Optical technology puts the "real time" in RT-PCR. As the amplifying enzyme produces duplicate copies, fluorescent molecules are released into the buffer solution. Total fluorescence is measured in real time after each cycle and, for positive samples, increases as the number of amplicons increases. By measuring the intensity buildup during thermal cycling, viruses can be detected and the amount of virus present (viral load) can be estimated.
As the new coronavirus spreads around the world, patients, technicians, and scientists are relying on the latest molecular analytical instruments in the fight against the virus that causes the disease. Optical and photonic technologies embedded in these instruments (e.g., high quantum-efficiency multispectral cameras, visible laser diodes and LEDs, infrared radiothermometer arrays, narrow-band filters, and broadband multispectral spectrometers) play a critical role.