Page 182 - Tunable Lasers Handbook

160 Charles Freed

TABLE 19 An Example of IR Synthesis at 16 pm with Regular Band
CO, - Transitions. Wave Number = (2 x Transition 1) - (Transition 2)"

W7ave number (cm-1) Transition 1 Transition 2
614.906042 W602 I-P(40) 13C'602 11-R(30)
674.915792 14C160, I-P(28) 12C160180 11-P(16)
621.9 17820 14C1607 I-P(48) IT160180 11-P(56)
624.937049 ll-C1602 I-P(56) 13C1802 11-P(26)
621.945145 14C16O9 I-P(1-l) W160180 11-R(16)
624.954490 1W607 I-P(4) IVSO, 11-R(26)
623.978786 14C1602 I-P(48) 'T'607 11-R(6)
624.988389 14~160~ 1-~(20) 1x160'80 II-R(l)
625.00785 1 14C1602 I-P(16) W80, II-P(4)
625.0 1374 1 IJC16O2 I-P(6) 12C16O,II-R(56)
625.044477 14c1602 I-P(2) 12C160180 II-R(52)
625.046863 W1607 I?(%) lW802 II-R(52)
625.09 1263 I'CI6O7 I-P(4) 12C160180 II-R(45)

OReprinted with permission from Freed [75]. 01982 IEEE.

in Fig. 18. For instance, heterodyne comparisons with the second harmonics of
appropriately selected CO, laser transitions have achieved the first accurate
determination of several CO-isotope laser lines in the 5- to 6-ym range. This
work was carried out by Eng et al. at MIT Lincoln Laboratory in 1974 [17]
with the use of (third-generation) ultrastable CO, and CO lasers [148,149] and
high-quality crystals of the calcopyrites CdGdH, &d HgGaSe.
Yet another example of ultraprecise IR synthesis at 16 ym (625 cm-1) is
illustrated in Table 19 [ 161. To generate Table 19 we gave a computer the task of
finding the C0,-isotope laser transitions for which the difference frequency
between a frequency-doubled 14C1607 laser transition and any other C0,-isotope
laser transition fell within the 625.0f 0.1 cm-1 frequency range. Synthesized
frequency tables very similar to Table 19 have been used for the accurate
determination of absorption lines in isotopes of uranium hexafluoride (UF,) near
16 pm.

ACKNOWLEDGMENTS

In compiling this chapter I most often used results and examples of research
at MIT Lincoln Laboratory because this was the work with which I was most
familiar. However, my own contributions to the results are due to the active
encouragement and cumulative efforts of many individuals in the MIT/Lincoln