Progress towards a ``blue'' potassium MOT

One difficulty when preparing quantum degenerate gases of potassium 40 is the low efficiency of sub-Doppler cooling. In this talk, we discuss how we are attempting to circumvent this problem by implementing a ``blue'' MOT for $^{40}$K on the non-cycling 4S$_{1/2}\rightarrow$5P$_{3/2}$ transition, which has a wavelength of 404.53nm and a decay rate of 1.17MHz. The Doppler temperature should be 27$\mu$K, which is a factor of five improvement over the D2 transition at 767nm. This lower temperature would also facilitate in-situ imaging of atoms in optical lattices. The laser setup consists of a cooled diode injection locked to an external cavity diode laser. The master laser is in turn locked to $^{39}$K saturation spectroscopy in a heated vapor cell. The proximity of this 4S-5P transition to the wavelength used in ``Blu-ray'' technology provides a relatively inexpensive source of laser diodes with powers up to 150mW. A dual MOT will be implemented using dichroic mirrors and waveplates for loading and capture with 767nm, followed by a switch to a ``blue'' MOT for late-stage cooling before loading into a magnetic trap. We will also present results on the spectroscopy of the $^{40}$K 5P$_{3/2}$ hyperfine levels using our setup.