Optical indicators of LED lamps and their physical meaning
In this scenario, the brightness of the scene is the part of the light reflected by the yellow arrow and reflected into the human eye.
The indicator of brightness actually contains two meanings in the application of the luminaire. One meaning is the brightness of the luminaire that we talked about earlier. The other meaning is the brightness of the scene being illuminated. It refers to the illumination emitted by the luminaire on the object or the ground. Reflecting some of the light entering the human eye, there is no hard regulation in indoor lighting, but there are clear requirements for outdoor lighting.
The thickness of the phosphor, the width and shape of the boundary phosphor area are all important factors affecting the light distribution design and optical quality.
Light distribution curve:
Describe the absolute or relative illuminating ability of the light source in different directions of the space to reflect the far field intensity distribution information of the light source, corresponding to the light source ies file.
Each ray emitted from the light source, regardless of the optical transformation, the sine of the exit angle is inversely proportional to the exit height, which means that the exit height determines the exit angle.
For the inimum angle of the luminaire, there is a bottom theoretical evaluation caliber
The optical design of the luminaire is a balancing choice under multiple conditions
Under the given constraints (light source, caliber, height, efficiency), try to achieve optical indicators, if not, make a trade-off;
Under the premise of realizing the optical index, transform the structural form of the lens and adjust the balance of the spot distribution;
Under the premise of satisfying the optical index and the spot distribution, the structural form of the lens is changed, and breakthroughs are made in terms of aesthetics and novelty;
The balance between material cost and process cost.
Several typical ways to achieve light control
• There are 3 control degrees of freedom, the incident surface, the refractive index of the material, and the exit surface;
• For the far field is a circular spot, the lens is mostly axisymmetric, and the design is relatively simple;
• For far-field non-circular spots, the corresponding lens is a non-axisymmetric body, especially for some large polarization distributions, the design becomes very complicated;
• High lens efficiency;
• Single lens refractive power is limited;
• There is interface reflection, which is not conducive to glare control.
Reflector + lens
Refractive, total reflection composite light control lens
• The light emitted by the light source is divided into two parts, the small angle part is concentrated by the intermediate convex lens, the large angle part is refracted into the lens body, and then the angle is controlled by the side total reflection, and finally the light exit surface is emitted;
• All the light emitted by the LED light source can be effectively controlled, and the lens efficiency is high;
• Changing the structural form of the lens can change a variety of spot patterns;
• There is an interface that reflects stray light.
Reflective reflection on the inner wall of the structural member
• Light comes from the light reflected from the lens interface, the light that is actively discarded during the design process, and the stray light that overflows the processing assembly error. • This part of the light is usually less energetic and usually appears in the form of background light in the illumination field. However, it is not excluded that the inner wall of the lamp is made of mirrored high-reflection material with a specific structure to seriously affect the spot quality.
• Solution: The inner wall is blackened, the inner wall is treated as a diffuse reflection surface, and a precise optical evaluation is performed.
Reflective of the anti-glare hood at the front of the lamp
• Light may originate from normal outgoing light, or it may originate from the interface reflecting light. It is characterized by the presence of a stray light ring when the light is being illuminated, and the edge layering when the lamp is rubbed against the wall, which seriously affects the lighting effect.
• Use a black mask to absorb.
• Use a diffuse reflector to weaken.
• At the beginning of the lighting plan, the overall optical evaluation of the hood is optimized to minimize the projection of light onto the reflector, allowing the reflected light to be controlled, allowing it to blend well into the main spot.
Thoughts on the application of lighting and the development of lamps
Purpose of lighting
The human eye is equivalent to a camera that can automatically adjust the focus and auto-focus circle.
• Color characterization is the amount of wavelength combination and relative intensity of the object’s light.
• Contrast characterizes the relative difference in brightness of different observed objects.
• Unreasonable distribution, within the main perspective of the human eye.
• The contrast is too large and the contrast is too strong.
• Increase the effective light output and allocate energy and space reasonably.
Indirect lighting anti-glare
Disadvantages: The material characteristics of the reflective area are usually Lambertian diffuse reflection, which produces a large amount of large-angle glare.
Solution: The reflective area of the optical device as a design basis, resorted to the light intensity, angle-controlled.
People-oriented lighting design is long
• The concept of luminaire design changes (the combination of optics and structure, the luminaire should be as small as possible).
• The comprehensiveness of the optical output optical file information (wavelength information, illuminating surface brightness information).
• Optical characteristics of the object to be illuminated (reverse transmittance, inverse transmission ray angle distribution characteristics, selection characteristics for wavelength).