OPT101: OPT101 non-linearity vs irradiance uniformity

Daniele Paesani

Part Number: OPT101

Hello,

the OPT101 datasheet states that "If the light source is focused to a small area of the photodiode, nonlinearity occurs at lower radiant power". Is this due to an intrinsic electric phenomenon or this sentence is explaining that a large area photodiode signal will integrate a non homogenous irradiance all over its surface (with non linear effects)?

Also, will this phenomenon occur both in photoconductive and photovoltaic modes?

Let's assume we are detecting a collimated beam producing a homogenous spot whose size is constant but less than the photodiode area. Why will the OPT response suffer from non linearity with regards to beam intensity in this situation?

Is there a way to approximately quantify the non linearity due to this aspect?

Thanks and best regards,

over 4 years ago

0 Alex Bhandari-Young over 4 years ago

TI__Mastermind 25815 points

Hi Daniele,

Yes, this is saying that the photodiode response is linear if the conditions stated are met. The conditions include full sensor area illumination and photoconductive mode.

Best,

Alex

0 Alex Bhandari-Young over 4 years ago in reply to Alex Bhandari-Young

TI__Mastermind 25815 points

Following up to answer your last two questions, as this is one of our older devices I cannot provide much detail into the device operation past what is stated in the datasheet so cannot give those types of details.

Best,

Alex

0 Daniele Paesani over 4 years ago in reply to Alex Bhandari-Young

Prodigy 60 points

Thank you for your answer.

Just in qualitative and more general terms, do you know what is the technical/physical phenomenon which leads to this non-linear behaviour in the said conditions?

Thanks,

Daniele

0 Alex Bhandari-Young over 4 years ago in reply to Daniele Paesani

TI__Mastermind 25815 points

Hi Daniele,

Since this is an older part I do not have the full design details to pull from in answering you. To give a general answer, I believe it is due to averaging across the sensor area, but cannot give more info than this, unfortunately.

Best,

Alex

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OPT101: OPT101 non-linearity vs irradiance uniformity