MODEL SR540
OPTICAL CHOPPER
MODEL SR540
OPTICAL CHOPPER
Copyright © 1986, 1988, 1995, 1997
Stanford Research Systems, Inc.
All Rights Reserved
Rev. 2.4
Stanford Research Systems, Inc.
1290-D Reamwood Ave.
Sunnyvale, CA 94089 USA
(408) 744-9040
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TABLE OF CONTENTS
Symbols used
Specifications
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Safety & Preparation for Use
Quick Start Instructions
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Operating Instructions
Introduction ……………………………………………………………
Frequency of Operation ………………………………………………
Changing Blades ……………………………………………………….
Baseplate Removal …………………………………………………….
Applications
Single Beam …………………………………………………………...
Single Beam Chopping to 20 kHz ……………………………………..
Dual Beam Experiments ……………………………………………….
Detection at Sum & Difference Frequencies …………………………..
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Variable Aperture ……………………………………………………...
Calibration
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Circuit Description
Motor Speed Control …………………………………………………..
Optical Pick-Offs ………………………………………………………
Frequency Synthesis …………………………………………………...
Frequency Display ……………………………………………………..
Power Supplies ………………………………………………………...
Parts List
PC Layout
Schematic
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SPECIFICATIONS
Chop Frequency 4 Hz to 400 Hz with 6 slot blade.
400 Hz to 3.7 kHz with 30 slot blade.
Frequency Stability 250 ppm/°C typical.
Long Term Frequency Drift < 2%, 100 Hz < f < 3700 Hz
Phase Jitter 0.2° rms from 50 Hz to 400 Hz.
0.5° rms from 400 Hz to 3.7 kHz.
Frequency Display 4 digit, 1 Hz resolution, 1 Hz accuracy.
Frequency Control 10 turn pot with 3 ranges:
4 Hz to 40 Hz
40 Hz to 400 Hz
400 Hz to 3.7 kHz
VCO 0 to 10 VDC. Control voltage overrides frequency dial.
Reference Modes Switch Left BNC Right BNC
up ƒ
inner
ƒ
middle 5 x ƒ ƒ
down ƒ + ƒ
inner
ƒ – ƒ
inner
Dimensions Controller 7.7" x 5.1" x 1.8"
Chopper Head 2.8" x 2.1" x 1.0"
Blade Diameter 4.00"
Power 100 / 120 / 220 / 240 VAC
50 / 60 Hz
12 Watts
Warranty Electronics - One year parts and labor on materials and
workmanship.
Chopper Motor - Ninety days parts and labor on materials and
workmanship.
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************ CAUTION ************
LINE FUSE
This instrument may be damaged if operated
with the LINE VOLTAGE SELECTOR set for
the wrong ac input-source voltage or if the
wrong fuse is installed.
LINE VOLTAGE SELECTION
The SR540 operates from a 100V, 120V, 220V,
or 240V nominal ac power source having a line
frequency of 50 or 60 Hz. Before connecting
the power cord to a power source, verify that the
LINE VOLTAGE SELECTOR card, located in
the rear panel fuse holder, is set so that the
correct ac input voltage value is visible
(figure 1).
To Change Voltage Selected: Open the cover on
the power entry module using a small
screwdriver; pull the voltage selector card
straight out using long-nose pliers; orient
selector card so that the desired voltage is
readable at the bottom; orient the indicator pin
to point up when desired voltage is readable at
the bottom (figure 2); insert voltage selector
card into housing, printed side facing left, and
edge containing desired voltage first; replace
cover and verify that the indicator pin shows the
desired voltage.
Verify that the correct line fuse is installed
before connecting the line cord. For 100V and
120V, use a 1/4 Amp fuse and for 220V and
240V, use a 1/8 Amp fuse.
LINE CORD
This instrument has a detachable, three-wire
power cord with a three-contact plug for
connection to both the power source and
protective ground. The protective ground
contact connects to the accessible metal parts of
the instrument. To prevent electrical shock,
always use a power source outlet that has a
properly grounded protective-ground contact.
OPERATE ONLY WITH COVERS IN
PLACE
To avoid personal injury, do not remove the
product covers or panels. Do not operate the
product without all covers and panels in place.
KEEP HANDS CLEAR OF CHOPPER
BLADE
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