Choosing IR Illuminator LED for LIDAR design

[AndrewLoomis]

I'm making a LIDAR time of flight sensor, and recently discovered TI's new chip: OPT3101.
http://www.ti.com/product/OPT3101/technicaldocuments

This chip isn't even in production yet, but very cool. Pretty much just add your own LED and photodiode, and you're set. The OPT3101 allows you to have 3 independent illuminators that are multiplexed, so I am looking to have 3 separate 20-30 deg FOV LED's to get a range finding FOV of 70-90 deg. The problem is that I have found no resources to calculate max range given the FOV of LED, radiant intensity, and illumination power. I've looked through the datasheet: http://www.ti.com/lit/ds/symlink/opt3101.pdf

and the app note: http://www.ti.com/lit/an/sbau305/sbau305.pdf

without being able to find an equation or estimate for max range. I'm new to optics/time-of-flight so I may be missing something. This is the LED I'm currently looking at using:  https://www.digikey.com/product-detail/en/osram-opto-semiconductors-inc/SFH-4655-Z/475-1260-1-ND/1468205

[_Wim_]

Hi, thanks for pointing us to this interesting new chip.

From glancing through the datasheet, it seems that the calculations you need are explained in detail in 8.2.2.4. First you calculate the noise current with the chosen sample rate, photodiode capacitance and ambient current (see chapter before to calculate ambient current). This noise current defines your maximum range and resolution (at max range this is the minimum current you will still receive from the photo diode).

Below are the formulas to calculate the required optical power from the light source (led or laser). Once this is calculated, you can then calculate the minimum detectable distance below (when the device saturates because of too much light).

[AndrewLoomis]

Thanks for the reply, I ended up figuring it out, and even found an error in the datasheet that I reported to TI . One of the first equations had a misnamed variable that through me off. After I read a lot more into how lidar and time of flight works, the equations made sense. Thanks again for confirming though, I'm excited to start working with this chip!