Using irrational linear slopes to increase the precision of spatial light modulators for attosecond metrology

We present a method to increase the effective phase bit-depth of Spatial Light Modulators (SLMs) which utilizes an irrational linear slope as is commonly used to deal with the zeroth order effect. The effectiveness of this technique was demonstrated using precise interferometric transient absorption spectroscopy setups. These setups use high harmonic generation in both solids and gases to generate two ultraviolet pulses that interfere in a spectrometer, providing a measurement of the optical phase. An increase in phase control beyond what the SLM's digital processors would dictate was observed.