Optical pumping of helium, using the 23S–23P line at 1.083 μm, can be performed with a tunable neodymium laser [La1−xNdxMgAl11O19 (LNA)]. The LNA crystal, longitudinally excited by an Ar+ gas laser, delivers a usable power of about 300 mW. A 3He cell at 0.3 Torr can thus nuclearly polarized up to 60%. Preliminary results are also obtained with a LNA laser pumped by discharge lamps.
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Daniels et al. (1987) studied this question.