LED Projector Lenses
LED projector lenses focus intense light into a tight, well-organized beam pattern. This is important so that you can see where you’re going while driving on highways or country roads.
The dual-core bi-led lens is the new design that improves brightness in both low and high beams. It also eliminates glare to oncoming traffic.
Light Collection Optics for LEDs
LED lights generate a lot of light. While this is good for illuminating a large area, it can also be dangerously distracting. To make sure that only the light you want to see is emitted, LEDs often use secondary optics like lenses or reflectors to focus and magnify the LED lighting. The primary function of an LED lens is to collect light from the diode and focus it into a tighter pattern. This allows the light to be used more effectively.
The most efficient LEDs are useless without the right LED optics. An incorrectly matched secondary optic can cause an LED to lose up to 70 percent of its light. For this reason, the LED industry has developed a number of different types of optics for LED lighting.
For example, if you need to warn or attract people from a side angle, TIR designed LEDs are your best bet. These optics are molded from specular polymers and can be applied to the surface of an LED reflector to control its spread. Another type of LED optic is the pillow lens, which is a plastic that surrounds the entire LED chip. This helps to contain the light and is a good choice for low-light applications where the LEDs are not visible. Unlike the TIR lens, which clips securely into the LED star board, the pillow lens needs to be externally adhered to it.
Two Lens Transmissive Collimator
The optical performance of the proposed double freeform lens was evaluated by means of Zemax simulations. The analysis commenced by determining the collimating performance of the lens given the radiation intensity pattern for the NCSU276A UV-LED used in the simulations (see Figure 2a,b).
The two surface profiles of the designed freeform lens were characterized mathematically using polar coordinates. The resulting two functions were used to independently assign the surfaces S1 and S2 different roles. The function of S1 was to refract all light rays emitted from the point source S in such a way that they appear to originate from a new imaginary point source S’ located at a distance ro from the LED (see Figure 1a,b).
S2’s role was to collimate these redirected rays onto the detector plane. This was accomplished by assuming that the radiated UV-LED intensity at the projected area is a constant value at any distance from the center of the lens. This assumption led projector lens was justified because the geometric sensitivity of the LED and the lens is defined by the angular distribution of the projection intensity on the detector plane (see Figure 5).
The aforementioned results were used to determine the values of the design parameters, g and thB, that govern the shape of the lens profile and the overall energy efficiency of the collimated LED beam. It was shown that the double freeform lens can achieve an excellent level of collimation of the emitted UV-LED radiation for a variety of values of these two design parameters.
Single Lens Collimator
The single-lens projector lens is the one most commonly used in LED headlight retrofits because it doesn’t require a separate bulb, ballast or relay harness to work. It simply needs to be connected to an appropriate LED chip set and a standard halogen, bi-xenon or CREE XHP35 LED projector to produce bright, well-controlled lighting on the road.
The most important thing that a great projector can do is to produce enough light to conform with road safety standards and allow the driver to drive comfortably at night. That means a clear, wide, well-controlled lighting pattern that does not blind oncoming drivers. It must also be able to do this without producing excessive amounts of light or a glaring beam pattern that is illegal and dangerous for other road users.
The optical characteristics of a lens can be enhanced using different coatings or materials. In particular, a lens that is coated with an antireflective material or has a high refractive index can be more effective at focusing the Gaussian optical beam into a diffraction limited spot than a flat, smooth polished surface. However, these techniques can add to the overall cost of a projector. As a compromise, many manufacturers use spherical lenses with a slight modification of the surface contour to reduce spherical aberration and increase coupling efficiency.
Red LED Collimator
LEDs offer a number of advantages over conventional mercury arc lamps for inverted microscopy including lower energy consumption, more efficient power-conversion, higher photon density and wider color expression. However, these benefits require the use of a more powerful strobe flash to avoid overheating the LED junctions and reduce camera sensor exposure time to prevent motion blurring in images. This in turn increases the illuminator current demand and limits the maximum duty cycle (DC) so the LED junctions can dissipate heat effectively.
This new collimator solves these issues led projector lens by combining two separate LED emitters into a single high-brightness beam for increased illumination intensity and improved center-spot resolution. It also eliminates the need for iris diaphragms and additional elements to generate conjugate planes allowing a simpler, smaller illuminator to be built with reduced cost and space.
A focusing module is available to direct the light from the collimator into a tight spot which is an image of the LED emitter. This is useful in applications which require very high optical density such as fluorescence spectroscopy. This collimator can also be used to focus light into a fiber or liquid light guide adapter.
To demonstrate the performance of this new product, an Oslon SSL 80 470 nm blue LED and a Lumileds Luxeon Rebel PC amber 595 nm LED were used with a Nikon Ti inverted microscope equipped with a Plan Apo VC 100x/1.40 oil DIC N2 objective. Images were acquired either under critical illumination with the LEDs directly emitted and focused to infinity using the microscope objective lens as the condenser or under Koehler illumination with the LED illuminator housed behind the microscope objective and focused to infinity using a 150 mm achromatic lens. The results show that the illumination was substantially more uniform under Koehler than critical illumination.