Extech Instruments LT45 User manual

User Manual
LED Light Meter
Model LT45
www. .com [e-mail]1.800.561.8187

2 LT45-en-US_V2.1 6/20
Introduction
Congratulations on your purchase of the Extech LT45 LED Light Meter that measures light from LED
lamps in addition to fluorescent, metal halide, high-pressure sodium and incandescent sources. The
LT45 is capable of measuring the illumination of white, red, yellow, green, and blue LEDs up to
400,000 Lux (40,000 Fc).
The LT45 can also calculate luminous intensity (CD) using a distance-to-the-light value programmed
by the user in meters or feet units.
The LT45 can store up to 99 readings for later recall and includes Overload indication, Battery status
icon, Data hold, Maximum/Average/Minimum (MAX/MIN) tracking, push-button Zero calibration
adjustment, Auto Power off (with disable function), and auto ranging features.
This instrument is shipped fully tested and calibrated and, with proper use, will provide years of
reliable service. Please visit our website to check for the latest version of this
User Guide, Product Updates, and Customer Support.
Features
Overload Indication: LCD screen at the upper left-hand corner
Battery strength status indication
Display Update Rate: 2.5 times per second
Spectral response near CIE luminous spectral efficiency ratings
Cosine Angle corrected
Conforms to JIS C 1609:1993 and CNS 5119 general class A Specifications
Measures the intensity of illumination of white, red, yellow, green, and blue LED light and
visible light in Lux or foot-candles
Calculates Luminous Intensity (CD)
Data hold freezes displayed reading
Maximum/Average/Minimum Memory Hold
Zero adjustment
Auto power off with disable function
Automatic range adjust optimizes accuracy and resolution
Manually store/recall up to 99 readings
Complete with light sensor, protective sensor cover,
(1.5m), 9V battery, and hard shell case
www. .com [e-mail]1.800.561.8187

3 LT45-en-US_V2.1 6/20
Safety
Do not operate the meter in environments where the following are present: explosive gases
(or materials), combustible gases (or materials), steam, or dust.
Please replace the battery immediately when the battery symbol appears on the LCD.
Do not touch t
could damage the sensitive components.
For Indoor use only. This instrument was designed for pollution degree 2.
Meter Description
1. Display (LCD)
2. Lux/Fc/CD unit select button
3. MEM/READ button (for 99 reading memory)
4. Up arrow button and MAX/MIN/AVG button
5. Power and Auto Power OFF control button
6. Zero Calibration button
7. Data Hold and Light source select button
8. Down arrow button
9. Coiled sensor connection cable
10. Photo detector
Note: The battery and tripod mount are located
on the back of the meter
www. .com [e-mail]1.800.561.8187

4 LT45-en-US_V2.1 6/20
Operation
Power ON-OFF
Momentarily press the Power button to power the meter. To power the meter OFF,
momentarily press the Power button again.
Taking Measurements
1. Switch the meter ON
2. R
switch ON, if not check that fresh batteries are installed.
3. The meter measures the intensity of the light (illuminance) that strikes the sensor dome in
foot candles and lux units (1 fc = 10.76 lux) displaying the measured value on the LCD.
4. Use the LUX/FC/CD button to select Lux or Foot candle units (CD, luminous intensity, is
5. Position the meter and light source so that the light strikes the sensor dome perpendicularly.
6. can show a value up to 3999 on the large digits and when more digits are
needed to represent the reading two additional (smaller) digits appear to the right of the
larger digits, e.g. 399900.
LUX/FC/CD Units
Momentary presses of the LUX/FC/CD button toggles Lux and FC (foot-candles) units. Press and
hold the button to enter the CD (luminous intensity) mode.
for further information.
Auto Power OFF
To save battery life the meter powers down automatically after approximately 5 minutes of
inactivity (no button presses).
Enable/Disable Auto Power Off
With the meter ON, press and hold the Power button until the APO clock symbol switches
OFF (the Auto Power OFF utility is now disabled and the user must manually switch the meter
off). To re-enable the Auto Power OFF utility, repeat this process. The Clock symbol will switch
ON when the Auto Power OFF utility is re-enabled.
Zero Calibration
1. Ensure that the protective cover is attached to the light sensor.
2.
3. Momenarily press and the ADJ (adjusting) icon will switch ON indicating
that the zero adjustment (calibration) is working. When the calibration is finished, the ADJ
icon will switch OFF and the meter will return to the normal operating mode.
4. If the protective cap is not covering the sensor when the ZERO calibration is started the LCD
In this case, please cover the sensor with the cap and restart this
procedure.
www. .com [e-mail]1.800.561.8187

5 LT45-en-US_V2.1 6/20
MAX/AVG/MIN Memory Mode
The meter can record the maximum, minimum, and average readings as described below:
1. Momentarily press the MAX/AVG/MIN button and the meter will begin to track the
indicating that the meter is now displaying the minimum reading. The reading will not
change until a lower reading is registered.
2. Press the
3. Press the
show the average of the readings taken since the
icon will be displayed.
4. Press the
To exit this mode, press and hold the button for at least 2 seconds. The MAX/AVG/MIN icons
should all be switched OFF when the unit returns to the normal operating mode.
Memory Record/Read Mode
1. Momentarily press the Mem/Read button to store a reading. The LCD will display a small M
icon on the lower left-hand area of the LCD along with the memory location number (1 to
99) representing the storage location for the recorded reading. Up to 99 readings can be
stored.
2. To review (read) the stored readings, press and hold the Mem/Read button until the MEM
icon appears at the top of the LCD. Now use the arrow buttons to scroll through the stored
readings. The
lower left-hand corner of the LCD while the main display digits show the stored reading for
the selected memory location.
3. To store an average (AVG) reading, first access the AVG mode (See MIN/MAX/AVG section of
this guide) and while an average reading is displaying (AVG icon switched ON), momentarily
press the Mem/Read button for one second. The LCD will display AVG M and the memory
location number (1 to 99) indicating that an average reading has been stored in the
numbered memory location.
4. When a stored reading is an AVG value, the screen will display AVG on the lower left-hand
corner.
5. Momentarily press the Mem/Read button to exit the Memory mode and return to the
normal operating mode.
6. To clear all 99 memory locations: With the meter switched OFF, press and hold the
Mem/Read and On/Off buttons simultaneously for two seconds. The meter will switch ON
and the screen will display CLr all of the 99 memory locations have been
erased.
Data Hold
Press the Hold button to freeze the displayed reading (the HOLD icon will switch ON). Press the
button again to release the held reading con will switch OFF).
www. .com [e-mail]1.800.561.8187

6 LT45-en-US_V2.1 6/20
Luminous Intensity (CD) Measurements
1. Press the On/Off button to turn power ON.
2. Press and hold the LX/FC/CD s unit designator switches to CD.
3. Use the arrow buttons to select ft (feet) or m (meter) units to represent the distance the
sensor will be from the light source.
4. Momentarily press the LX/FC/CD button; the smaller digits (lower-right hand corner of LCD)
will switch ON, these digits represent the distance to the light source.
5. Use the arrow buttons to set the distance from the center of the lamp to the measurement
base level. Press and hold an arrow button to scroll quickly.
6. Momentarily press the LX/FC/CD button.
7. Remove the protective sensor cap and place the sensor perpendicular to the light at the
programmed distance.
8. Read the Luminous Intensity calculation on display.
9. Press and hold the LX/FC/CD button to exit this mode.
Luminous Intensity = illumination (Lx) x distance (ft2 or m2)
The programmable distance range is 0.01 ~ 30.47 m (0.01 ~ 99.99 ft.)
Light Source (L.S.) Selection
There are 10 light source selections (L0 L9) each having a unique calibration correction factor
(multiplier). See the Light Source list below. The multipliers for locations L0 through L6 are fixed
for the lighting types listed. Locations L7 through L9 are extra locations that the user can
customize (with a multiplier from 0.001 to 1.999). To change the light source (L.S.) selection:
1. Press and hold the Hold/LS button for 2 seconds. The light source code, at the bottom center
of the LCD, will flash. Use the arrow buttons to select L0
(correction factor) will be shown to the right of the Lx value (L8 1000, for example).
2. To customize a location, select L7, L8 or L9 and, once selected, momentarily press the
Hold/LS button to enter the multiplier programming mode. Now use the arrow keys to
change the multiplier. Press and hold an arrow button to scroll faster.
3. When finished, press and hold the Hold/LS button for at least 1 second to confirm the edit
and exit this mode.
Light Source
L0: Standard incandescent light source
L1: LED white daylight
L2: LED AMBER (YELLOW) light
L3: LED GREEN light
L4: LED RED light -
L5: LED BLUE light
L6: Not used
L7~L9: Programmable User Custom Locations (preset to 1.00)
www. .com [e-mail]1.800.561.8187

7 LT45-en-US_V2.1 6/20
Measurement Considerations and User Tips
For maximum accuracy allow the light being measured to fall directly on the sensor as
perpendicular as possible with a minimal angle of incidence.
When the meter is not in use, please keep the protective cap in place, covering the light sensor.
This will prolong the life of the sensor.
When the meter is to be stored for long periods, please remove the battery and store it
Avoid areas of high temperature and humidity when using this instrument.
See Specifications for accuracy with angular deviation.
Battery Replacement and Maintenance
Cleaning and storage
1. The white plastic sensor dome should be cleaned with a damp cloth when necessary. Use
only a mild soap if needed. Do not use solvents, abrasives, or harsh detergents to clean the
dome.
2. Store the meter in an area with moderate temperature and relative humidity.
Battery Replacement
When the battery power decreases to a critical level, the battery symbol will appear as empty on
the LCD. Replace the 9V battery located in the rear battery compartment. The battery
compartment slides easily downward for removal (in the direction of the printed arrow on the
rear of the meter). Ensure that the compartment cover is securely fastened before using the
meter.
Safety: Please dispose of batteries responsibly; never dispose of batteries in a fire, batteries may
explode or leak. If the meter is not to be used for 60 days or more, remove the battery and store
separately.
www. .com [e-mail]1.800.561.8187

8 LT45-en-US_V2.1 6/20
Specifications
Sampling rate 2.5 times per second (digital display)
Display 6-digit LCD with battery icon, measurement overload, and
other function indicators
Sensor (detector) Silicon photodiode with spectral response filter and cosine
correction
Ranges and Resolution
*Above 3999, the LCD uses
smaller digits on the right
side
Lux
Foot
-
candles
399.9 0.1 39.99 0.01
3999 1 399.9 0.1
*39999 10 3999 1
*399999 100 *39999 10
Auto-range The meter automatically ranges the display
Accuracy
(1 Fc = 10.76 Lux)
LED light:
± (3% of reading + 3 digits) up to 500 Lux (46Fc)
± (3% of reading) above 500 Lux (46Fc)
Visible Light:
Calibrated to standard incandescent lamp 2856oK at an
ambient temperature of 23oC
± (6% of Reading + 3 digits)
Angle deviation from cosine
characteristics
(Cosine Angular corrected
per JIS C 1609:1993 and CNS
5119 general A class)
30 ±2%
60 ±6%
80 ±25%
LED Types Meter measures white, red, yellow, green, and blue LED light
Operating conditions Temperature: 41 to 104oF (5 to 40oC); Humidity: < 80% RH
Operation Altitude
Storage Temperature/RH 14 to 140oF (-10 to 60oC); Humidity: < 70% RH
Battery status indication Battery symbol appears empty when battery voltage reaches critical level
Power supply 9V battery
Auto Power OFF Meter powers down after 5 minutes of inactivity (can be defeated)
Dimensions Meter: 38 x 55 x 130mm)
Sensor: 25 x 44 x 80mm)
Cable length: 1.5m)
Weight Approx. 8.8 oz. (250g) with battery installed
www. .com [e-mail]1.800.561.8187

9 LT45-en-US_V2.1 6/20
RELATIVE SENSITIVITY (%)
LT45
www. .com [e-mail]1.800.561.8187

10 LT45-en-US_V2.1 6/20
Two-year Warranty
FLIR Systems, Inc. warrants this Extech brand instrument to be free of defects in parts and workmanship for
two years from date of shipment (a six-month limited warranty applies to sensors and cables). To view the full
warranty text please visit:
Calibration and Repair Services
FLIR Systems, Inc. offers calibration and repair services for the Extech brand products we sell. We
offer NIST traceable calibration for most of our products. Contact us for information on calibration
and repair availability, refer to the contact information below. Annual calibrations should be
performed to verify meter performance and accuracy. Product specifications are subject to change
without notice. Please visit our website for the most up-to-date product information:
.
Copyright ©2014-2020 FLIR Systems, Inc.
All rights reserved including the right of reproduction in whole or in part in any form
www. .com [e-mail]1.800.561.8187