Abstract: A slit slider assembly for providing a plurality of slits. The slit slider assembly includes: a holder including a first channel and a pair of set screws that each has a ball partially extruding into the first channel; and a slit carrier assembly configured to be slidably disposed in the first channel and carry a slit mask that includes a plurality of slits, the slit carrier assembly including a plurality of dimples for receiving a portion of the ball. When the balls of the pair of set screws engage two dimples of the plurality of the dimples, the holder is configured to pass light through one of the plurality of slits that corresponds to the two dimples.

Abstract: A slit slider assembly for providing a plurality of slits. The slit slider assembly includes: a holder including a first channel and a pair of set screws that each has a ball partially extruding into the first channel; and a slit carrier assembly configured to be slidably disposed in the first channel and carry a slit mask that includes a plurality of slits, the slit carrier assembly including a plurality of dimples for receiving a portion of the ball. When the balls of the pair of set screws engage two dimples of the plurality of the dimples, the holder is configured to pass light through one of the plurality of slits that corresponds to the two dimples.

Abstract: A post holder for holding a post in place. The post holder includes: a casing including a hollow cylinder and a clamping flag defined by a cutout formed in the hollow cylinder; first and second brackets detachably secured to the casing; a cylindrical rod disposed between the first and second brackets and secured to the first and second brackets; and a levered cam disposed between the first and second brackets and having a shape of a comma that includes a tail and a circular disk. The circular disk has a hole that the cylindrical rod passes through, where the hole is offset from a center of the circular disk so that a level of a clamping force that the circular disk applies to the clamping flag changes as the levered cam rotates relative to the casing.