Innovative Freeform Optical Design Improves ICP-OES Speed and Analytical Performance

Significance of the topic

ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) is a cornerstone analytical technique for rapid, multi‐element quantification in environmental, industrial, and research laboratories. Improving optical design directly enhances detection limits, resolution, and analysis speed, enabling more efficient workflows and higher sample throughput.

Objectives and overview of the study

This technical review examines the innovative freeform optical design implemented in the Agilent 5800 and 5900 ICP‐OES instruments. Key goals include reducing instrument footprint, shortening warm‐up and purge times, and enhancing analytical performance through a novel polychromator layout and advanced detector technology.

Methodology and instrumentation

Instruments:

• Agilent 5800 ICP‐OES
• Agilent 5900 ICP‐OES with synchronous dual view pre‐optics
• Freeform collimating mirror integrated into a compact echelle polychromator
• Vista Chip III CCD detector featuring 70 diagonal linear arrays and antiblooming protection

Optical design:

• Customized asymmetric and aspheric freeform mirror corrects spherical aberration, coma, and astigmatism simultaneously across 167–785 nm
• Single‐detector layout eliminates multiple slits or detectors, enabling fully simultaneous wavelength coverage
• Reduced focal length from ~400 mm to 253 mm through optimized mirror surface profile

Detector features:

• High‐speed pixel readout (1 MHz) with duplex circuitry for entire spectrum acquisition in under 0.5 s
• Adaptive Integration Technology adjusts integration times per emission to prevent signal saturation
• Peltier cooling to –40 °C minimizes dark current and readout noise

Main results and discussion

The freeform optic design yields a 50% reduction in polychromator volume, cutting purge and warm‐up durations. Detection limits improve by an average of 40%, and optical resolution reaches under 6.5 pm FWHM for key lines (e.g., As at 188.98 nm). High‐intensity lines produce minimal blooming thanks to pixel‐level antiblooming, while the compact layout maintains stable performance with high‐purity bottled argon.

Benefits and practical applications

• Rapid multi‐element screening and quantitative analysis with full spectrum acquisition in under 0.5 s
• Smaller bench footprint and lower gas consumption streamline laboratory operations
• Enhanced signal‐to‐noise ratios support trace‐level quantification in complex matrices
• Simultaneous measurement of all wavelengths reduces analysis time and increases sample throughput

Future trends and possibilities

Future development may focus on further miniaturization of optical assemblies, integration of machine‐learning algorithms for spectral interpretation, and expansion of freeform optics to other spectroscopic platforms. Enhanced detector materials and cooling strategies could push detection limits even lower, while software advances will improve automation and data analytics.

Conclusion

The Agilent 5800 and 5900 ICP‐OES instruments demonstrate how freeform optical design and advanced CCD technology can transform spectroscopic performance. By combining a compact echelle polychromator, customized mirror surfaces, and a high‐speed, antiblooming detector, these systems offer superior resolution, sensitivity, and throughput, meeting the demands of modern analytical laboratories.

References

1. Agilent Technologies. ICP Expert Software: Powerful software with smart tools for ICP‐OES; publication 5994-1517EN.
2. Agilent Technologies. IntelliQuant Software: For greater sample insight and simplified method development; publication 5994-1516EN.
3. Agilent Technologies. IntelliQuant Screening: Smarter and quicker semiquantitative ICP-OES analysis; publication 5994-1518EN.