Design And Construction
The first step is to choose the type of light source, in order to avoid tedious and error prone alignment work and budget overruns, we have abandoned low-power lasers and instead opted for LED light source, which is more economical and whose brightness are thousands of times of that of lasers.
The detection wavelength has exceeded the response wavelength of ordinary silicon photodetectors. We decided to use indium gallium arsenic photodiodes as our light intensity detectors, which have a fast response in the wavelength range of 800-1700nm and can quickly convert the measured light intensity into current output.
Because photodiodes can only generate weak photocurrent and are not suitable for measurement, we have adopted maximum energy A current voltage conversion amplification circuit with a magnification of 200000. Finally, we measured the output voltage of the module. We used a data acquisition card on the instrument and obtained the voltage results on the computer, which also facilitates the subsequent fitting of a large amount of data obtained.
The reason for using multi-channel is that we not only need to measure real-time photovoltage, but also the corresponding LED supply electrical voltage to minimize the impact of voltage instability. In terms of power supply, due to the different voltages required for each part of the circuit, we have chosen a linear DC power supply with multiple gears to meet all voltage requirements at once. In terms of heat dissipation, due to the high power of LED light sources, we have purchased a phone heat dissipation back clip to cool it down, which minimized the impact of high temperature on bulb power as much as possible.
In terms of fixing the device, we first used 3D printing, and then fixed the optical path and circuit together through drilling, ensuring both aesthetics and consistency in multiple experiments.
The final experimental setup is shown in the following figure:
