Spectrophotometric system employing 110m and 30m long multipass cells
The spectrophotometric system is intended for:
- absolute measurements of absorption coefficients of the atmosphere and its gaseous constituents separately with the sensitivity up to 10-8cm-1;
- investigation of continuum absorption at long paths imitating real atmospheric paths at pressure, temperature, and humidity variations;
- investigation of the dynamics of the radiation from any cw or pulsed lasers operating in the IR, visible, and UV regions at long paths in air and molecular gases;
- calibration of laser spectrometers of other types and local and remote gas analyzers.
This system can be used for solution of principal problems on atmospheric spectroscopy and propagation of laser radiation through the atmosphere.
Additional information is available on request: yupon@iao.ru.
Specifications of the system
Parameters of multipass gas cells
.
| Spectroscopic cell |
|
| length, m |
30 |
| diameter, m |
1.1 |
| pressure, mmHg |
5 10-5 - 103 |
| temperature, K |
288 - 350 |
| Atmospheric cell |
|
| length, m |
110 |
| diameter, m |
0.7 |
| pressure, mmHg |
5 10-4 - 103 |
| temperature, K |
288 - 330 |
Parameters of lasers
| Alexandrite laser |
|
| tuning range, nm |
720 - 780 |
| band width, cm-1 |
5 10-3 |
| pulse repetition frequency, Hz |
< 10 |
| pulse duration, ns |
180 |
| pulse energy, J |
> 10-3 |
| YAG:Nd laser |
|
| wavelength, nm |
1064 |
| band width, cm-1 |
< 0.05 |
| pulse repetition frequency, Hz |
< 50 |
| pulse duration, ns |
2 - 2.5 |
| divergence |
diffraction-limited |
| pulse energy, J |
> 1 |
| Nd-glass laser |
|
| tuning range, μm |
1.045 - 1.065 |
| band width, cm-1 |
5 10-3 |
| pulse duration, s |
6 10-8 |
| pulse energy, J |
0.2 |
| YAG:ТmСrНо laser |
|
| wavelength, nm |
2080 |
| band width, cm-1 |
< 0.01 |
| pulse repetition frequency, Hz |
< 10 |
| pulse duration in free lasing mode, s |
< 4 10-4 |
| pulse duration in the Q-switching mode, s |
5 10-8 |
| energy, J |
0.3 |
| YAG:Er laser3Y3Al5O12 |
|
| wavelength, nm |
3000 |
| band width (averaged), cm-1 |
< 8 |
| pulse repetition frequency, Hz |
< 50 |
| pulse energy, J |
< 1 |
| tuning range, nm |
10 |
Parameters of the recording system
| Parameter |
Valie |
| error in determination of line positions, cm-1 |
< 5 10-3 |
| error in measurement of gas transmittance |
0.1 - 1 |
| error in pressure, mmHg |
< 0.1 |
| threshold sensitivity, cm-1 |
10-8 |
