Cleared Tissue LightSheet (CTLS) is a large field light-sheet microscope designed to image whole organs at high speed. CTLS creates a focused sheet with a narrow waist for better optical sectioning, then uses a spatial light modulator (SLM) to rapidly shift the waist of the sheet along the axis of propagation. A dual excitation setup allows imaging from the right and left sides of the specimen for optimal light-sheet projection throughout. Piezoelectric stages move the specimen in x, y, and z with sub-micron resolution. The result is clear: a 1 cm3 volume can be imaged at up to 1µm x 1µm x 3µm (XYZ) resolution. A cleared mouse brain can be imaged in as little as 1.5 hours at 25µm x 25µm x 25µm (XYZ).