Diode-pumped injection seeding lasers produced by Lightwave Electronics Corporation in 1987 and early 1988 have frequency drift of up to 50 MHz per hour, due to temperature drift. Thus they are not useful as wavelength standards for spectroscopy. Units with better long term stability will be introduced in 1988.
Thomas J Kane, Thomas J Kane,
"Frequency Stability Of Diode-Pumped Single-Mode Oscillators", Proc. SPIE 0912, Pulse Single-Frequency Lasers: Technology and Applications, (22 June 1988); doi: 10.1117/12.945499; https://doi.org/10.1117/12.945499