Newport 1825-C User manual

O PERATOR ’ S
M ANUAL
Model 1825-C
Power/Energy Meter

Model 1825-C
Power/Energy Meter

ii
Warranty
Newport Corporation warrants this product to be free from defects in material
and workmanship for a period of 1 year from the date of shipment. If found to
be defective during the warranty period, the product will either be repaired or
replaced at Newport’s option.
To exercise this warranty, write or call your local Newport representative, or
contact Newport headquarters in Irvine, California. You will be given prompt
assistance and return instructions. Send the instrument, transportation
prepaid, to the indicated service facility. Repairs will be made and the instru-
ment returned, transportation prepaid. Repaired products are warranted for
the balance of the original warranty period, or at least 90 days.
Limitation of Warranty
This warranty does not apply to defects resulting from modification or misuse
of any product or part. This warranty also does not apply to fuses, batteries,
or damage from battery leakage.
This warranty is in lieu of all other warranties, expressed or implied, includ-
ing any implied warranty of merchantability or fitness for a particular use.
Newport Corporation shall not be liable for any indirect, special, or conse-
quential damages.
Statement of Calibration
This instrument has been inspected and tested in accordance with specifica-
tions published by Newport Corporation.
The accuracy and calibration of this instrument and photodetector (where
applicable) is traceable to the National Institute for Standards and Technology
through equipment which is calibrated at planned intervals by comparison to
the certified standards maintained at Newport Corporation.
Copyright 1997, Newport Corporation
Part No. 19572-01, Rev. F
IN-04925 (07-97)

iii
VP European Operations General Manager-Precision Systems
Zone Industrielle 1791 Deere Avenue
45340 Beaune-la-Rolande, France Irvine, Ca. USA
We declare that the accompanying product, identified with the
"" mark, meets the intent of the Electromagnetic Compatability
Directive, 89/336/EEC and Low Voltage Directive 73/23/EEC.
Compliance was demonstrated to the following specifications:
EN50081-1 EMISSIONS:
Radiated and conducted emissions per EN55011, Group 1,
Class A
EN50082-1 IMMUNITY:
Electrostatic Discharge per IEC 1000-4-2, severity level 3
Radiated Emission Immunity per IEC 1000-4-3, severity level 2
Fast Burst Transients per IEC 1000-4-4, severity level 3
Surge Immunity per IEC 1000 4-5, severity level 3
IEC SAFETY:
Safety requirements for electrical equipment specified in
IEC 1010-1.
Alain Danielo Jeff Cannon
EC DECLARATION OF CONFORMITY
Active Isolation Module Set Series
Model 1825-C

iv
Table of Contents
Page
Warranty ........................................................................................................... ii
EC Declaration of Conformity ........................................................................ iii
List of Figures .................................................................................................. vi
List of Tables ................................................................................................... vi
Safety Symbols and Terms ............................................................................ vii
General Warnings and Cautions ................................................................... vii
Abbreviations ................................................................................................viii
Specifications................................................................................................... ix
Section 1 – General Information
1.1 System Overview ................................................................................... 1
1.2 Scope of this manual ............................................................................. 1
1.3 Unpacking and Inspection .................................................................... 2
1.4 Preparation for Use ............................................................................... 2
1.5 Optional Accessories and Services ..................................................... 2
Section 2 – System Operation
2.1 Introduction ........................................................................................... 3
2.2 Display .................................................................................................... 3
2.3 Front and Rear Panel Controls ............................................................. 4
2.3.1 RANGE ........................................................................................... 5
2.3.2 ZERO ............................................................................................. 5
2.3.3 AVERAGE ...................................................................................... 6
2.3.4 MODE ............................................................................................ 6
2.3.5 CAL Slide Switch .......................................................................... 6
2.3.6 SETUP Dip Switches .................................................................... 7
2.3.7 EXP. ADJ. Rotary Dip................................................................... 7
2.4 Using the System ................................................................................... 7
2.4.1 Battery Charging ......................................................................... 7
2.4.2 Power Up ...................................................................................... 8
2.4.3 Detector Connection and Setup ................................................ 8
2.4.4 Setting the Detector Calibration Factor ................................... 8
2.4.4.1 Calibration Factor Mantissa Entry ................................... 9
2.4.4.2 Calibration Factor Exponent Entry................................... 9
2.4.5 Signal Averaging .......................................................................... 9
2.4.6 Signal Integration ...................................................................... 10
2.4.7 Peak-to-Peak Power Measurement .......................................... 11
2.4.8 Pulse Energy Measurement...................................................... 11
2.4.9 Detector Acceleration Time Constant .................................... 12
2.4.10 Analog Output ............................................................................ 13

v
Section 3 – Principles of Operation
3.1 Introduction ......................................................................................... 14
3.2 Functional Description ........................................................................ 14
3.3 Measurement Considerations ............................................................ 15
3.3.1 Detector Calibration and Accuracy ........................................ 15
3.3.2 Quantum Detector Temperature Effects ................................ 16
3.3.3 Thermopile Detector Temperature Effects ............................ 16
3.3.4 Energy Detector Temperature Effects .................................... 16
3.3.5 Ambient and Stray Light ........................................................... 16
3.4 Performing Basic Measurements ....................................................... 17
3.4.1 Making a CW Power Measurement ......................................... 17
3.4.2 Making a Signal Integration Measurement ............................. 18
3.4.3 Making a Pulse Energy Measurement ..................................... 18
3.4.4 Common Measurement Errors ................................................ 19
3.5 System Accuracy ................................................................................. 19
Section 4 – Test, Maintenance and Troubleshooting
4.1 Maintenance Procedures .................................................................... 20
4.2 Troubleshooting Guide ....................................................................... 20
Section 5 – Factory Service
5.1 Introduction ......................................................................................... 21
5.2 Obtaining Service................................................................................. 21
5.3 Service Form ......................................................................................... 23

vi
List of Figures
Figure 1 Model 1825-C and Accessories.......................................................... 1
Figure 2 Model 1825-C Display ......................................................................... 4
Figure 3 Model 1825-C Front Panel Detail ....................................................... 5
Figure 4 Model 1825-C Rear Panel Detail ........................................................ 5
Figure 5 Detector Setup Table.......................................................................... 8
Figure 6 Integrated Energy from Exposure to an Optical Power ............... 10
Figure 7 Integrated Energy from a Pulse Energy Optical Source ............... 10
Figure 8 Peak-to-Peak and Other Signal Types............................................. 11
Figure 9 Pulse Signal Detection ...................................................................... 12
Figure 10 Detector Time Constant ACCEL. ADJ. Setting ............................... 13
Figure 11 Simplified Model 1825-C Functional Block Diagram ..................... 14
Figure 12 Typical Energy Detector Signal Waveform .................................... 15
List of Tables
Table 1 Model 1825-C Display Annunciators................................................. 3
Table 2 Model 1825-C Front Panel Controls .................................................. 4
Table 3 MODE Switch Position and Detector Compatibility ....................... 6
Table 4 CAL Slide Switch Functions ............................................................... 6
Table 5 SETUP Dip Switch Functions ............................................................. 7
Table 6 EXP. ADJ. Rotary Dip Switch Settings .............................................. 9
Table 7 Common Measurement Errors ........................................................ 19
Table 8 Symptom/Fault Troubleshooting Guide ........................................ 20

vii
Safety Symbols and Terms
The following safety terms are used in this manual:
The Warning heading in this manual explains dangers that could result
in personal injury or death.
The Caution heading in this manual explains hazards that could damage
the instrument.
In addition, a Note heading gives information to the user that may be
beneficial in the use of this instrument.
General Warnings and Cautions
The following general warnings and cautions are applicable to this instru-
ment:
Warning
This instrument is intended for use by qualified personnel who
recognize shock hazards or laser hazards and are familiar with
safety precautions required to avoid possible injury. Read the
instruction manual thoroughly before using, to become familiar
with the instrument’s operations and capabilities.
Warning
The American National Safety Institute (ANSI) states that a shock
hazard exists when probes or sensors are exposed to voltage levels
greater then 42VDC or 42V peak AC. Do not exceed 42V between
any portion of the Model 1825-C (or any attached detector or
probe) and earth ground or a shock hazard will result.
Caution
There are no user serviceable parts inside the Model 1825-C. Work
performed by persons not authorized by Newport may void the
warranty. For instructions on obtaining warranty repair or service
please refer to section 5 of this manual. Do not operate this unit via
its AC Adaptor without the included rechargeable battery pack
installed. Use only the AC Adapter provided with the Model 1825-
C by Newport.

viii
Abbreviations
A amps
AC alternating current
ADC analog-to-digital converter
BAT battery
BIC biconic fiber connector
BNC standard coaxial connector type
°C degrees Centigrade
DC direct current
°F degrees Fahrenheit
Hz hertz (cycles per second)
I-V current-to-voltage converter
kHz kilohertz
kΩkiloOhms
LSD least significant digit
mA milliamps
mV millivolts
nA nanoamps
nF nanofarads
nm nanometers
P-P peak-to-peak
RH relative humidity
S/N serial number
µA microamps
µs microseconds
V volts
W watts

ix
Specifications
Physical Specifications
Dimensions: 3.75 ×7.5 ×9.25 in. (95 ×191 ×235 mm)
Weight: 5 lb (2.3 kg)
Enclosure: Metal case, painted
Connectors: Signal Input BNC; Signal Output BNC;
Power 2.5 mm Phone Jack
Power: 12 VDC, 200 mA unregulated
Battery Life: 20 hours
Battery Type: Lead acid rechargeable, 1000 cycles
Display: 3.5 digit annunciated LED and analog
meter
Reading Rate: 12 Hz Max.
Range Switch: 12 position, 6 decades of gain
Operating Environment: <90 % RH Noncondensing. 5 to 40°C
Storage Environment: <90 % RH Noncondensing. -25 to 60°C
Compatible Detectors: Low-Power Detectors; Except 818-F-SL and
818-F-IR
High-Power Detectors
Energy Detectors; Except 818J-S10

x
Electrical Specifications:(0)
Position 6
Position 4
Position 2
Position 8
Position 10
Position 12
Position 1
Position 3
Position 5
Position 11
Position 9
Position 7
Range Knob Positions
Range Switch Position 1 & 2 3 & 4 5 & 6 7 & 8 9 & 10 11 & 12
Full scale measurement (divide value by calibration factor mantissa)
Semiconductor 200nA 2µA 20µA 200µA 2mA 20mA(1)
Thermopile 2mV(2) 2mV 20mV 200mV 2V 20V(3)
Pyroelectric 20mV 200mV 2V 20V 200V 2kV(4)
Relative noise factor (peak-to-peak, measured relative to full scale)
Semiconductor 0.2% 0.02% 0.1% 0.01% 0.01% 0.01%
Thermopile 0.03% 0.03% 0.2% 0.02% 0.02% 0.01%
Pyroelectric 0.3% 0.09% 0.2% 0.02% 0.01% 0.01%
Analog Output Bandwidth (7)
Semiconductor 150Hz 150Hz 25kHz 25kHz 150kHz 150kHz
Thermopile 5Hz 5Hz 20kHz 20kHz 100kHz 100kHz
Pyroelectric 75kHz 75kHz 75kHz 75kHz 200kHz 200kHz
Full scale analog output ................ 2V
Analog output drift ........................ <0-2% / 1 hour at constant temperature
Analog output offset ...................... <10mV
Analog output noise(5) .................. <0.1% +relative noise factor ×calibration factor
mantissa(6)
Calibration accuracy ..................... <0.1% +1% / calibration factor mantissa(6)
DC accuracy .................................... <0.2% +calibration accuracy
Analog output accuracy................ <0.3% +DC accuracy
Peak-to-Peak accuracy .................. <0.5% +DC accuracy +analog output noise / 2
Pulse accuracy ............................... <0.5% +DC accuracy +analog output noise / 2
Integration accuracy ..................... <0.7% +DC accuracy +analog output noise / 2
Display resolution.......................... full scale measurement / 2000
Minimum pulse slope .................... 10V / sec
Allowed detector responsivity limits:
Semiconductor .......................... 1 ×102A/W to 1 ×10-8 A/W
Thermopile ................................ 1 ×105V/W to 1 ×10-5 V/W
Pyroelectric ............................... 1 ×107V/J to 1 ×10-3 V/J
(0) Guaranteed after 30 min. warm up period.
(1) Maximum measurable current is 10mA.
(2) In Thermopile mode, ranges 1 & 2 are identical to 3 & 4.
(3) Maximum measurable voltage in Thermopile mode is 2V.
(4) Maximum measurable voltage in Pyroelectric is 200V.
(5) Measured with 818-SL, 818T-10 or 818J-25 detector, respectively.
(6) Calibration factor mantissa range is 1to 10.
(7) Amplifier bandwidths are higher internally.

1
1.1 System Overview
Section 1
GeneralInformation
The Model 1825-C is an accurate and flexible optical power and energy mea-
suring instrument that provides features typically found only on advanced
single purpose optical meters: Simple front panel controls, annunciated digital
and analog displays, and compatibility with Newport’s full line of detector
families allow the Model 1825-C to meet almost any DC, AC peak-to-peak,
pulsed or integrated exposure measurement requirement with minimum fuss.
Compatible with Newport’s Low-Power, High-Power, and Energy detector
families, the Model 1825-C provides the features you need without the expense
of purchasing multiple single purpose optical meters. The Model 1825-C
Power/Energy Meter and its accessories are presented in Figure 1. Section 1.5
of this manual presents a brief description of compatible Newport detectors.
818-UV
818-SL
818-IR
818-FA 818-
FA2
FP3-CA1
FP3-CA2
FP3-CA3
FP3-CA4
FP3-CA5
FP3-CA6
FP3-FH1
818J-25Q
818J-50Q
818JA-YAG25
818JA-YAG50
818JA-NG254
818JA-NG504
818JA-NG251
818JA-NG504
818JA-9Q
818J-09
818J-09B
818J-25
818J-25B
818J-50
818J-50B
818-ST
818T-10
818T-10V
818T-30
818T-30V
818T-150
818T-150X
818T-300
HIGH-POWER ENERGY LOW-POWER
Needle Acc.±2% FS
Figure 1 — Model 1825-C and Accessories
Please carefully read this instruction manual before using the Model 1825-C
Power/Energy Meter. Be especially careful to observe the warnings and
cautions throughout this manual. If any operating instructions are not clear,
contact Newport Corporation.
This instruction manual contains the necessary information for operation and
maintenance of the Newport Model 1825-C Power/Energy Meter as well as
information for troubleshooting and obtaining service if necessary. This
information is divided into the following sections:
• Section 1 provides general information about this manual and the
Model 1825-C.
• Section 2 explains System Operation procedures for the Model 1825-C
and accessories.
Scope of this manual
1.2

2
• Section 3 discusses the Principles of Operation of the Model 1825-C.
• Section 4 provides for Test, Maintenance and Adjustment of the Model
1825-C.
• Section 5 provides instructions for obtaining factory service.
All Model 1825-C Power/Energy Meters are carefully assembled, tested and
inspected before shipment. Upon receiving this instrument, check for any
obvious signs of physical damage that might have occurred during shipment.
Report any such damage to the shipping agent immediately. Retain the
original packing materials in case reshipment becomes necessary.
The Model 1825-C Power/Energy Meter should have some operations per-
formed before measurements are made. These include:
• Charging the batteries (Section 2.4.1)
• Connection and calibration of the detector (Section 2.4.4)
Many detectors and detector accessories are available for use with the Model
1825-C Power/Energy Meter. In addition, detector accessories are available.
Refer to Figure 1 for the Model 1825-C Power/Energy Meter family tree. For
more information, please refer to the Newport Catalog.
Unpacking and
Inspection
1.3
Preparation for Use
1.4
Optional Accessories
and Services
1.5

3
Section 2
SystemOperation
This section contains the information needed to prepare and operate the
Model 1825-C Power/Energy Meter. Operation consists of using the Model
1825-C to perform basic optical power or energy measurements using one of
Newport’s compatible detectors.
The Model 1825-C combines a fast response 3.5 inch analog display with a 3.5
digit annunciated LED display, see Figure 2. The full scale reading of the
analog display alternates between 2 and 5 as the RANGE knob is rotated so
that it can display signals below 2.00 with higher resolution. The analog
display matches the digital display (within ±1 division typ.) and the annuncia-
tors always indicate the current measurement units. The digital display is
more accurate than the analog display.
To facilitate measurements of integrated, AC peak-to-peak or pulsed signals,
both the analog and digital displays hold their last value for about 20 seconds
before falling back to zero. If a new signal arrives before the display has reset
itself to zero, the new signal is acquired and displayed.
The BAT annunciator lights when the battery voltage reaches 7 volts and
indicates that recharging is needed. See Section 2.4.1, Battery Charging. To
increase battery life, the digital display dims while the analog display backlight
brightens as ambient light levels decrease. Avoid prolonged operation when
the BAT annunciator is lit, measurement accuracy can degrade. The batteries
are protected from deep discharge damage and will automatically disconnect
when they are discharged below 6V.
If one needs to operate the meter even after the battery discharge protection
is activated, there is no need for waiting for batteries to be charged up. You
can operate the 1825-C as soon as the charger is plugged into it.
Table 1 — Model 1825-C Display Annunciators
Annunciator Comment
BAT Battery voltage has reached 7 volts
(approx. 10% battery life left).
CAL Indicates that the Calibration Factor decimal
number is being displayed
TRIG Indicates that a signal has crossed the
threshold that triggers the meter to take a
reading, (INTG, PULSE and peak-to-peak
modes).
READ Indicates that the meter is showing a valid
reading.
W, J Watt and Joule units annunciators,
respectively.
n, µ, m, k Exponent prefixes for the Watt and Joule
annunciators.
Display
2.2
Introduction
2.1

4
BATTRIG
READ
1
2
4
1
.5 1.5
3
02
5
CAL
n
m
k
W
J
Needle Acc.±2% FS
Figure 2 — Model 1825-C Display
Operating controls and settings for the Model 1825-C are found on both the
front and rear panels. For general operation, only the front panel controls are
used. The rear panel controls and settings are primarily used for meter/
detector setup. The front panels of the Model 1825-C are shown in Figure 3.
The following table gives a short description of each control:
Table 2 — Model 1825-C Controls
Control Description Comment
POWER Push Button Turns the Model 1825-C on and off
Meter Adjust 1 Turn Trim Pot Unlabeled. Calibrates the analog
needle zero, (factory set).
CAL 10 Turn Pot Sets the Calibration Factor decimal
number.
ZERO 10 Turn Knob Zeros the display. Used to elimi-
nate ambient signals and elec-
tronic offsets.
AVERAGE 1 Turn Click-Off Knob Turns on and adjusts PULSE/P-P
averaging time.
RANGE 12 Position Knob Adjusts the meter’s signal gain, 12
positions, 6 decades.
MODE 3 Position Knob Sets the meters signal measure-
ment mode: CW, INTEGRATE or
PULSE/P-P.
CAL Slide Switch Selects between CAL, NORMAL
and BEEP operation.
SETUP 8 Switch Dip Bank Configures the meter to the type of
detector being used.
EXP. ADJ. Rotary Dip Switch Sets the Calibration Factor expo-
nent.
ACCEL. ADJ. 10 Turn Trim Pot Sets the thermopile acceleration
time constant.
Front and Rear
Panel Controls
2.3

5
AVERAGE
POWER
OFF MAX
ZERO
CAL
RANGE
CW
MODE
INTEGRATE
PULSE
P-P
■
Power/Energy Meter
■
Model 1825-C
BATTRIG
READ
1
2
4
1
.5 1.5
3
02
5
CAL
n
m
k
W
J
(I)
(O)
ON
OFF
Needle Acc.±2% FS
Figure 3 — Model 1825-C Front Panel Detail
ANALOG
OUTPUT
1
0
INPUT
CAL
BEEP
ON
BEEP
OFF
NORMAL ACCEL
ADJ
EXP
ADJ
O
N
1 2 3 4 5 6 7 8
12 –18V
—-
- - -
LOW-POWER, (SEMICONDUCTOR)
HIGH-POWER, (THERMOPILE)
ENERGY 1 MΩ, (PYROELECTRIC)
ENERGY 50 Ω, (PYROELECTRIC)
PROCESSED OUTPUT
UNPROCESSED OUTPUT
ACCELERATED
NOT ACCELERATED
-
-
1 0 0 0 0 0
0 0 1 1 0 0
0 0 1 0 1 1
0 1 1 0 1 1
- -
- -
- -
- -
1
0
1
0
Figure 4 — Model 1825-C Rear Panel Detail
2.3.1 RANGE
The RANGE knob adjusts the signal gain of the Model 1825-C. It has twelve
positions covering 6 decades of signal gain. Intermediate gain positions only
change the full scale reading of the analog display and do not effect either the
digital display or the analog output. Turn the RANGE knob clockwise (counter
clockwise) to decrease (increase) signal gain. The RANGE positions 1 thru 12
with position 1 being the furthest CCW postion, are illustrated in the figure on
page ix.
2.3.2 ZERO
This knob will adjust the display and analog output values down to zero. It is
used to zero the display to remove the effects of ambient signals before
making a measurement. The ZERO function has the capability of offsetting
signals over a 5 decade range. Turn the ZERO knob CW to decrease the
negative (offsetting) signal that is injected.
Always use the ZERO knob to eliminate ambient and/or offset signals to insure
accurate readings.

6
2.3.3 AVERAGE
This front panel knob adjusts the PULSE/P-P signal averaging of the Model
1825-C’s display and analog output between off and maximum averaging. Use
this knob to slow down the response of the display when observing noisy
signals. A soft detent indicates the signal averaging “off” position. Averaging
only works in INTEGRATE and PULSE/P-P modes.
2.3.4 MODE
The front panel MODE knob sets the method of signal acquisition that the
Model 1825-C will use with a given detector. Not every mode can be used with
every detector. Table 3, below, indicates which modes are compatible with
the various Newport detector types.
Table 3 — MODE Switch Position and Detector Compatibility
MODE Position Compatible Detectors Comment
CW Low-Power, High-Power Measures average optical
power.
INTEG Low-Power,High-Power Measures energy resulting
from integrated power.
P-P†Low-Power Measurespeak-to-peak
optical power.
PULSE†Energy Measures pulse energy.
†While P-P and PULSE are the same position on the MODE switch, the meter’s
operation will differ due to the settings of the SETUP dip switches for the
different detector types. See Section 2.3.6.
2.3.5 CAL Slide Switch
The rear panel CAL slide switch performs the functions described in the table
below:
Table 4 — CAL Slide Switch Functions
Switch Position Function
CAL Display the Calibration Factor mantissa.
NORMAL, BEEP OFF Take readings normally.
NORMAL, BEEP ON Take readings normally but beep with each
pulse triggering. (INTEGRATE & PULSE/P-P
modes only)

7
2.3.6 SETUP Dip Switches
The rear panel SETUP dip switches configure the meter to the type of Newport
detector that the meter will be used with. The following table identifies the
function each SETUP switch position performs:
Table 5 — SETUP Dip Switch Functions
SETUP Switch Switch Position Function
1 Selects current amplification (1) other-
wise (0).
2 Selects voltage amplification (1) other-
wise (0).
3 Selects 50Ω(1) or 1 MΩ(0) voltage
input impedance for Energy detectors.
4 Selects for the type of detector; High-
Power (1) otherwise (0).
5&6 Selects for the type of detector; Energy
(11) otherwise (00).
7 Selects processed analog output (1) or
unprocessed output (0).
8 Selects accelerated voltage response (1)
or unaccelerated response (0).
2.3.7 EXP. ADJ. Rotary Dip
The rear panel EXP. ADJ. rotary dip adjusts the display annunciator units to
properly account for the sensitivity of a detector’s calibration factor exponent.
This allows the display to adjust between different detectors even when the
responsivities of the two detectors may differ by many decades.
The Model 1825-C Power/Energy Meter does not have a microprocessor. It
relies on the user to properly install the calibration factor describing the
detector and wavelength in use. In order to assure that measurements are
accurately calibrated, please carefully read and follow the instructions regard-
ing the Detector Calibration Factor. See Sections 2.4.4, 2.4.4.1 and 2.4.4.2.
2.4.1 Battery Charging
The lead-acid battery pack in the Model 1825-C is designed to provide many
years of reliable operation before any need of replacement. The battery pack
can be recharged by the AC Adaptor at any time and may be charged indefi-
nitely without damage. The batteries will not discharge through the adaptor if
power is removed. With the meter off, a full charge will be reached after 15
hours. With the meter on, the wall mount power supply will trickle charge the
batteries. If you keep the Model 1825-C continuously connected to wall power,
then it will always have a full charge ready for any portable use measurements.
1. Turn the Model 1825-C off and insert the charging plug into the rear
panel 12V DC input.
2. Plug the AC adaptor into the wall. You may now turn the Model 1825-C
back on.
O
N
1 2 3 4 5 6 7 8
1
0
Using the System
2.4

8
NOTE
The battery pack is capable of 1000 to 2000 charge/discharge cycles
before factory replacement is needed. If the battery is continuously
charged, no charge/discharge cycles are accumulated.
NOTE
Prolonged operation after the BAT annunciator lights can cause
inaccurate measurements. Eventually the meter disconnects the
batteries to prevent deep discharge damage.
2.4.2 Power Up
Turn on the Model 1825-C by depressing the POWER button located on the
front of the meter. The digital display should light indicating that the meter is
operating. If the BAT annunciator is lit, operate the meter from the AC adaptor
so the batteries can recharge. See Section 2.4.1.
2.4.3 Detector Connection and Setup
Connect the detector to the INPUT BNC found on the rear of the Model 1825-C.
You may connect or disconnect any Newport Low-Power, High-Power or
Energy detector at any time without damage. Adjust the SETUP dip switches
to reflect the type of Newport detector that the Model 1825-C is being used
with. If you are not using a Newport detector, follow the figure below when
setting up the Model 1825-C. Information from this figure is reproduced on the
rear panel of the Model 1825-C, see Figure 4.
1
0
O
N
1 2 3 4 5 6 7 8
LOW-POWER, (SEMICONDUCTOR)
HIGH-POWER, (THERMOPILE)
ENERGY 1 M
Ω , (PYROELECTRIC)
ENERGY 50
Ω , (PYROELECTRIC)
PROCESSED OUTPUT
UNPROCESSED OUTPUT
ACCELERATED
NOT ACCELERATED
-
-
1 0 0 0 0 0
0 0 1 1 0 0
0 0 1 0 1 1
0 1 1 0 1 1
- -
- -
- -
- -
1
0
1
0
Figure 5 — Detector Setup Table
When using a Newport ENERGY ( or pyroelectric) detector check the detector
manual to determine if it should be operated with 50Ωor 1MΩinput imped-
ance.
We recommend operating with UNPROCESSED OUTPUT and NOT ACCELER-
ATED until you have read the manual sections explaining these features.
2.4.4 Setting the Detector Calibration Factor
The calibration factor tells the Model 1825-C how to account for a detector’s
responsivity at the measurement wavelength. Each Newport detector arrives
with a full spectrum calibration report with detector responsivities and

9
calibration factors listed in 10 nm increments. A calibration factor is calcu-
lated from a responsivity by simply taking the inverse of the responsivity and
expressing it in scientific notation, i.e. “d.ddE±d”. Be sure to re-express the
responsivity value in units of A/W or V/W before calculating the inverse. See
Examples below.
Example 1: Responsivity R = 0.568 A/W thus the Calibration Factor =
1.76 E+0 W/A
Example 2: Responsivity R = 0.346 mV/W thus the Calibration Factor =
2.89 E+3 W/V
2.4.4.1 Calibration Factor Mantissa Entry
The calibration factor mantissa is the “d.dd” portion of the calibration factor
value “d.ddE±d”. The mantissa is the most frequent calibration adjustment
made when making measurements at various wavelengths. To set the man-
tissa, use the following procedure:
1. Slide the CAL switch to the CAL position.
2. Adjust the front panel CAL potentiometer until the display matches the
calibration factor mantissa.
Example: If the Calibration Factor = 2.89 E+3, then the display should
indicate 2.89.
3. Return the CAL switch to the NORMAL, BEEP OFF (or NORMAL, BEEP
ON) position.
2.4.4.2 Calibration Factor Exponent Entry
The calibration factor exponent is the ±d of the calibration factor value
d.ddE±d. The Model 1825-C accounts for this exponent through its EXP. ADJ.
rotary dip setting. The EXP. ADJ. rarely needs to be set more than once when
using the Model 1825-C with a particular detector. However, it is still wise to
check that the EXP. ADJ. does not need resetting when making measurements
at multiple wavelengths. To set the EXP. ADJ. rotary dip, use the following
lookup table:
Table 6 — EXP. ADJ Rotary Dip Switch Settings
Calibration Factor Exponent -7-6-5-4-3-2-101234567
Low Power Detectors –––––0123456789
High Power Detectors ––0123456789–––
Energy Detectors 0123456789–––––
2.4.5 Signal Averaging
The Model 1825-C provides an adjustable low pass filter for signal averaging in
INTEG and PULSE/P-P modes. The effects of averaging cause the display to
slow down its response to changes in signal level. Average feature is disabled
in CW mode. It could be very useful when trying to observe noisy signals, or
signals whose value fluctuates when in PULSE or Peak-to-Peak mode. If
averaging is used in the INTEG mode, accuracy can be lost. We suggest
checking that the use of averaging does not effect the INTEG result in each
measurementsituation.
EXP. ADJ.
Dip Setting