638 nm laser is not like the traditional 660nm or 650nm red laser.
You can purchase all kinds of 638 nm laser diodes at BeamQ .
Other 638nm Laser :
Here is HÜBNER Photonics selection of solid state 638 nm lasers. Choose between diode lasers with powers up to 180 mW and tunable lasers. The diode lasers by Cobolt are sold seperately or can be combined with other wavelengths into a multi-line laser or laser combiner. Perfect for interferometry, microscopy, Raman spectroscopy and holography.