1 / 49

LIPA Laserama Topics on Laser Illuminated Projectors

LIPA Laserama Topics on Laser Illuminated Projectors. February 19, 2014. LIPA Membership. Today’s Agenda. Regulatory Update: Are they legal? Radiance is the same – lamps and laser projectors IEC standards updates Understanding speckle … and how to measure it

cera
Download Presentation

LIPA Laserama Topics on Laser Illuminated Projectors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LIPA LaseramaTopics on Laser Illuminated Projectors February 19, 2014

  2. LIPA Membership Contact LIPA at info@lipainfo.org

  3. Today’s Agenda Regulatory Update: Are they legal? • Radiance is the same – lamps and laser projectors • IEC standards updates Understanding speckle • …and how to measure it Laser Color Primary Selection • Impacts on Gamut, Image Quality and Efficiency Do you see what I see? • Color Matching and the Single Observer Any Questions? Contact LIPA at info@lipainfo.org

  4. LIP light output = Lamp projector light output Pete Ludé Mission Rock Digital, LLC pete@MissionRockDigital.com Regulatory update

  5. Study conducted • LIPA Commissioned Study: Tested optical characteristics of • 35mm film projector • Current Xenon short-arc digital cinema projectors • Prototype laser projectors • Lead Researcher: Dr. David Sliney • Casey Stack, Laser Compliance • Jay Parkinson, Phoenix Laser Safety • David Schnuelle, Dolby Laboratories • Eight projectors tested in various locations over 7 months. Contact LIPA at info@lipainfo.org 5

  6. Hot off the press! • Published in Health Physics, March 2014 • Radiation Safety Journal • Official Journal of the Health Physics Society • Peer review complete • Cover story! Additional analysis presented at Society of Motion Picture & Television Engineers Conference – October 22, 2013. Contact LIPA at info@lipainfo.org

  7. LARGE FOCAL SPOT (FILAMENT IMAGE) MICROSCOPIC FOCAL SPOT (“DIFFRACTION LIMITED”) Laser Brightness (Radiance) LENS LASER LENS From Sliney DH and Trokel, S, 1993 Contact LIPA at info@lipainfo.org

  8. Comparison of Radiance Values Contact LIPA at info@lipainfo.org

  9. Comparing Radiance: Lamp vs. Laser Normalized Measured Radiance (W • cm-2 • sr-1) Laser Laser Laser Xenon Xenon 2,000 30,000 Actual Luminance Power (Lumens): 55,000 17,000 5,000 5,000 5,000 Normalized Luminance Pwr (Lumens): 5,000 5,000 5,000 Contact LIPA at info@lipainfo.org

  10. Conclusion Traditional lamp projectors and new laser-illuminated projectors, when of equal luminance power, emit almost identical radiance. Contact LIPA at info@lipainfo.org 10

  11. IEC Regulatory Changes

  12. Laser Projector Regulation under IEC All laser product requirements are defined in 60825 • Medical • Industrial • Laboratory use • Laser Welding • Laser Illuminated Projectors IEC 60825-1 Ed 2 (2007) Safety of Laser Products Part 1: Equipment classification & Requirements Contact LIPA at info@lipainfo.org

  13. Laser Projector Regulation under IEC IEC 62471 Ed 1 (2006) Photobiological safety of lamps and lamp systems IEC 60825-1 Ed 3 (2014) Safety of Laser Products Part 1: Equipment classification & Requirements Carve-out for devices with radiance < (1 MW•m-2 •sr-1)/α Contact LIPA at info@lipainfo.org

  14. Laser Projector Regulation under IEC IEC 60825-1 Ed 3 (2014) Safety of Laser Products Part 1: Equipment classification & Requirements IEC 62471-5 Ed 1 (2015?) Photobiological safety of Lamp Systems for Image Projectors Contact LIPA at info@lipainfo.org

  15. WA ND ME MT MN OR ID VT NH WI SD MA NY CT WY RI MI PA OA NB NJ NV OH MD IN DE IL UT WV CO CA VA KS MO KY NC TN AZ OK NM SC AR GA MS AL LA TX FL 0 500 Miles 0 500 Km 500 Miles 0 0 500 KM US State Laser Regulations No relevant laser regulations Some relevant laser regulations Most involved & potentially burdensome Contact LIPA at info@lipainfo.org AK HI 0 100 Miles 0 100 Km

  16. Speckle

  17. What is Speckle? Interference pattern that occurs when coherent light is scattered off an optically rough surface (i.e. screen) Visible noise on uniform areas of scene • Decreases perceived contrast • Most visible on uniform, bright scene elements (e.g. sky) • More visible when you move your head back and forth (“subjective” speckle) Figure of merit: Speckle contrast ratio Source: K.O. Apeland (5) SCR= standard deviation / mean intensity in % • Between 0 and 1 • 0 means “no speckle” • Can be expressed as percentage Source: Goodman (8), Curtis (7) Contact LIPA at info@lipainfo.org

  18. Methods to reduce speckle In Theory: • Polarization diversity • Temporal averaging • Wavelength diversity • Angle diversity • Temporal coherence reduction • Spatial coherence reduction In Practice: Array of multiple emitters • Slightly different frequencies (wavelength diversity) • Spatially separated (angle diversity) Rotating diffusers Vibrating diffusers Hadamard matrices Vibrating screen Other methods… Source: Goodman (8) Contact LIPA at info@lipainfo.org

  19. Speckle Metrology Considerations Source (Laser) • Projector Focal plane (≠ screen?) • Reference light source (coherent) • Luminance power (brightness) Contact LIPA at info@lipainfo.org

  20. Speckle Metrology Considerations Source (Laser) • Projector Focal plane (≠ screen?) • Reference light source (coherent) • Luminance power (brightness) Camera • Clear aperture / f-number • Pixel size (relative to speckle size) • Focal length (related to distance) • Shutter speed / Integration time • Focus point (= screen?) • Spectral filtering (high/low-pass) Contact LIPA at info@lipainfo.org

  21. Speckle Metrology Considerations Source (Laser) • Projector Focal plane (≠ screen?) • Reference light source (coherent) • Luminance power (brightness) Camera • Clear aperture / f-number • Pixel size (relative to speckle size) • Focal length (related to distance) • Shutter speed / Integration time • Focus point (= screen?) • Spectral filtering (high/low-pass) Image Processing • Gamma (Optical-Electrical transfer curve) • Exposure • Compression algorithm • Bit depth / dynamic range Digital Image Processing Contact LIPA at info@lipainfo.org

  22. Speckle Metrology Considerations Source (Laser) • Projector Focal plane (≠ screen?) • Reference light source (coherent) • Luminance power (brightness) Camera • Clear aperture / f-number • Pixel size (relative to speckle size) • Focal length (related to distance) • Shutter speed / Integration time • Focus point (= screen?) • Spectral filtering (high/low-pass) Image Processing • Gamma (Optical-Electrical transfer curve) • Exposure • Compression algorithm • Bit depth / dynamic range Digital Image Processing Screen • Screen gain • Total Integrated Scatter • Objective (second) screen Contact LIPA at info@lipainfo.org

  23. Speckle Metrology Considerations Source (Laser) • Projector Focal plane (≠ screen?) • Reference light source (coherent) • Luminance power (brightness) Camera • Clear aperture / f-number • Pixel size (relative to speckle size) • Focal length (related to distance) • Shutter speed / Integration time • Focus point (= screen?) • Spectral filtering (high/low-pass) Image Processing • Gamma (Optical-Electrical transfer curve) • Exposure • Compression algorithm • Bit depth / dynamic range Digital Image Processing Screen • Screen gain • Total Integrated Scatter • Objective (second) screen Room Geometry and Environment • Projection and camera capture angles • Viewing distance / Ambient light • Ratio of image area to average speckle size Contact LIPA at info@lipainfo.org

  24. To learn more… Technology Summit on Cinema at NAB April 5-6, 2014 Las Vegas Convention Center https://www.smpte.org/tsc2014 LIPA Speckle Metrology Working Group Update report at: Contact LIPA at info@lipainfo.org

  25. Laser Color Primary Selection Options and Tradeoffs • Impacts on Gamut, Image Quality and Efficiency Bill Beck BTM Consulting, LLC • billbeck59A2@mac.com • +1 617.290.3861

  26. Primary Selection: Lumens vs. Watts 545 nm, 669 lm/W 532 nm, 603 lm/W 618 nm, 277 lm/W 462 nm, 45 lm/W 445 nm, 20 lm/W 640 nm, 120 lm/W February 19, 2014 Bill Beck BTM Consulting, LLC

  27. First Pass Observations… “Infinite” number of RGB combinations and “Spectral Power Distributions” (SPD) to achieve desired gamut, white-point and primaries - requires design TRADEOFFS Desired color-space can be produced with native RGB wavelengths and balance delivered from the laser engine… …or via color correction in the projector, which always reduces overall brightness and sometimes bit depth Likely ideal solution will be a bit of both Contact LIPA at info@lipainfo.org

  28. Single line vs. Multi/Wide-band Primaries • Narrow band RGB laser “lines” FWHM ≤ 1 nm • Simple modeling and supply chain … but • Massive Speckle • Potential for “Observer Metameric Failure” (OMF) • Multiple RGB lines per primary - n x FWHM ≤ 1 nm • Wavelength options depend on physics and availability • Little impact on speckle if narrowband • Unknown impact on OMF • Spectrally broadened RGB bands FWHM 10 - 40 nm • Replicates incoherent white light • Low speckle and OMF • Hard to achieve with available lasers Contact LIPA at info@lipainfo.org

  29. Single line vs. Wide-band Primaries Wide, “filled in” primary bands are ideal but… Very difficult to procure laser sources • At the right wavelengths • Fill in the bands of interest • Exhibit the same good beam quality, i.e., low étendue • Have similar lifetimes …all, at a reasonable cost Let’s look at the tradeoffs Contact LIPA at info@lipainfo.org

  30. Primary Selection vs. Gamut • Rec 709 • DCI P3 • Rec 2020 • Narrowband primaries “on locus” • Wider gamut and more saturated • But higher speckle and OMF • Longer Reds and shorter Blues are commercially available • Shorter Green adds Magenta but cuts Yellow saturation • Wider gamut primaries reduce luminous efficacy (lm/watt) Contact LIPA at info@lipainfo.org

  31. Primary selection vs. Speckle Contrast Ratio (SCR) Benchmark is Xenon illumination – Incoherent and Lambertian • RGB pass bands for DCinema installed base ~60 nm wide • System f# ~2.4 (fast) to maximize angle and usable lamp output • SCR for Xenon ~ 1% - hard to measure Single wavelength, narrow line (≤1 nm) RGB primaries SCR ~20% • UNWATCHABLE in Green and Red; speckle noticeable even in Blue Multiple emitters of the same wavelength – little reduction in SCR Multiple beamlines that “fill” 10 - 40 nm reduce speckle to Xenon levels ***Each Laser Primary should fill 10 – 40 nm band*** Contact LIPA at info@lipainfo.org

  32. Primary Selection vs. Observer Metameric Failure (OMF) Three factors to consider: • Spectral Bandwidth of each primary • Spectral Power Distribution (SPD) i.e., flat vs. peaky • Color point of primary (wavelength or x,y) Bandwidth is first order – wider is better for OMF and Speckle • Smooth SPD is better than peaky • Wide band primaries reduces saturation and gamut slightly Wavelength is important, especially for narrow band primaries • Intersection with the tri-stimulus curves determines impact • More work is needed here – computational and observational See: Wiley Periodicals Vol. 34, Number 5, October 2009 Rajeev Ramananth Contact LIPA at info@lipainfo.org

  33. Primary Selection vs. Luminous Efficacy Luminous Efficacy = White balanced lumens / RGB watt Ideal is to use “native” laser primaries: • Rec 709 : 613/550/463 nm = 362 lm/W • DCI P3 : 618/545/462 nm = 366 lm/W • Rec 2020 : 630/532/467 nm = 288 lm/W Readily available lasers: 640/532/445 nm • Rec 709 : Raw 249 lm/W Correction reduces lm/W • DCI P3 : Raw 261 lm/W Correction reduces lm/W • Rec 2020 : Raw 261 lm/W Very slight reduction in lm/W Contact LIPA at info@lipainfo.org

  34. Primary Selection vs. Wall Plug Efficiency (WPE) Projector + Engine WPE is a very complex function of: RGB wavelengths – sets luminous efficacy (200 - 350 lm/RGB watt) Étendue at the PJ input – determines PJ throughput Aggregation and delivery efficiency – set gross RGB watts required Laser Device WPE – drives engine efficiency and cooling required • Ranges from 3% for some Greens to >30% short Blue Laser Source Speckle Contrast Ratio – if low, no additional losses in projector for downstream speckle reduction Contact LIPA at info@lipainfo.org

  35. Current Laser Primary Options For reference ~ 85,000 RGB lm input to the projector for 30,000 lm output VCSEL=Vertical Cavity Surface Emitting Laser SHG=Second Harmonic Generation DPSS=Diode Pumped Solid State FL=Fiber Laser Contact LIPA at info@lipainfo.org

  36. A few words on Optical Fiber Delivery Watts / beamline and beam quality determine the number and size of fibers required Best case: high power per color - with some redundancy • Fewest fibers per kilo-lumen on screen • Smallest diameter (cheapest) fibers Worst case: lots of low power devices with bad beam quality • Requires large number of large diameter fibers • Cable ends up too big, too stiff and too expensive Don’t worry about the fibers • Single fiber cables can deliver kilowattsof laser power • Attenuation is very low - up to 100 meters or more Contact LIPA at info@lipainfo.org

  37. Summary and Conclusions Primary wavelengths + BW impact: • Gamut, Speckle, Observer Metameric Failure (OMF), Luminous Efficacy (LE), Wall Plug Efficiency (WPE) Wide band primaries, where possible, reduce speckle and OMF • Difficult to achieve in practice • Slight tradeoff with saturation and gamut (smaller triangle) Wide Gamut laser options are available, but less efficient than DCI P3 Optimum primary wavelengths and bandwidths do no coincide with mature,low cost laser offerings, especially for Green and Red • RED: too long and narrow; high speckle and low lm/W • GREEN: is too narrow; high speckle and low electrical efficiency • BLUE: can fill the bandat low cost but power per device is still low Contact LIPA at info@lipainfo.org

  38. Do you see what I see? Color Matching and the Single Observer Matt Cowan Entertainment Technology Canada Ltd. matt@kermis.com

  39. Metamerism Metamerism is the matching of apparent colour of objects with different spectral power distributions. Colors that match this way are called metamers. (wikipedia) Observer metameric failure can occur because of differences in colour vision between observers. …….. In all cases, the proportion of long-wavelength-sensitive cones to medium-wavelength-sensitive cones in the retina, the profile of light sensitivity in each type of cone, and the amount of yellowing in the lens and macular pigment of the eye, differs from one person to the next. This alters the relative importance of different wavelengths in a spectral power distribution to each observer's colour perception. As a result, two spectrally dissimilar lights or surfaces may produce a colour match for one observer but fail to match when viewed by a second observer. (Wikipedia) Contact LIPA at info@lipainfo.org

  40. Raises 2 Issues With color science we should be able to calculate different spectral distributions that give an exact “average” color match. (Metamers) The population of observers will have differing sensitivity to the degree of the average match. (Observer Metameric Failure) Contact LIPA at info@lipainfo.org

  41. What we see, What we measure(100 years of color science in 1 slide) Metrics established through: • Deriving observer’s sensitivity to color through Cone Sensitivity Functions • Choosing a representative observer as the “standard observer” • Transforming cone functions to “color matching functions” (CMF) • Determining spectral power distribution (SPD) of stimulus • Integrating the SPD across the CMF to achieve 3 numbers (X,Y,Z) to describe the stimulus color • Normalize the X,Y,Z values to achieve the familiar x,y,L coordinates XYZ x,y,L CMF SPD Contact LIPA at info@lipainfo.org

  42. Color Matching Functions Cone functions are basic HVS characteristic CMF is linear transform of cone functions CIE 1931 Color matching functions Contact LIPA at info@lipainfo.org

  43. The Real World – we are all different Standard – singular response Figure 3: Cone spectral responses for 1000 simulated individual observers randomly sampled from the Tl, Tm, L, M, and S values of Equation 1 (Fairchild et al 2013). (Plot is 1000 narrow lines on same plot) Contact LIPA at info@lipainfo.org

  44. Standard Observer – did we get it right in 1931? Contact LIPA at info@lipainfo.org

  45. Try a Different CMF – fix offset Offset is failure of 1931 CMF. Scatter is observer metamerism From Sony white paper “Color Matching between OLED and CRT” v1.0 Feb 15, 2013 Contact LIPA at info@lipainfo.org

  46. Observer Metamerism failure How significant is differences in observers? Occurs with all illuminations – even daylight Contact LIPA at info@lipainfo.org

  47. Figure 7: The metameric pairs for each of the 24 XRiteColor Checker patches as seen by the standard observer on the left and the 95th percentile simulated observer on the right. (Fairchild et al 2013) Contact LIPA at info@lipainfo.org

  48. Conclusions Color matching using instruments will be better if we use CMF’s updated from 1931 Observer Metamerism failure is a fact of nature, we live with it every day Contact LIPA at info@lipainfo.org

  49. www.LIPAinfo.org LIPA LaseramaQuestions?? Pete Ludé Mission Rock Digital, LLC pete@MissionRockDigital.com • Bill Beck • BTM Consulting, LLC • billbeck59A2@mac.com • +1 617.290.3861 Matt Cowan Entertainment Technology Canada Ltd. matt@kermis.com

More Related