Technology description and performance
Description of miniRaman technology
Optical schema of MiniRaman MRs. See details for MiniRaman MRs patent here:
MiniRaman spectrometer is an advanced miniaturised Raman spectrometer with clear aperture on optical elements of 4 mm. The total dimensions of the miniRaman spectrometer module are 25 x 30 x 105 mm including two lasers, laser beam delivery optics, set of sample probes, Raman beam delivery optics, electronics, battery and housing.
In order to obtain an automatic calibration of the unstabilised laser wavelength drift, Lightnovo implemented a unique (patented) reference channel in our spectrometer. Therefore, the MiniRaman measurements are calibrated after each new spectrum. MiniRaman has an extremely high total Raman signal throughput from sample to detector (~89%).
The device has the following output specification:
- lasers at the wavelength: 660 nm and 785 nm
- laser power can vary between 2-30 mW at 660 nm, 15 to 150 mW at 785 nm
- spectral range 2750-4500 cm-1 at 660 nm, 400-2500 cm-1 at 785 nm
- spectral resolution 10-15 cm-1 (depending on a spectral range)
- wavenumber accuracy ±2.5 cm-1
MiniRaman Product development
One of the key problem during the development of such a small and cheap device was the wavelength and power stability of the lasers. This has been solved with the presence of a piece of polystyrene inside the device as a reference material for calibration. In this way, both lasers measure the Raman spectrum of polystyrene and the Raman spectrum of sample during each acquisition. The spectrum from the sample gets always corrected from the polystyrene spectrum for Raman shift and Raman intensity. This allows for a constant calibration of the device and, therefore, the results are fast (no need for a long calibration) and reliable. This feature makes device an ideal solution for identification and quantitative measurements.
MiniRaman spectrometer has an internal battery (1000mAh) which allows continuous device operation for 2 hours (with turn on lasers). Therefore, miniRaman spectrometer becomes even more handy since it can be used just with one hand without the need of cables for the external battery.
MiniRaman spectrometer can be operated via desktop version of the software and by app for Android. Moreover, device has a software package for identification and quantification of chemicals (correlation with spectral data base, PCA, PLS, NNLS, MCR). Identification includes the possibility to make a Raman spectral database of different materials in order to use miniRaman spectrometer to detect the presence of a compounds in a sample.
MiniRaman MRs performance control
After each production, the device is tested checking wavelength accuracy, Raman shift accuracy, laser power calibration and signal to noise ratio (SNR) obtained on polystyrene sample.