Photodetector Puns

Hi everyone, just playing around with some photodetector designs for my photo spectrometer. I have never played with photodiodes before, and I won't be able to get any in time for when I am supposed to be finishing this project to experiment. Mode of operation aside, will my idea (shown) hold up? I need a strictly linear relationship between incident light intensity (strictly W/m2) and ADC voltage.

For the transimpedance amplifier circuit, I can only find performance graphs of "voltage vs light", without specifying which optical quantity they are talking about, which is pretty frustrating.

I've included my rationale and thinking in the image, any input would be hugely helpful thank you!!

https://preview.redd.it/g0ck98y0e4g71.png?width=1102&format=png&auto=webp&s=34d0fa85450c8b72a4ce30db3b9df7d2e3a38e8c

Hi all, I'm new to this group and new to optics as a whole! My honours year project concerns the prototyping of a high precision, spinning-grate photo spectormeter. Long story short, I need to analyse the intensities of wavelengths across the visible light spectrum. However, I am aware that my detector does not have a flat spectral response to incident light.

Are there any good methods of implementing say a white light source with an entirely known and QUANTIFIED spectrum (from what I have seen, datasheet graphs are low precision) to generate a look up table for calculating the true incident intensity at each wavelength of visible light?

TLDR: where to find a white light source with flat or heavily detailed and quantified spectral output.

Thanks for having me and I'd love to answer any questions you might have or any clarification required!

I was working to improve a design built around the below RGB unit from knightbrite. I made some headway in the below post, but the RGB unit has a common cathode, so it can't be used in the way proposed.

So, I'll need to use individual photodiodes for R, G and B. I can apply tinting filters, but I'd prefer diodes engineered for each wavelength as if my existing RGB sensor were broken out into individual diodes.

Any help?

https://www.kingbright.com/attachments/file/psearch/000/00/00/KPS-5130PD7C(Ver.16).pdf

https://www.reddit.com/r/AskElectronics/comments/nyes3r/best_circuit_to_record_the_last_rising_edge/

Hello all,

I have an upcoming project that involves lasers, fiber optics and a small arduino; part of it involves sensing a laser light and turning a pin on / off if there's no light. It needs to be able to respond in 10 milliseconds or less; I don't think a photoresistor is going to be fast and reliable enough for this. Would any of you all have any recommendations on a fast photodetector / photodiode (and part number if you have it!) Do you all think an Arduino nano would be able to handle this speed?

Hi again! I am working on an undergraduate research project, looking at developing a remote sensing device that is able to measure both radiance and irradiance. If any of you guys know about spectrometer/telescope/irradiance sensor design I'd love to hear about it!

The main wall I'm hitting is how to use hardware to interpret the incoming radiance at wavelengths across the visible light spectrum, with the highest resolution possible. Do I need to develop a custom circuit, or could this be something I can get away with using a webcam (or, perhaps, an arducam?) to do.

Hi,
I wanted to control two LEDs and IR and RED LED for creating an oximeter. I have only one photodetector so that i need to turn on the red led for a time interval and IR led for another time interval. Both leds should not be turned on at the same time. So that i can take readings of both ir and red led using one photodetector. How to do this?? Please help. I'm using ATMEGA328P, programming in embedded C,using Microchip studio(former atmel studio).

Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c12818

Yongjie Chen, Yingqi Zheng, Yuanyuan Jiang, Haijun Fan, and Xiaozhang Zhu

https://ift.tt/38929mS

Hi everyone,

I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs, https://www.thorlabs.com/drawings/275cb418cdc2cf1f-A2E46103-D9C0-3581-4553E3D3CA93AD83/DET01CFC-Manual.pdf) that generates a current. For my experiment, I would like to amplify this signal with an amplifier to subsequently read it out with a digital oscilloscope.

The amplifier that I use is the LNA-1440 (https://rfbayinc.com/products_pdf/product_88.pdf) with an input impedance of 50 Ohm. Since the input impedance of the amplifier matches the source impedance of the photodetector, I connected them directly with an SMA-cable.

The problem that I am facing right now is that the signal gets attenuated for frequencies larger than a few MHz, i.e. it seems as if my circuit acts as a low pass filter. Do you have an idea why this could be the case?

Thank you very much for your advice!

Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c02675

Yingjie Zhao, Yuchen Qiu, Jiangang Feng, Jiahui Zhao, Gaosong Chen, Hanfei Gao, Yuyan Zhao, Lei Jiang, and Yuchen Wu

https://ift.tt/3bybBSK

I have a photodiode and it outputs a current. Now the voltage is measured over the load resistance.

What is the load if I use a 50 Ohm cable and 50 Ohm termination on my oszi? My guess would be 100 Ohm since they are in series. Does it work this way?

Are there some books which are good to learn stuff like that?

• Kwon, Hyeokjin, et al. "Laser-Induced Digital Oxidation for Copper-Based Flexible Photodetectors." Applied Surface Science (2020): 148333.
• Publisher link: https://www.sciencedirect.com/science/article/abs/pii/S0169433220330907
• DOI: 10.1016/j.apsusc.2020.148333

<3 you knowledge-sharing heroes :) This was just published a few days ago, which is why I suspect it's not available in the usual places.

Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c08189

In-Hyeok Park, Ki Chang Kwon, Ziyu Zhu, Xiao Wu, Runlai Li, Qing-Hua Xu, and Kian Ping Loh

https://ift.tt/374njTp

Data is gathered from a metal 3d printing system. Any thoughts on what could be causing this distortion. My initial guess would be this is due to the f-theta lens.

https://preview.redd.it/m54z6r5e8hh41.png?width=596&format=png&auto=webp&s=2b260d7dc686bcc5ebb7815f8f7867f4b391f014

Hi everyone,

I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs, https://www.thorlabs.com/drawings/275cb418cdc2cf1f-A2E46103-D9C0-3581-4553E3D3CA93AD83/DET01CFC-Manual.pdf) that generates a current. For my experiment, I would like to amplify this signal with an amplifier. The amplifier that I can use is the LNA-1440 (https://rfbayinc.com/products_pdf/product_88.pdf) with an input impedance of 50 Ohm.

The signal from the photodiode spans a frequency-bandwidth from around DC to 100 MHz. What kind of circuit would you use to amplify the signal from the photodetector with the amplifier? For example, would it work to connect the photodetector directly to the amplifier since they seem to have a matching impedance, or do I need something in between (e.g. a resistor in parallel)?

Thank you very much for your help :)