  We report on efforts to improve the speed of low-G far-infrared
transition-edged-sensed bolometers. We use a fabrication process that does not
require any dry etch steps to reduce heat capacity on the suspended device and
measure a reduction in the detector time constant. However, we also measure an
increase in the temperature-normalized thermal conductance (G), and a
corresponding increase in the noise-equivalent power (NEP). We employ a new
near-IR photon-noise technique using a near-IR laser to calibrate the
frequency-domain multiplexed AC system and compare the results to a
well-understood DC circuit. We measure an NEP white noise level of 0.8 aW/rtHz
with a 1/f knee below 0.1 Hz and a time constant of 3.2 ms.
