In laser lighting applications, there are two keys to the formation of white light. The first is that the blue light can be converted into a sufficient amount of yellow light through the phosphor crystal material, and the second is that the yellow light is mixed with the remaining blue light to form white light. Due to the directivity of blue light, the light distribution in space is relatively concentrated, it is not easy to mix with the yellow light (distribution as Lambertian light shape) to form white light (Figure 1).
Therefore, in the optical design, the high-directivity, energy-intensive blue light must be diffused through the MEMS mirror and then incident on the fluorescent crystal. In addition, in order to convert enough yellow light, the thickness of the crystal in the blue light incident direction should not be too thin. If the thickness is only 200-300um, most of the blue light will penetrate, and it is not easy to form white light. Whether laser lighting can be popularized depends on the cost of crystal material and the complexity of optical design. Therefore, TAC developed a patented composite fluorescent crystal material according to the needs of the client, which can produce laser lighting through a simple optical system (see Figure 2).