Reply to post: Re: Too good to true?

Hear us out: Smartphone lidar can test blood, milk

Jaybus

Re: Too good to true?

My experience is with using LIDAR with modulated visible range lasers to evaluate heat damage in composite materials used in aircraft. I'm an engineer and worded on the data acquisition and coding, not one of the scientists, but I can tell you that special sensors, either PMTs or "silicon PMTs", which are arrays of avalanche photodiodes, were needed to measure the tiny signal gathered from the back-scattered light. These have a gain of between 10^6 - 10^8, whereas the gain on the photodiodes used in a phone's CMOS sensor(s) have a gain of between 10*2 and 10^3. The analytical chemist said that the SNR would be far too small if photodiodes were used. Just saying.

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