. Express 19 , A747-A756 (2011) Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 72 36
7/8/2013 Step 3: Apply an 8-fold symmetry Why? See next slides… Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 73 Simulation results y Emitting point-source on z= 0 plane x Far-field distribution No grooves Grooved Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 74 37
7/8/2013 Far-field constallation y Emitting point-source on z= 0 plane x Far-field distribution q p Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 75 Far-field constallation y Emitting point-source on z= 0 plane x Far-field distribution q 45º 45º p Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 76 38
7/8/2013 Far-field constallation y Emitting point-source on z= 0 plane x Far-field distribution 90º 90º q p Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 77 Far-field constallation y Emitting point-source on z= 0 plane x Far-field distribution 135º 135º q p Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 39
7/8/2013 Far-field constallation y Emitting point-source on z= 0 plane x Far-field distribution q p Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 79 Far-field constallation y Emitting point-source on z= 0 plane x Far-field distribution q p Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 80 40
7/8/2013 Simulation results • Far field image when red LED is ON: • Design without grooves (left) • Design with grooves on the secondary mirror (center) • Design with grooves on both primary and secondary mirror(right) Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 81 Simulation results True color far-field images of an RGGB LED • No grooves (left) • 8-fold free-form V-groove collimator (center) • 8-fold free-form V-groove collimator + 2 deg gaussian diffuser (right) Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 82 41
7/8/2013 The 8-fold RXI version Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 83 Summary • Freeforms are specially useful when source, target or volumetric constrains are non- symmetric. • SMS method allows designing two freeforms to control very well extended sources via three wavefronts • It has direct application to demanding practical problems, as automotive headlamps, high CRI lamps and street lights Benitez, Miñano , Buljan, SMS freeforms for illumination OSA webinar, July 10, 2013 84 42
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