OPT3004: Sensor Window/Use of Light pipe

Kishor T

Part Number: OPT3004

Tool/software:

Need clarification on Window calculation for the sensor. Our Sensor is sitting at 10mm from the product casing and for FOV of 45 degree we are getting a window width of 36mm per calculation which we cannot do it in current product.

Can you please suggest on below

1. Can we use a light pipe from the product casing close to the OPT sensor

2. Can you please verify/share the window width needed for 45C FOV and height of 10mm to the casing.

Thanks.

2 months ago

0 Joseph Scherphorn 2 months ago

TI__Expert 4230 points

Hello Kishor,

1) Yes light pipe can be used

2) My simulations showed you will need 22mm diameter hole to achieve 45 deg FOV if sensor is 10mm from surface

Thank you,

Joseph Scherphorn

0 Kishor T 2 months ago in reply to Joseph Scherphorn

Prodigy 20 points

Thanks. If I keep the light pipe close to the ALS sensor, Can I avoid the window? Do you have a recommended light pipe size that can be used in this case?

0 Joseph Scherphorn 2 months ago in reply to Kishor T

TI__Expert 4230 points

Hey Kishor,

Yes if light pipe is utilized hole only needs to be same diameter as lightpipe. lightpipe should be as short as possible span distance needed and should be of diameter large enough to cover entire sensor area on device. You have not specified the package used but pg. 37-38 of data sheet show dimensions for sensor area for the different OPT3004 packages. Use this info to select light pipe diameter

OPT3004 Ambient Light Sensor (ALS) With Excellent Angular IR Rejection datasheet (Rev. A)

Thank you ,

Joseph Scherphorn

0 Kartik Vashisht 2 months ago in reply to Joseph Scherphorn

TI__Intellectual 1585 points

Hi Joseph,
Below is Wipro's team implementation. Can you please check and let us know whether this is fine.

0 Joseph Scherphorn 2 months ago in reply to Kartik Vashisht

TI__Expert 4230 points

Hello Kartik,

I don't see anything wrong but I have handed this off to my associate who has more experience with light pipe design, they will simulate this design and I will reply with results tomorrow

0 Joseph Scherphorn 2 months ago in reply to Kartik Vashisht

TI__Expert 4230 points

Hello Kartik,

What is refractive index of lightpipe?

Thanks.

0 Kishor T 2 months ago in reply to Joseph Scherphorn

Prodigy 20 points

Hello Joseph,

Refractive index of light pipe planned is 1.59.

Thanks,

Kishor

0 Joseph Scherphorn 2 months ago in reply to Kishor T

TI__Expert 4230 points

Hello Kishor,

Sound like you've chosen the Polycarbonate. I don't see any issues with your design, bringing the light pipe closer to the sensor will cause less light leak (if this is concern) as well as delivering a greater portion of the light to the sensor.

Thank you,

Joseph Scherphorn

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OPT3004: Sensor Window/Use of Light pipe