Apparatus (4) for converting an optical theodolite (2) into a laser theodolite, which apparatus comprises a laser diode adapter (6) for connection to the optical theodolite in place of an eyepiece of a telescope (8) of the optical theodolite, and driver means (10) for the laser diode adapter (6); the laser diode adapter (6) comprising a housing (12), a laser diode (14); a holographic image reshaping lens (51), and a focusing lens (52) in the housing (12), and an externally threaded male portion (16) for screwing into the telescope (8) in place of the eyepiece; and the driver means (10) having securing means (18) for securing the driver means (10) to the optical theodolite (2) remote from the laser diode adapter (6).

The present invention provides apparatus and a method for projecting an indication of alignment. The invention features forming a first output beam, and a second output beam that is substantially perpendicular to the first output beam. The first output beam indicates level, the second output beam indicates plumb, and the first and second output beams together indicate square. An error indicator indicates an error in the accuracy of the first and second output beams as indicators of level and plumb respectively. The error indicator can be deactivated, such that the first and second output beams together can be used at least to indicate square.

A line generating device may include a housing having a bottom surface, a top surface, a front surface connecting the top and bottom surfaces, a rear surface connecting the top and bottom surfaces, and a side surface connecting the top and bottom surfaces, a support assembly mounted within the housing. In addition, the device may include a light source mounted on the support assembly, and a lens for receiving light and projecting the light in the shape of a fan within a plane. The light plane exits through the front surface. The device is disposable on a reference surface on the bottom, rear and side surfaces.

A tool for use in checking the level or grade of the ground surface in a construction area or site using a daylight visible wavelength semiconductor laser diode module to project a laser beam from the location of interest to a location where the elevation or the amount of cut or fill is known. The tool is a relatively small, hand-held and compact device that utilizes batteries contained within the tool to power the laser diode. The laser diode module fits within a module plug that fits within a module plug compartment in the front of the tool. A front end cap encloses the laser diode module and the module plug in the tool. The laser beam emitted from the tool is in axial alignment with an edge or ridge on outside surface of the tool. A bubble level ensures that the tool is held parallel to the ground during use.

A height indicating instrument useful for preparing flat and level cementitious floors over an uneven sub floor. The instrument includes first and second rod assemblies, the first having a foot engagable with the surface of a sub floor and the second assembly operatively attached to and moveable axially with respect to the first assembly. The second assembly includes a height indicator to indicate the desired underlayment height, and carries a laser beam detector. A laser beam generator generates a horizontal laser beam detectable by the laser beam detector. Vertical movement of the second rod assembly with respect to the first rod assembly to horizontally align the detector with the generator simultaneously moves the height indicator to adjust elevation of the latter with respect to the foot. At a plurality of locations on the uneven sub floor, slurry is poured until the slurry rises into contact with the height indicator at each such location.