Reducing Laser Speckle In Laser Based Metrology

Transcript

Reducing laser speckle in laser based metrology applications April 26, 2016 Mark Ventura, Vice President Sales & Marketing Optotune Switzerland AG | Bernstrasse 388 | CH-8953 Dietikon | Switzerland Phone +41 58 856 3011 | www.optotune.com | [email protected] Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 1 Company overview Electro-optical component provider Founded 2008 ~50 employees Sales partners in 27 countries HQ located in Zurich, Switzerland Privately owned 2 Optotune provides two core product lines Focus tunable lenses 3 Laser speckle reducers Speckle reduction principle: A moving diffuser is used to increase angular diversity Principle Local interferences Coherent laser Off On: >100Hz By moving a diffusor multiple speckle patterns are overlapped to reduce the perceived speckle noise 4 Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 5 Electroactive polymer based LSR • Diffuser motion made visible with stroboscopic lighting This video is available on www.optotune.com 6 Core technology: Electroactive polymers (EAPs) Voltage off Compliant electrodes t Voltage on p Deformation up to 20% V Advantages • • • • Applications Large deformation Energy efficient Silent Highly precise • • • • Robotics Pumps Valves Energy harvesting Optotune is first to apply EAPs in optics 7 Comparison of EAP-based LSR & spinning disk EAP-based LSR + Compact (1mm thickness possible, only a few mm added laterally) + Off-the-shelf component + 2D movement − Large size (circular disk & motor) + Long lifetime (no friction) + Well established technology + Light weight − Diffuser area on disk is factors larger than actually needed (expensive) + Vibration-free & silent − 1D angular movement − High voltage (300V, but low power) − Vibrations/noise − Only thin & light diffusors − Reliability issues due to mechanics − Limited in size (10mm CA) − Not suitable with elliptic diffusor − Polymer membrane cannot be AR coated 8 Spinning disk diffuser Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 9 New LSR based on reluctance force actuator Thin steel structure Low voltage AC current 10 Coil Diffuser of any material 1 𝐼2 𝑁 2 𝐹𝑅 = 𝜇0 𝐴 2 2 𝑑 Very high Q-factor allows for large amplitude at low power Q-factor: 2.94 1.6 1.4 Amplitude (mm) 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 11 50 100 Frequency (Hz) 150 200 Comparison reluctance force LSR & spinning disk Reluctance force LSR + Compact + Off-the-shelf component + Very large diffusers possible (HUD) + Well established technology + Long lifetime (no friction) − Large size (circular disk & motor) + Withstands harsh environments − Diffuser area on disk is factors larger than actually needed (expensive) + Low power (high Q-factor) 12 Spinning disk diffuser + Low cost − 1D angular movement − Some vibration might be transferred (depending on mechanical mount) − Not suitable with elliptic diffusor − Vibrations/noise − 1D linear movement (2D effect if 2 LSR are combined) − Reliability issues due to mechanics Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 13 Two typical metrology applications, where speckles reduce performance Structured lighting 14 Profiling with line lasers The issue of using diffusers • Diffuser acts as a large number of point sources, each with the NA of the diffuser angle LSR-3000 15  increase in etendue Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 16 Light engine for laser projection 17 Light engine for laser projection LSR Fiber Collimated laser source 18 Homogenizer Axicon Imaging optics DLP/ LCOS Projection optics Exemplary performance of a despeckled laser projection system (1/2) LSR off Camera settings: • F-stop: f/8 • Exposure: 1/20 sec • Focal length: 24 mm 20 LSR on Exemplary performance of a despeckled laser projection system (2/2) LSR off Camera settings: • F-stop: f/4.2 • Exposure: 1/20 sec • Focal length: 34 mm 21 LSR on Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 22 Speckle reduction on uniform laser line (compared to standard line with Powell lens) Conventional laser line with Powell lens (same laser source) Speckle free laser line with Optotune LSR Optotune LSR Collimated laser Oscillating cylindrical micro lenses 23 Static beam homogenizer Speckle reduction of a laser line Speckle reduction and homogeneity No LSR With LSR, not moving With LSR, moving • Speckle contrast S = 0.29 • Speckle contrast S = 0.45 • Speckle contrast S = 0.15 • Homogeneity ~10% • Larger speckle contrast due to periodicity of micro lenses • Homogeneity ~5% • Homogeneity ~10% 24 Speckle reduction by factor 2 possible Better homogeneity Speckle reduction of a laser line Line width No LSR With LSR, not moving With LSR, moving No significant increase of line width 25 Agenda • Introduction • Electroactive polymer based LSR • Reluctance force based LSR • Application examples  Light engine for laser projection  Line generation • Available products 26 Available standard products based on EAP technology LSR-3005 LSR-3010 LSR-5-17 LSR-10-22 Aperture 5 mm 10 mm 5 mm 10 mm Size (Ø or L x H) 41mm x 8.8mm 48mm x 8.8mm 17mm x 3.8mm 22mm x 3.8mm Standard diffuser angles* 6°, 12°, 17°, 24° Resonant frequency 300 Hz 180 Hz 300 Hz 180 Hz Oscillation amplitude 300 um 400 um 300 um 400 um Electronics Integrated, CE certified Integrated, CE certified Optional, not certified Optional, not certified * A variety of circular and elliptical diffusion angles available upon request 27 Overview & status of reluctance-force LSRs Picoprojector Line laser Desktop(µ-cylinder projector/ lens arrays) Laser TV Cinemaprojector HUD Diffuser [mm] 4.7x6.5 5x6 15x15 20x22 53x23 Aperture [mm] 4x5.5 5x5 12x12 18.5x18.5 50x20 Size [mm] 7x14x2 9.4x15.4x4 34x34x5 35x38x5 40x70x5 Oscillation 1D 1D 2x 1D 1D 2D Amplitude [um] 400 400 800 800 1000 Frequency [Hz] 400 300 150 120 >60 Status Alpha Beta Alpha Production Concept 28 Optotune – 1 slide Optotune Switzerland AG Bernstrasse 388 CH-8953 Dietikon Switzerland Phone: +41 58 856 3000 | Fax: +41 58 856 3001 www.optotune.com | [email protected]