EyeTrackVR-Docs/assets/getting_started_led_safety.md.7fccb842.js
2025-04-19 20:28:23 +00:00

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import{o as a,c as s,O as n}from"./chunks/framework.47aa8d5b.js";const o=JSON.parse('{"title":"","description":"","frontmatter":{},"headers":[],"relativePath":"getting_started/led_safety.md","filePath":"getting_started/led_safety.md","lastUpdated":1745094404000}'),t={name:"getting_started/led_safety.md"},p=Object.assign(t,{setup(r){return(l,e)=>(a(),s("div",null,e[0]||(e[0]=[n(`<h2 id="neareye-infrared-ir-emitter-safety" tabindex="-1">NearEye Infrared (IR) Emitter Safety <a class="header-anchor" href="#neareye-infrared-ir-emitter-safety" aria-label="Permalink to &quot;NearEye Infrared (IR) Emitter Safety&quot;"></a></h2><p><strong>Please exercise caution when messing around with IR emitters.</strong></p><p>Infrared emitters are invisible but <strong>not harmless</strong>. Excessive IR energy can heat the <strong>cornea</strong> and, over long exposures, contribute to cataract formation. At higher intensities and shorter wavelengths, the <strong>retina</strong> is also at risk due to focused thermal energy. This page explains how EyeTrackVR remains well below internationally accepted exposure limits, and how <em>you</em> can help ensure continued safety.</p><div class="danger custom-block"><p class="custom-block-title">DANGER</p><p><strong>DONOT</strong> remove currentlimiting resistors, supply the LEDs with a different voltage, substitute emitters, or bypass firmware current caps. These modifications invalidate the safety calculations and may cause <strong>permanent eye damage</strong>.</p></div><hr><h3 id="relevant-safety-limits" tabindex="-1">Relevant Safety Limits <a class="header-anchor" href="#relevant-safety-limits" aria-label="Permalink to &quot;Relevant Safety Limits&quot;"></a></h3><p>We design for compliance with these key international safety standards:</p><ul><li><strong>ICNIRP 2013</strong>: For exposures &gt;1000 seconds, the <strong>anterior eye</strong> (cornea and lens) irradiance limit is<br><strong>10mW/cm²</strong> (equivalent to 100W/m²).</li><li><strong>IEC 62471</strong> and <strong>IEC 60825-1</strong>: For sources in the <strong>retinal hazard region</strong> (4001400nm), and a worst-case exposure of ≥10s, the irradiance limit is<br><strong>4mW/cm²</strong> (averaged over a 7mm pupil projected cone of 11mrad).</li></ul><p>EyeTrackVR emitters operate at <strong>850nm</strong>, within the retinal hazard region.<br> Our calculated output is well below both thresholds:<br><strong>≤0.8mW/cm²</strong> at 1cm — <strong>5×</strong> below the retinal limit, <strong>13×</strong> below the corneal limit.</p><hr><h3 id="why-current-ma-isn-t-enough" tabindex="-1">Why Current (mA) Isnt Enough <a class="header-anchor" href="#why-current-ma-isn-t-enough" aria-label="Permalink to &quot;Why Current (mA) Isnt Enough&quot;"></a></h3><p>LED current (mA) is not a direct measure of safety. <strong>Irradiance</strong> (power per unit area) determines actual eye exposure:</p><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Irradiance E = Radiant Intensity Ie / Illuminated Area A</span></span>
<span class="line"><span style="color:#babed8;">A = r² · Ω where Ω = 2π(1cosθ)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><ul><li><em>Ie</em> = radiant intensity (in <strong>mW/sr</strong>, from datasheet)</li><li><em>r</em> = distance from LED to cornea (worst-case 1cm)</li><li><em>θ</em> = half-angle of LED emission cone (datasheet: 60°, full angle 120°)</li><li><em>Ω</em> = solid angle in <strong>steradians</strong><br> (for θ = 60° → Ω ≈ πsr)<br> → A = πcm² at 1cm</li></ul><hr><h2 id="hardware-exposure-calculations" tabindex="-1">Hardware Exposure Calculations <a class="header-anchor" href="#hardware-exposure-calculations" aria-label="Permalink to &quot;Hardware Exposure Calculations&quot;"></a></h2><h3 id="led-xl3216hirc850" tabindex="-1">LED: XL3216HIRC850 <a class="header-anchor" href="#led-xl3216hirc850" aria-label="Permalink to &quot;LED: XL3216HIRC850&quot;"></a></h3><table><thead><tr><th>Datasheet Value</th><th>Symbol</th><th>Notes</th></tr></thead><tbody><tr><td>Radiant intensity @ 20mA</td><td><em>Ie₍20ₘₐ₎</em> = 5mW/sr</td><td>Typical max value, 60° half-angle</td></tr><tr><td>Full emission angle</td><td>120°</td><td>⇒ θ = 60°, Ω ≈ πsr</td></tr></tbody></table><p>Radiant intensity scales roughly linearly with current:</p><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Ie = Ie₍20ₘₐ₎ × (I_drive / 20mA)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br></div></div><hr><h3 id="v3-module-2-leds-3-2-ma-each" tabindex="-1">V3 Module (2 LEDs @ 3.2mA each) <a class="header-anchor" href="#v3-module-2-leds-3-2-ma-each" aria-label="Permalink to &quot;V3 Module (2 LEDs @ 3.2mA each)&quot;"></a></h3><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Ie_single = 5 × (3.2 / 20) = 0.80mW/sr</span></span>
<span class="line"><span style="color:#babed8;">E_single = 0.80 / π = 0.25mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">E_total = 0.25 × 2 = 0.51mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">→ ~5% of ICNIRP corneal limit</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><hr><h3 id="v4-module-4-leds-2-4-ma-each" tabindex="-1">V4 Module (4 LEDs @ 2.4mA each) <a class="header-anchor" href="#v4-module-4-leds-2-4-ma-each" aria-label="Permalink to &quot;V4 Module (4 LEDs @ 2.4mA each)&quot;"></a></h3><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Ie_single = 5 × (2.4 / 20) = 0.60mW/sr</span></span>
<span class="line"><span style="color:#babed8;">E_single = 0.60 / π = 0.19mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">E_total = 0.19 × 4 = 0.76mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">→ ~8% of ICNIRP corneal limit</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><hr><h3 id="worst-case-high-bin-calculations" tabindex="-1">Worst-Case (High Bin) Calculations <a class="header-anchor" href="#worst-case-high-bin-calculations" aria-label="Permalink to &quot;Worst-Case (High Bin) Calculations&quot;"></a></h3><p>Some LEDs may fall into a higher output bin with up to <strong>8mW/sr @ 20mA</strong>. We conservatively recalculate:</p><h4 id="v3-max-bin-2-leds-3-2-ma" tabindex="-1">V3 Max Bin (2 LEDs @ 3.2mA): <a class="header-anchor" href="#v3-max-bin-2-leds-3-2-ma" aria-label="Permalink to &quot;V3 Max Bin (2 LEDs @ 3.2mA):&quot;"></a></h4><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Ie_single = 8 × (3.2 / 20) = 1.28mW/sr</span></span>
<span class="line"><span style="color:#babed8;">E_single = 1.28 / π = 0.41mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">E_total = 0.41 × 2 = 0.81mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">→ ~8.1% of ICNIRP corneal limit</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><h4 id="v4-max-bin-4-leds-2-4-ma" tabindex="-1">V4 Max Bin (4 LEDs @ 2.4mA): <a class="header-anchor" href="#v4-max-bin-4-leds-2-4-ma" aria-label="Permalink to &quot;V4 Max Bin (4 LEDs @ 2.4mA):&quot;"></a></h4><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Ie_single = 8 × (2.4 / 20) = 0.96mW/sr</span></span>
<span class="line"><span style="color:#babed8;">E_single = 0.96 / π = 0.31mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">E_total = 0.31 × 4 = 1.22mW/cm²</span></span>
<span class="line"><span style="color:#babed8;">→ ~12.2% of ICNIRP corneal limit</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><hr><h2 id="your-responsibilities" tabindex="-1">Your Responsibilities <a class="header-anchor" href="#your-responsibilities" aria-label="Permalink to &quot;Your Responsibilities&quot;"></a></h2><ol><li><strong>Do not modify the hardware.</strong> Changing components or resistors voids all safety guarantees.</li><li><strong>Verify functionality before use.</strong> Use an IR-sensitive camera to confirm all LEDs are on and of equal brightness.</li><li><strong>Perform periodic inspections</strong> to ensure IR emitters have not damaged and remain equal brightness.</li></ol><hr><h2 id="appendix-a--formula-summary" tabindex="-1">Appendix A Formula Summary <a class="header-anchor" href="#appendix-a--formula-summary" aria-label="Permalink to &quot;Appendix A Formula Summary&quot;"></a></h2><div class="language- line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki material-theme-palenight"><code><span class="line"><span style="color:#babed8;">Ω = 2π(1cosθ) (solid angle of emission)</span></span>
<span class="line"><span style="color:#babed8;">A = Ω × r² (illuminated area)</span></span>
<span class="line"><span style="color:#babed8;">Ie = Ie₍20ₘₐ₎ × I / 20mA</span></span>
<span class="line"><span style="color:#babed8;">E (per LED) = Ie / A</span></span>
<span class="line"><span style="color:#babed8;">E_total = E × (# of LEDs)</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><hr><h2 id="appendix-b--quoted-guideline-icnirp-2013" tabindex="-1">Appendix B Quoted Guideline (ICNIRP 2013) <a class="header-anchor" href="#appendix-b--quoted-guideline-icnirp-2013" aria-label="Permalink to &quot;Appendix B Quoted Guideline (ICNIRP 2013)&quot;"></a></h2><blockquote><p>“To avoid thermal injury of the cornea and possible delayed effects on the lens of the eye (cataractogenesis), infrared radiation (780nm &lt; λ &lt; 3µm) should be limited to 100Wm⁻² (10mWcm⁻²) for lengthy exposures (&gt;1000s).”</p></blockquote><blockquote><p>— <em>ICNIRP Guidelines on Limits of Exposure to Incoherent Optical Radiation (2013)</em><br> PDF: <code>/public/safety/ICNIRP_optical_radiation.pdf</code></p></blockquote><hr><p>If you have suggestions, believe these calculations are inaccurate, or wish to contribute improvements, please <a href="https://github.com/EyeTrackVR/EyetrackVR-Docs" target="_blank" rel="noreferrer">open a discussion on GitHub</a>. Your feedback helps us keep everyone safe.</p>`,45)])))}});export{o as __pageData,p as default};