Using Laser Distance Finders

By: Brian Rhodes, Published on Jun 04, 2012

Calculating correct distances can be a pain but are an essential part of properly estimated projects. For years, the tape measure has been a constant companion on site surveys, but even the simple task of taking measurements can be a time consuming, two man job - especially for longer distances. Does a better alternative exist? In this note we review laser distance meters, a simple handtool that we have found to be a great alternative to tape measures when taking measurements in the field.

Overview

The time it takes light to travel can be used to calculate distance. The longer it takes for a laser to bounce off of a remote target and return to the sending point, the farther away the target is located.

Laser distance finders, or 'rangefinders' are handheld, battery powered devices that use this principle to measure distance. These units emit a low power laser matched to a sensitive collector that measures minute amounts of reflected light. A very precise timer measures this loop many thousands of times in a second, and the time value is converted to read as a distance measure on the meter's display.

Common Features

While a wide variety of models exist, features common to most units can also be found in the example below:

Features like extended measurement distance (lengths exceeding 650' are common), area measurements, memory capacity, and enclosure durability all influence final cost. However, for most security installers the basic, most inexpensive models are sufficient.

Analysis

Pros

Get Notified of Video Surveillance Breaking News
Get Notified of Video Surveillance Breaking News

Quick: The speed that measurements are taken might be the biggest advantage of laser distance finders. When compared with the process of unreeling measuring tape, stepping off a distance with a wheel, or counting ceiling tiles, the laser unit is almost instantaneous. The term 'point and shoot' is often used to describe the process required to collect a measurement, and several measurements covering hundreds of feet can be taken in a minute or less.

Lightweight and small: The physical dimensions of a distance finder are small, approximately the same size as a multimeter. Devices can be easily carried on belt clips or in tool bags, and can be operated using only one hand.

Inexpensive: Laser distance finders can be purchased for under $100, and while more expensive than traditional tape measures, models are not so expensive they cannot be purchased as a common hand tool.

Accurate enough for most measurements: Early versions of laser distance finders were prone to being wildly inaccurate, but current models are accurate and precise to fractions of an inch. For example, this 650' distance model is accurate to +/- 0.04 inches at maximum measured length. The more significant concern for modern models is angularity error the operator introduces in holding the unit 'off-target'. In any case, for the rather coarse measurements taken during a site survey, the laser distance finder is sufficient for most video security work.

Cons

Hard to see in bright sunlight: The most common complaint of using laser distance finders are that finding the 'laser dot' can be difficult in brightly lit areas. While the ambient brightness and reflectivity do not affect the accuracy of the tool, it is easy to lose the dot location in sunlight flooded areas. A variety of tools exist to help reduce this problem, including 'laser enhancement glasses' that make the dot appear more intense in sunlight.

Hard to see at extreme distances: Along with brightness, successfully locating a 'laser dot' at extreme lengths can be difficult. The diameter of the laser dot is often 1/4" or less, and over hundreds of feet it can be very difficult to locate. Some 'high end' distance finders include a built-in camera with zoom [link no longer available] to help with this. Some users may opt to fabricate a 'target', like we demonstrate in the video below, that simply provides a dark, high contrast target to bounce a beam from in the field.

Humidity, heat can affect accuracy: While modern units have been engineered to overcome the weaknesses of early models, certain environmental situations can affect unit performance. For example, heat influences beam divergence (expanding beam diameter) over distance and can distort the timing of beam travel. While this distortion may be an extremely minute amount,even  a small visual disturbance can result in a significant distance error. Likewise, high humidity (the presence of moisture in the air) not seen with the naked eye can sometimes contains enough water vapor to introduce meter error. The best approach to take to prevent these errors are to read the unit manual and apply the meter only within environment parameters defined by the manufacturer.

Not all units are create equal: As with any manufactured device, the quality of components affect usability. Modern units are built with 'pulsed emitters' designed to minimize measurement error, but older 'fixed emitter' technology is still used in lower-cost alternatives. Because 'laser distance finder' is a generic term, care should be taken to select a unit with a proven history of use. This risk is often most significant when specifying units with extreme maximum distances (>800 feet) and multi-function units (Ultrasonic stud finder/laser distance finder combos) Fortunately, units built with good technology can be found even at the low-end of pricing. Simply reading product reviews on these units can go a long way in choosing the right unit.

Demonstration Video

Here is a quick video that introduces this tool and shows basic operation. While exact operation may vary from unit to unit, the function below is common to most tools in the category:

The measuring wheel is the most common alternative to laser meters. In a future post, we will review measuring wheels and compare.

Comments : Members only. Login. or Join.

Related Reports

Installation Course January 2020 - Last Chance on Jan 16, 2020
Thursday, January 16th is your last chance to register for the Winter 2020 Video Surveillance Installation Course. This is a unique installation...
IP Camera Installability Shootout 2019 - Avigilon, Axis, Bosch, Dahua, Hanwha, Hikvision, Uniview, Vivotek on Dec 09, 2019
What are the best and worst cameras to install? Which manufacturers make it the hardest or easiest to install their cameras? We tested 35 total...
Access Startup Multi-Mount Aims To Streamline Reader Installs on Dec 03, 2019
Startup Multi-Mount claims it makes installing access readers 'Fast', 'Secure,' and fit 'any size frame.' The company states its bracket 'fits most...
Hidden Camera Detectors Tested on Nov 18, 2019
Hidden cameras are a growing problem as cameras become smaller, cheaper and easier to access. However, some companies claim to be able to detect...
Camera Cable Whip Guide on Oct 02, 2019
Cable whips are one of integrator's least favorite camera features but seem to be unavoidable, now commonplace on dome, turret, and bullet cameras...
Lasers Impact on Surveillance Cameras Tested on Sep 25, 2019
Hong Kong protests have brought global attention to video surveillance and the ongoing attempts of protesters to disable or undermine those cameras...
How To See If Your Camera Uses Huawei Hisilicon Chips on Aug 30, 2019
Rarely do manufacturers disclose what SoCs (System on a Chip) they use, even though it is the core of IoT devices. Interest in this has increased...
Riser vs Plenum Cabling Explained on Apr 18, 2019
You could be spending twice as much for cable as you need. The difference between 'plenum' rated cable and 'riser' rated cable is subtle, but the...
Pole Mount Camera Installation Guide on Apr 11, 2019
Poles are a popular but challenging choice for deploying surveillance cameras outdoors. Poles are indispensable for putting cameras at the right...
Outdoor Camera Installation Guide on Mar 25, 2019
Outdoor camera installation can be fraught with problems. Creating a sturdy and weather tight mount is key for camera performance and longevity,...

Most Recent Industry Reports

FLIR New Coronavirus Prioritized Temperature Screening Camera Examined on Apr 03, 2020
FLIR has announced a new series of thermal cameras "prioritized for entities working to mitigate the spread of COVID-19 virus", the A400/A700...
ADI Branch Burglary on Apr 03, 2020
A security systems distributor branch is an odd target for burglary but that happened this week at ADI's Memphis location. Vehicle Smash &...
Hikvision And Dahua Now Blocked From Conforming ONVIF Products on Apr 03, 2020
Dahua and Hikvision, sanctioned for human rights abuses, are now blocked from submitting products for ONVIF conformance, a blow to the mega China...
YCombinator AI Startup Visual One Tested on Apr 02, 2020
Startup Visual One, backed by Silicon Valley's powerful Y Combinator, aims to be "Your 24/7 Watchman" with advanced analytics and object...
Free IPVM Memberships For The Unemployed on Apr 02, 2020
IPVM is giving 3-month free memberships (regular price $99) for the unemployed, no questions asked. To get it, just contact us, your request...
Dahua Faked Coronavirus Camera Marketing on Apr 01, 2020
Dahua has conducted a coronavirus camera global marketing campaign centered around a faked detection. Now, Dahua has expanded this to the USA,...
Video Surveillance Trends 101 on Apr 01, 2020
This report examines major industry factors and how they could impact video surveillance in the next 5 - 10 years. This is part of our Video...
USA's Seek Scan Thermal Temperature System Examined on Apr 01, 2020
This US company, Seek, located down the road from FLIR and founded by former FLIR employees is offering a thermal temperature system for the...
Terrible Convergint Coronavirus Thermal Camera Recommendation on Apr 01, 2020
A week after Convergint disclosed falling revenue, pay and job cuts, Convergint is touting 'extensive research' that is either grossly incompetent...
The IPVM New Products Online Show April 2020 Opens With 40+ Manufacturers on Mar 31, 2020
IPVM is excited to announce the first New Products Online show, with 40+ manufacturers, to be held April 14 to the 16th, free to IPVM members,...