The knowledge of LED optical design

Abstract: What is the primary optical design and secondary optical design of LED? Do all LEDs include primary optical design and secondary optical design? Today we will briefly learn the basic knowledge of LED optical design and the field of LED.

Primary optics

When packaging LED chips into LED optoelectronic components, an optical design must be carried out first to solve the range and distribution of LED light angle, light intensity, luminous flux, light intensity distribution, and color temperature. This is an optical design.

Therefore, the primary optical design is mainly the design of the three elements of chip, support and die.

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Main light intensity distribution form of LED light source

The secondary optical

The secondary optical design is for high-power LED lighting: generally high-power LEDs have a primary lens, and the light-emitting angle is about 120 degrees. Secondary optics is to change the optical performance of the light after passing the primary lens through an optical lens. Before high-power LED lighting components become lighting products, optical design is generally carried out twice.

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Therefore, the secondary optical design is mainly to optimize the design of LED lighting appliances. The secondary optical light distribution design of the LED light source is particularly urgent for large-area projection and flood lighting. Through the secondary optical design technology, the design of additional reflecting cups, multiple optical lenses and aspheric light-emitting surface can improve the light extraction efficiency of the device.

The role of secondary optics

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Spread light to a wider range and change its light intensity distribution23718ebd090832ffa01170ec09f5663

The beam is concentrated into a narrower beam

Design principles of secondary optics

The illuminance at any point in the illumination area is formed by the light energy emitted by many points of the light source, which is redistributed by the optical illumination system and superimposed. Optical illumination optical system generally includes: LED light source + optical system + illumination plane

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LED optical lighting design system method

According to the use requirements, the optical system design requirements are put forward to collect the necessary parameter conditions of the optical system, and the “impossible” and “irrational” requirements in optics are eliminated. The overall design and layout of the optical system. The design of the optical part optimizes the optical effect according to the design requirements. Generally, computer software is used to assist in drawing product drawings, considering product processing and shaping, and outputting drawings.

Lamp usage scenarios and test simulation

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LED optical system classification

1. Reflector cup/2. Lens/3. Combination of reflector cup and lens

Generally speaking, lenses can change the light shape more effectively than mirrors.

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LED optical lens material classification

1. Silicone lens:

a. Silicone has high temperature resistance (reflow soldering is also possible), so it is often directly packaged on the LED chip;

b. Generally, the size of the silicone lens is small, and the diameter is generally 5-10MM;

2. PMMA lens

a. Optical grade PMMA (polymethyl lactene with methyl ester, commonly known as: acrylic). This material is relatively brittle after molding and is not suitable for making products with particularly complex shapes;

b. Advantages: high production efficiency (can be completed by injection molding), high light transmittance (the transmittance is about 93% when the thickness is 3mm), disadvantages: temperature resistance 70 degrees, heat distortion temperature 90 degrees;

3.PC lens

a. Optical grade Polycarbonate (PC for short) polycarbonate, which has quite strong toughness and good impact resistance;

b. Advantages: high production efficiency (can be formed by injection molding), high temperature resistance (above 130 degrees); disadvantages: slightly lower light transmittance (88%);

4. Glass lens

It has the characteristics of high light transmittance (97%) and high temperature resistance. Disadvantages: fragile, low production efficiency and high cost.

LED optical lens material classification

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Post time: Sep-18-2020