Abstract: A system for unloading inventory items includes an inventory holder, an unloading station, and a mobile drive unit. The inventory holder stores inventory items. The unloading station includes a barrier that is operable to prevent inventory items from moving past the barrier as the inventory holder moves past the barrier. The mobile drive unit is operable to move the inventory holder toward the unloading station and to move the inventory holder past the barrier.

Abstract: A system for unloading inventory items includes an inventory holder, an unloading station, and a mobile drive unit. The inventory holder stores inventory items. The unloading station includes a barrier that is operable to prevent inventory items from moving past the barrier as the inventory holder moves past the barrier. The mobile drive unit is operable to move the inventory holder toward the unloading station and to move the inventory holder past the barrier.

Abstract: A method for unloading inventory items includes storing an inventory item on an inventory holder and moving the inventory holder toward an unloading station with a mobile drive unit. Additionally, the method includes moving the inventory holder past a barrier of the unloading station. The method further includes preventing the inventory item from moving past the barrier as the mobile drive unit moves the inventory holder past the barrier.

Abstract: A method for unloading inventory items includes storing an inventory item on an inventory holder and moving the inventory holder toward an unloading station with a mobile drive unit. Additionally, the method includes moving the inventory holder past a barrier of the unloading station. The method further includes preventing the inventory item from moving past the barrier as the mobile drive unit moves the inventory holder past the barrier.

Abstract: An assembly for use in a laser instrument which produces a plane of laser light by reflection from a cone. The assembly includes a weak focusing lens which improves the control over the planarity of the plane of light produced. Because it is weak, the weak focusing lens can be positioned over a relatively large distance to produce slight changes in the focus of the beam which is reflected to produce the plane of light. Critical, time consuming, and expensive manufacturing requirements can be relaxed, while improved performance results in superior laser instruments.

Abstract: An assembly for use in a laser instrument which produces a plane of laser light by reflection from a cone. The assembly includes a weak focusing lens which improves the control over the planarity of the plane of light produced. Because it is weak, the weak focusing lens can be positioned over a relatively large distance to produce slight changes in the focus of the beam which is reflected to produce the plane of light. Critical, time consuming, and expensive manufacturing requirements can be relaxed, while improved performance results in superior laser instruments.

Abstract: A focus compensating lens structure wherein a lens means for collimating laser light produced by a source has an index of refraction which varies with temperature and wavelength to compensate for temperature effects on the wavelength of light produced by the laser source and the length of the mounting on which the source and lens are disposed.

Abstract: An orthogonal light plane generator is associated with a primary light plane generator to convert a portion of a first light plane projected by the primary light plane generator into a second light plane substantially orthogonal to the first light plane. The orthogonal light plane generator comprises a diverter which defines three or more reflecting surfaces for receiving a portion of the first light plane and redirecting that portion as the second light plane. The three or more reflective surfaces are oriented relative to one another such that tilting of the orthogonal light plane generator is compensated to maintain the orthogonality between the two light planes. Tilting about one axis results in offset of the second light plane and tilting about a second axis orthogonal to the first results in a shifting of the sector within which the second light plane is projected, but tilting about either axis does not affect the orthogonality between the planes.