I am currently building my own Raman spectrometer and I am in the process of choosing a light source. I am deciding whether I should be using LEDs vs traditional laser modules.
These are my requirements (in order of importance):
- Price - I am interested to keep the cost of my prototype as low as possible because there is a possibility of this turning into actual mass production. (For the sake of comparison, a "good" LED costs in tens while a "good" laser source can easily fetch in thousands).
- Performance - Ideally, the output from light source should be predictable and consistent. I understand that LEDs produces a lot of heat and this can cause the LED to output different wavelengths.
- Energy consumption - I am trying to build a portable unit, so power consumption is a critical aspect of my design.
Traditionally, Raman spectrometers have always employed lasers as their light source. However, I feel this discussion would be helpful to others who are in the same boat as me as there has been significant improvements in LED pricing and performance.
I have also considered using a grating in junction with my LED to focus only a narrow band of light onto my sample but this would result in high energy lost from stray lights.
Note that I am designing this spectrometer to be used exclusively with SERS (Surface enhanced Raman spectroscopy) so my requirements are less stringent as the substrate will greatly enhance the output signal from my sample.
Can someone shed some wisdom on the feasibility of building a low cost light source comprised only of LEDs for my purpose? By the way, I am trying to aim for 785nm.