Honeywell micro IRU in the Ejets have align in motion capability. GPS required and takes between 15 and 30 minutes. On ground stationary align like most is between 6 and 17 minutes depending on Latitude.
L@ser gyros drift just as spinning gyros did. In the case of the old spinning gyros the major source of drift was the bearings. With l@sers its the imperfections in the mirrors that causes noise.
A strap-down system has to compensate for gravity, earth rotation and the earths spherical shape to work effectively.
Vertical velocity and altitude are calculated using the acceleration that is measured perpendicular to the earths surface. However, an inertial accelerometer cannot distinguish between gravitational force and actual aircraft acceleration. So any accelerometer that isn't perfectly parallel to the earth's surface will measure a component of gravity in addition the the aircrafts true acceleration so the irs has to subtract local gravity from the measured vertical acceleration.
As the gyros measure accelerations in inertial space we need to correct for the earths rotation in inertial space too. Thats once per 24hrs and once per year (people forget about that one) that works out at 15.04 degrees per hour. This correction is subtracted from the measured eastward acceleration. This is known as earth rate compensation. Without it for example, if you were on the equator and flew for 12 hours the gyro would think it was upside down.
Transport rate is the correction for navigating in curved paths over the earths surface as remember the gyros work in inertial space and so the accelerations need correcting or again the gyros would think we were upside down if we flew half way around the earth's sphere.
Now for the trivia:
It takes 3000 volts across the anodes to the cathode to start the lasing action and Honeywell ring laser gyros are triangular. The glass is made from Cervit due to its stability over wide temperature ranges.
The laser does a nice quantum trick of changing frequency to exactly match the path length as the gyro is rotated and its the change in frequency that is used to calculate the rotation rate.