Table 3.
Optical characteristics of the spectrometers and their detectors
| Ultraviolet (UV) | Violet (VIO) | Transmission | |
|---|---|---|---|
| Techniques | LIBS | LIBS, VIS | LIBS, Raman, TRL, VIS |
| Spectrometer type | - - - Crossed Czerny-Turner - - - | Transmission | |
| Spectral range | 243.5–341.7 nm | 382.1–467.5 nm | 535–620 nm, green |
| 620–712 nm, orange | |||
| 712–853 nm, red | |||
| Pixel resolution | 0.0478 nm/pixel | 0.0417 nm/pixel | 0.064–0.090 nm/pixel |
| Channels | 2048 | 2048 | 2048 × 3 |
| Vertical integration rows | 200: 151–351 | 200: 151–351 | Red: 91–161; 21–221a |
| 40: 232–272 | 40: 236–276 | Green: 236–356 | |
| 16: 252–268 | 16: 248–264 | Orange: 378–506 | |
| CCD coating | Enhanced UV | Enhanced Broadband | Enhanced Midband |
| CCD QEb | 77.2% @ 250 nm | 81.3% @ 345 nm | 92.8% @ 635 nm |
| 64.9% @ 300 nm | |||
| 55.4% @ 345 nm | |||
| CCD dark current (e-/pix/sec @ 300 K) | 269 | 202 | 224 |
| Photon response non-uniformity (PRNU) | 4.5% @ 350 nm | 0.7% @ 400 nm | 0.7% @ 650 nm |
| Full well, single pixel | 123k e− | 128k e− | 128k e− |
| Full well serial reg. | 190k e− | 192k e− | 192k e− |
| Conversion gain (e-/DNc) | 3.14 ± 0.06 | 3.16 ± 0.05 | 3.15 ± 0.06 |
aQE, dark currents, and PRNU were measured by the CCD manufacturer
bRed region has options of 70 or 200 row integrations
cDigital numbers, also known as analog-to-digital units (ADU), or counts