How a LED Projector Lens Works
Projectors let you relive moments like wedding videos on the big screen, and create a theater-like experience at home. They also have the potential to save on energy costs compared to lamp-based alternatives.
A great LED lens does one primary job-it produces enough light to comply with road safety requirements. It must be bright enough to provide adequate illumination, while also producing a well-formed light pattern that is not annoying to other road users.
Optical Design
A projector lens is essential for delivering intense light in an organized and tightly controlled beam pattern. Projector lenses are used in the automotive industry and in many other applications to led projector lens create two-dimensional images on screens. They are also found in places like movie theaters and planetariums to project images on large surfaces without sacrificing image quality.
A led projector lens uses several optical designs to collect and refocus light to create a specific beam pattern. These optical design elements include a lens and a reflector bowl. A reflector bowl is made of a reflective material such as aluminum alloy to keep heat from the lens and allow it to operate at higher temperatures. A lens is a curved piece of plastic or glass that helps to shape the light produced by the LED.
Using advanced optical design software like Zemax, Greenlight engineers create world class imaging and illumination optics. They are experts in the use of spherical and aspheric lenses to minimize element count and size while achieving high resolution and performance requirements. They are skilled at utilizing freeform lenses as well to provide unique solutions for their customers.
LEDs offer a number of benefits over traditional HID and laser pumped phosphor (LaPh) sources, such as high lumens, low power consumption, and long lifetimes. However, there are challenges to overcome for LEDs in TI DLP projectors. This paper explains some of the system options and illumination optical design challenges when using LEDs as the primary source of light for DLP projectors.
Light Collection Optics
The light collection optics are usually made of two lens elements, a first one being smaller with a spherical shape and the second larger and having a spherical or aspheric surface. The first one collects the emitted radiation from the LED and directs it to the collimator, where the rays are then concentrated. It is important that the emitted radiation from the LED is directed to a large surface area, as this helps achieve high brightness and good optical performance.
The spherical or aspheric shape of the second lens allows the rays to be reflected from the surface. In this way, a significant portion of the emitted radiation is collected in the collimator, which leads to an effective increase in the brightness of the LED. The spherical or aspheric design also makes it possible to achieve better optical efficiency by avoiding surface losses.
In addition, the second lens is designed to allow a small fraction of the radiation emitted by the LED to overlap with the rays of the light collection optical system. This makes it easy to control the emission intensity of the LED so that the brightness of the LED does not exceed a predetermined limit.
The Aozoom Bi-LED Lens projector is a trending lighting upgrade part used by more and more motor-vehicle users to replace their stock halogen or xenon front headlights. It aims to produce sufficient lighting that conforms to road safety rules, while ensuring that it is not too bright or glaring to harm other vehicle users. The product has passed strict product testing and inspection and has been approved by a number of automotive aftermarket modification shops and manufacturers.
Collimator Optics
Collimator optics are designed to efficiently collect light emitted from LEDs by limiting their half cone angle of emission. They are typically small spherical glass elements to provide a high index of refraction and avoid softening or melting of plastic optics in close proximity to the high brightness LEDs. This design also helps to limit the amount of heat the collimator must absorb while working with the high intensity LEDs.
The LEDs are oriented with their illumination plane substantially parallel to the collimator cutting plane. This arrangement allows the LED’s to illuminate a large area of the target plate while maintaining an even and consistent illumination of that surface. The illumination is uniformly diffused over a range of angles that will fully fill the entrance pupil of the projection lens assembly but minimizes any out-of-pupil illumination that does not contribute to a useful test pattern on the target plate.
The focusing mechanism for the LED collimator comprises a target plate frame 31, a holographic diffuser plate, and a projection lens assembly. A precision alignment mechanism is provided to position and align the target plate frame 31 and led projector lens the holographic diffuser plate so that their front surfaces (the ones that face the projection lens assembly) are aligned with each other over the entire field of view of the projection lens. A minimum of three precision adjustments are used to achieve this alignment.
Red LED
LEDs are designed to emit a focused beam of light at a certain wavelength. The wavelength can be either visible or invisible depending on the type of LED and its circuitry. This is because a LED contains a photosensitive material that can be excited to different brightnesses by a specific sequence of pulses. This enables the LED to be controlled and synchronized with the video display screen.
LED technology allows for a much more compact and efficient projector optical system. The combination of LED illumination with single chip DLP projection technology also produces more vibrant and vivid color images. The color gamut of a LED is broader than the range of a halogen or HID light source. This can be a benefit for some design applications where the image size is limiting.
The most common LED projectors use what are called 3LED light sources. The 3LED design uses individual LED lights for each of the primary colors in the RGB color system: red, green and blue. These are then combined with some variation to construct the entire projected image.
However, the LEDs used in the red channel have not yet reached the level of performance needed for many product designs. To address this issue, the LTRPHP3W model adds a deep blue LED to illuminate the top side of the phosphor coated converted green LED illuminator. This enables more of the green LED flux to be usable when color balanced for typical projector white points and improves the red LED output in terms of both brightness and color saturation.
