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Automotive lamps are essentially the optical transform devices. A light intensity angular distribution from a given light source (filament, HID arc, LED, etc.) is transformed to a desired new light intensity angular distribution namely beam pattern by means of an optical system such as a reflector or lens optics, or a projector module system. There are fundamentally five types of optical transformations occurring in a headlamp optical design: A). Light intensity angular distribution transforms from a light source to a beam pattern that is another fashion of angular distribution via a reflector-optics device. This transform device, sometimes, is referred to as the free-form reflector design; B). Light intensity angular distribution from a light source is transformed to a spatial distribution on a focal plane of an ellipsoidal (or similar) reflector; C).

The studies for headlamp optical design using current available and future projected white LEDs have been conducted. With desires of high performance and compact packaging sizes for both high and low beam headlamps, using LED light sources is a great challenge for the headlamp design optical engineers for light collecting efficiency, beam pattern compression and optical accuracy. Although total lumen flux produced by the LEDs may be comparable to the exiting light sources, e.g., incandescent bulbs, the optical and mechanical characteristics of LEDs may limit the headlamp applications. The paper identifies the etendue concerns and limitations for automotive headlamps when using LED light sources. It provides a guideline for considerations of using LEDs for automotive headlamp applications.

Design Sensitivity Analysis (DSA) is applied to a thermal data base for automotive lamps. The DSA predicts temperatures on lamps with dimensions and light sources different from those in the data base. Predicted temperatures closely agree with the measured temperatures. These predictions are done early in the design phase and allow use of a Cardinal thermal data base than a Conventional one. The DSA can also be used in designing lamps for thermal safety.

Condensation of water vapor in exterior automotive lamps may cause corrosion related performance problems and cosmetic concerns, particularly in clear lens lamps. The amount and distribution of the water vapor inside the lamp depends on the environment external to the vent, as well as lamp characteristics. In this paper we report laboratory investigations focusing on two basic factors affecting internal humidity; humidity outside of the vent opening and basic placement of the vent hole on the lamp.

Neon light sources offer unique challenges to the optical design of automotive lighting. When the tubular neon light source was first introduced, its luminous intensity distribution was assumed to be the same as other tubular sources, such as fluorescent tubes. However, upon investigation and analysis of measured data it became apparent that unlike fluorescents, neon tubes, as a volume source, provide a unique luminous intensity distribution instead of the familiar Lambertian distribution. This paper will develop an optical model for a tubular volume light source (neon tube), and further results will identify the effects of other optical elements, such as fluted lensing.

A design strategy for implementing High Intensity Discharge (HID) light sources in low beam head lamps with Free-Form Reflectors (FFRs) is presented. A theoretical analysis of a light source image formed by each portion of a reflector is presented as well as a strategy for using those images to create a head lamp beam pattern. Simulation results are shown for a head lamp design using this strategy.

Distributive lighting systems utilizing high intensity discharge (HID) light sources and optical fiber light pipes are capable of delivering a large luminous flux to head lamp assemblies. The challenge is to design an efficient lamp package that angularly distributes this flux to meet legal and customer requirements for head lamp photometry performance. In this communication we: 1) review photometry guidelines which make the design of die low beam lamp package challenging, 2) outline the basic relationships between the optical design parameters, 3) illustrate solutions to the design optimization problem with three low beam head lamp design approaches, and 4) present photometry results and a computer rendered road simulation for prototype distributive lighting low beam head lamp hardware.

A method of evaluating the uniformity of an illumination pattern of an automotive head lamp on a road surface is presented. The most critical area where the beam pattern uniformity can be identified is the high intensity region. In this area three parameters are used to evaluate beam pattern uniformity, correlation set, contrast level and relative intensity factor gradient. In a low intensity region of the illumination pattern, the same principle can be applied.

The use of Free-Form Reflector (FFR) technology allows the enhancement of performance in fog lamp design, especially where the figure of merit for performance is the sharpness of the cutoff line. However, traditional fog lamp bulbs with transverse filament orientations may not be the most desirable light source to take advantage of FFR technology. Axial filament orientations can have advantages over transverse filament orientations in the design of FFR fog lamps. Also, as front fog lamps have increasingly higher photometric performance levels, they exhibit an increased sensitivity to lamp misaiming and other detrimental lighting conditions. This paper will discuss high performance fog lamp design strategies using FFR technology and proper usage of front fog lamps.