  The ability of spatial light modulators (SLMs) to modify the amplitude and
phase of light has proved them invaluable to the optics and photonics
community. In many applications the bit-depth of SLMs is a major limiting
factor dictated by the digital processor. As a result, there is usually a
compromise between refresh speed and bit-depth. Here we present a method to
increase the effective bit-depth of SLMs which utilizes a linear slope as is
commonly applied to deal with the zeroth order effect. This technique was
tested using two interferometric transient absorption spectroscopy setups.
Through the high harmonic generation in gases producing a train of attosecond
pulses and harmonics from solids in the ultraviolet, two pulses are generated
that interfere in the far field providing a measurement of the optical phase.
An increase in the precision far beyond the limit dictated by the digital
processor in the bit-depth was found.
