WHAT IT IS
The optical system in ICP-OES captures the light emitted by elements in the plasma and directs it to a detector for measurement. It isolates specific wavelengths of interest, ensuring accurate quantification of the elements in a sample. Optical systems are integral to the instrument's performance, affecting resolution, sensitivity, and dynamic range.
HOW IT WORKS
Light Emission from Plasma – The high-temperature plasma excites atoms and ions in the sample, causing them to emit light at element-specific wavelengths.
Light Collection – The emitted light is collected using lenses or mirrors and directed into the spectrometer for dispersion.
Wavelength Dispersion – A diffraction grating or prism within the spectrometer separates the light into its component wavelengths.
Wavelength Selection – The optical system isolates the desired wavelengths corresponding to the target elements, minimizing interference from overlapping spectral lines.
Detection – The isolated light is measured by a detector, such as a photomultiplier tube (PMT) or charge-coupled device (CCD), which converts the light intensity into an electrical signal for analysis.
TYPES OF OPTICAL SYSTEMS IN ICP-OES
Radial View: Measures light emitted radially from the plasma, offering good matrix tolerance and dynamic range for high-concentration samples.
Axial View: Captures light emitted along the plasma axis, providing higher sensitivity for trace-level analysis by maximizing the optical path length.
Dual-View Systems: Combine radial and axial views, allowing users to switch between modes or simultaneously measure both for optimized performance across diverse applications.
Echelle Spectrometers: Use a combination of echelle gratings and cross-dispersers to achieve high resolution and cover a broad spectral range simultaneously.
ADVANTAGES
High Sensitivity: Advanced optical systems enhance the detection of trace elements by efficiently capturing and isolating emitted light.
Improved Resolution: Precision optics reduce spectral overlap, ensuring accurate analysis of elements with closely spaced wavelengths.
Wide Spectral Range: Echelle spectrometers and other advanced designs provide broad wavelength coverage, enabling simultaneous multi-element analysis.
Versatility: Dual-view systems offer flexibility for analyzing samples with varying concentration ranges and matrix complexities.
Reduced Interference: High-quality optics minimize background noise and spectral interferences, improving data accuracy.
CHALLENGES AND LIMITATIONS
Cost of Advanced Systems: High-resolution spectrometers and dual-view systems increase instrument costs, limiting accessibility for smaller laboratories.
Complex Calibration: Advanced optical systems may require detailed calibration to ensure accurate performance across the spectral range.