Fast PCR instrument in-line LED solution

For the irradiation end of the rapid PCR instrument, if a 5/8/10mm diameter in-line LED is used, the optical path is shown in Figure 1 after optimized design. The light emitted by the in-line LED is first collimated by a plano-convex glass lens, and then passed through a tape Filter the light through the filter, and finally condense the light into the fiber through a glass spherical lens. Plano-convex glass lens and filter, glass ball lens fiber pass light, numerical aperture NA = 0.56. Separation between filter and glass ball lens = 3-5mm. The light spot at the end face of the fiber is shown in Figure 2. ZEMAX simulation found that the energy utilization rate of light is about 25.658%, compared with the packaged SMD LED (the energy utilization rate of light is about 85%)

Figure 1 Light path of the irradiation end (using in-line LED)

Figure 2 Spot at the fiber end face

The above simulation is based on the wafer of medium and high power chips. The thickness of the wafer is assumed to be 120 μm, and the six sides of the wafer are illuminated. The wafer is in contact with the bottom of the reflector cup of the bracket.

The driving current of the LED is expected to be turned on to 100mA. If it is greater than 100mA, the light intensity will be high at the moment of lighting. If it is lower than 100mA, the light intensity is not enough to stimulate the fluorescence of low-concentration reagents, which will affect the sensitivity.

In terms of wavelength selection of LED, the following are preferred: 1. Peak wavelength 430nm; 2. Peak wavelength 470nm; 3. Peak wavelength 520nm; 4. Color temperature 4000K full spectrum white light; 5. Peak wavelength 630nm, or color temperature 3000K white light; 6. Peak wavelength 740nm.