Measurement range (with receiver)
The longest measurement range provided by a laser level (see “Type”) when using a special receiver with a photocell.
Thanks to its sensitivity, such a receiver is able to respond even to a weak laser beam, the mark from which is no longer visible to the naked eye; At the same time, the area of the photocell is quite large, and special indicators make it possible to determine the exact position of the mark. Among other things, this significantly expands the range of action of the level - the measurement range with a receiver is usually several times greater than without it. On the other hand, such equipment inevitably affects the overall cost of the device; and in some models the receiver
is not included in the package at all; it must be purchased separately. However, the second option also has its advantages: you do not need to immediately pay for an additional accessory, it can be purchased later, when a real need arises, while some models allow you to choose the optimal receiver model from several options at your discretion.
Note that the receiver can be useful not only for increasing range; These points are described in detail in paragraph “Included parts”.
Vertical projections
The number of vertical projections issued by the laser level during operation.
Most modern levels are designed for a strictly defined position when working; accordingly, the
projection is called vertical, carried out from top to bottom relative to the standard position of the device. If there are several such planes, the level can be used for two or even three walls at once — this is useful, for example, for the simultaneous work of several people. At the same time, there are portable devices that can be used in different positions; for them, the main working plane is called vertical, although during operation it can be located both horizontally and at an angle, depending on specific tasks. Also note that the vertical projection can also give a horizontal line — for example, when installing a level on the floor.
Note that the number of projections is calculated not by geometric planes, but by individual laser elements, each of which is responsible for its own “work area”. For example, if the level has two vertical elements located at opposite ends and directed in different directions, they are considered as two projections even if these projections lie in the same plane.
Point projections
The number of individual points projected by the laser tool — rangefinder or level, see "Type" — when working. In the first case, one
point projection is standardly provided — more is simply not required to measure distances. In levels, there can be several points, and some models do not have planar projections at all and work only with points. This format may not be as convenient as displaying lines; at the same time, with the same laser power, dot marks shine brighter and are more visible, especially at long distances. In addition, there are certain types of work for which point projection is considered optimal — for example, laying sewers, determining the locations for two holes in opposite walls, etc.
Nadir
Nadir in this case is called a point projection directed vertically down.
By itself, such a projection can be used, in particular, for making holes on the same vertical in ceilings located at different levels. It is enough to make one of the holes, install a level above it — and the laser beam going vertically downwards will indicate the location of the next hole. And in devices that also have the zenith function (see above), the marks from the zenith and nadir projections are located strictly one above the other. This is very convenient when marking the floor and ceiling at the same time for racks, partitions, etc.
Operating time
Operating time of the device on one battery charge.
It is worth considering that these figures are quite approximate, since the operating time is measured under certain standard conditions (usually continuous operation at nominal power). And since in practice conditions may differ markedly, the operating time may turn out to be noticeably shorter or longer than stated. In addition, if the device uses replaceable batteries (AAA, AA and the like), then autonomy will also depend on the quality of the specific batteries/accumulators. Nevertheless, based on the data specified in the characteristics, it is quite possible to evaluate the capabilities of specific models and compare them with each other: the difference in the declared operating time, as a rule, proportionally corresponds to the difference in practical autonomy under the same conditions.
We also note that the operating time is specified mainly for levels; in rangefinders another parameter is more often used - the number of measurements (see below).
