某公司光學(xué)基礎(chǔ)培訓(xùn)資料_圖文

1、Outline 1. 2. 3. 4. 5. 6. Lighting fundamentals Photometry types Optic types / styles Molding / manufacturing considerations Frequently Asked Questions Summary 2 1. Lighting Fundamentals Etendue Reflection Refraction Total internal reflection Fresnel losses 3 Etendue Etendue is a French term that tr

2、anslates to “extent” or “space”. This is also called the Lagrange Invariant or sometimes the Invariant. This concept is directly from the 2nd law of thermodynamics (conservation of energy. Etendue is a fundamental limit in optical physics that cannot be broken. Every optical system has a first order

3、 numerical value that is an invariant. The simple approximated form of Etendue is: Etendue = area * solid angle 4 Etendue Example A simple square LED and lens are used here to illustrate Etendue. AREAoptic SAsource Source SAoptic AREAsource Optic 5 Etendue Example The source and optic Etendue will b

4、e computed separately and then the ratio taken to understand the expected flux transfer efficiency. Again, the basic equation for Etendue is: AREA * Solid Angle (SA Assume: AREAsource = 1 x 1mm = 1mm2 SAsource = * sin(120/22 = 2.36 sr AREAoptic = * (12.7mm/22 = 126.7mm 2 SAoptic = * sin(10/22 = 0.02

5、 sr 6 Etendue Example ETENDUEsource = AREAsource * SAsource = 2.4 ETENDUEoptic = AREAoptic * SAoptic = 3.0 ETENDUEefficiency = ETENDUEoptic / ETENDUEsource = 128% This system is not limited by Etendue for flux transfer. Other factors such as collection efficiency, absorption loss, etc. will degrade

6、the flux transfer. 7 Reflection Reflection: Return of radiation by a surface, without change in wavelength. The reflection may be specular, from a smooth surface; diffuse, from a rough surface or from within the specimen; or mixed, a combination of the two. 8 Refraction Refraction: The bending of in

7、cident rays as they pass from a medium having one refractive index (N into a medium with a different refractive index (N. 9 Total Internal Reflection (TIR Total Internal Reflection (TIR: The reflection that occurs within a substance because the angle of incidence of light striking the boundary surfa

8、ce is in excess of the critical angle. 10 Fresnel Losses Fresnel Losses: When light moves from a medium of one refractive index to another, both reflection and refraction of the light may occur. A loss of transmission that occurs at the interface is caused by this Fresnel reflection 11 Fresnel Losse

9、s 12 2. Photometry Types Type A photometry is used for automotive lighting specifications. Type B photometry is used in architectural lighting. Type C is used in architectural lighting and is the most common form for architectural lighting data. Type A and B are very similar for smaller angles (less

10、 than 20 degrees and points within a few degrees of either axes. 13 3. Optic Types / Styles Fresnel Lens Lenses Lightpipes Reflectors Courtesy of Breault Research Organization Diffusers TIR Optics 15 The unmanaged light is desired for flashlight (torchray is directed to edge of outersurfaceParabolic

11、 or ellipticalshape to direct light Collimating Lens in front of LED Although for the illumination * Common to both warm and cool white LEDs“Frankie”Highlights: CCTFrankenstein Cool White - 6000KHypothetical LED Characteristics Unit Min Typ MaxThermal Resistance, junction to solder pointC/W10Viewing

12、 Angle (FWHM132Temperature coefficient of voltage mV/C-3.0DC Forward Current mA1000DC Pulse Current A 2.5Forward Voltage at 350mA V 2.9 3.4 3.8Forward Voltage at 700mA V 3.2 3.6 4.1Forward Voltage at 1000mA V 3.4 3.7 4.4LED Junction TemperatureC140 Luminous Flux at 350mA lumens92100108Frankenstein Warm White - 3000KHypothetical LED Characteristics Unit Min Typ MaxThermal Resistance, junction to solder point?C/W10Viewing Angle (FWHM132Temperature coefficient of voltage mV/?C-3.0DC Forward Current mA700DC Pulse Current A 2.5Forward Voltage at 350mA V 2.9 3.4 3.8Forward Voltage at 700mA V 3.2