conoptics 302A User manual

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
M302A OPERATING MANUAL
Product Overview:
The Model 302A amplifier is designed to drive a number of different Conoptics E.O. modulators
350, 360 and 370 series. All types of modulators supplied with the system are configured as
lumped capacitors (two terminal devices). The amplifier has a 50/1K ohm, single ended input
(J3 SIGNAL INPUT) and a push/pull output (J1 & J2).
Special Notes:
Special instructions for Model 302A with Model 350-160 for Thorlabs
1. The Model 350-160-02-BK is very close to “0” volts null when operating between
crossed polarizer’s
2. The Model 302A when set for “Uni-Polar Positive” input automatically puts 175Volts
across the modulators terminals
3. Do No Adjust the Bias for “0”. Adjust the Bias Meter Voltage to +175Volts, which should
then yield close to zero volts across the modulator

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
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CAUTION: BEFORE APPLYING POWER
Please review this manual and become familiar with all safety markings and instructions.
Insure that the equipment mains (line) voltage as specified on the rear panel is in accordance
with desired AC source. Safe operation of this equipment may be jeopardized by use other
than specified by Conoptics.
INTENDED USE
This equipment is designed for general laboratory use. It is intended to be used with a number
of Conoptics Electro-Optic Modulators only. The amplifier is designed to drive a capacitive load
that is floating with respect to ground. Any use other than in direct connection with supplied
optical modulator can result in severe damage to the amplifier and potentially hazardous
voltages to external equipment and personnel. This amplifier must only be used in accordance
with the detailed instructions provided in the manual.
WARNING: HAZARDOUS VOLTAGES
Hazardous AC and DC voltages are present on the center pins of the BNC connectors on the rear
panel marked J1 and J2 “AMPLIFIER OUTPUT”. No attempt should be made to come into
contact with these pins or to attempt to verify operation of the amplifier by monitoring these
connectors with an oscilloscope or other test equipment. In addition, the equipment should be
turned off before any of the supplied cables are connected to or disconnected from the driver or
modulator.

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
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SAFTEY GROUND
This equipment is equipped with a protective earth terminal. This terminal is provided by a
common or ground wire in the power cord. The main power source must supply an
uninterrupted return to an earth ground. The equipment must not be used if this earth return is
not supplied.
SERVICE CAUTION
Only qualified personnel must perform adjustment, maintenance, or repair of the equipment.
Hazardous voltages are present within the instrument and contact may result in personal injury.
Any attempt to trouble shoot or adjust any controls within the system should be discussed with
Conoptics first at [email protected]om.

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
4
Model 302A Driver Specifications
Typical Applications
Driver for 360 LTA Series Phase & Intensity Modulators
Driver for Model 370 ADP Series Phase & Intensity Modulators
Driver for Model 380/390 ADP Series Modulators
Driver for Model 310A Beam Deflector
Key features:
Input Requirement:
2 Volts p-p
Input Impedance:
50 ohm
Output Voltage:
350 Volts p-p
-3db Bandwidth:
1.0 MHz with 90pf load
dc bias:
+/- 450 Volts
Driver Cabinet:
6.5” W x 4.125” L x 4.15: H
Power Supply:
19” Rack x 5.25” H

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
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Model 302 Theory of Operation:
The amplifier is DC coupled and is capable of putting out a maximum of 400 Volts Peak-to-Peak
into a capacitive load. The bandwidth of the amplifier is limited by load capacitance, but typical
response times of 400nm (Trand Tf ) are obtainable with load capacitance of 90pf or less. The
high voltage output is obtained by two high power operational amplifiers, operating push-pull.
One operating in the inverting connection, while the other operating non-inverting.
Amplifiers U1and U2are the output drive amps. Each has a supply rail of +/- 140V. U2is
operating non-inverting, and U1 is inverting. They are driven by a single high speed op-amp, U4 .
The output amps run at a forward gain of 100, thus delivering a total forward gain of 200v/v.
U10 and U5 are used to regenerate the “tweeker pulses” derived by the sampled auto bias servo
card in the power supply electronics when the system is configured with this option. In order to
obtain the maximum dynamic range out of the amplifier, some method must be employed to
account for differing types of video input formats, for example:
1. Bipolar, (+/- 1v about gnd)
2. Unipolar pos. or Unipolar neg.
If the output amplifier’s output voltage were zero volts for zero volts in, then each amplifier
would be cable of taking +/- 1 volt at it input, amplifying it to +/- 100v without going into
saturation because of the power supply rails. If the input signal were set to Unipolar (0V to +2V)
and the output amplifies were zero volts out for zero in, the maximum output for each amplifier
would be limited to 140v, for a maximum of 280V output swing total. Thus the operating point
of the output stage should be optimized for different types of input signals. This operation is
performed by U3 with inputs from U6, U7 and U9. For Bipolar input signals U3 output is zero volts,
making U4 quiescent output zero volts. This sets the output amplifiers at zero volts out for zero
volts in (video in). For Unipolar Positive input signals, U3 output is approximately +2V, making U4
quiescent output -2V. This forces U2 to go to -125V, U1 to +125V, for the zero input volts. Now
the amplifiers are able to swing from -125 to +125 and from +125 to -125 respectively, in
response to a zero to +2V video input signal. For Unipolar Negative inputs, U3 output is -2v,
making all the amplifiers “flip” to the opposite operating extreme. U3 operates as a buffer with
U7 selecting the appropriate input reference voltage from U6 and U9.
Bias voltage for positioning the modulators quiescent operating point obtained from the
differential amplifier Q1, Q2, Q4 and Q5. This amplifier is capable of +/-550V, bias voltage at the
driver output terminals.

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
6
User Operation
In order to minimize the static DC operating potential across the E.O. cell, the bias voltage as
noted n the front panel of the power supply should be adjusted as follows:
1. When operating in the Unipolar Positive Mode, the bias should be adjusted in a positive
direction to reduce the static offset introduced by the drive electronics when operating in this
mode.
2. When operating in the Unipolar Negative Mode, the bias should be adjusted in a negative
direction to reduce the static offset
3. When operating in the Bipolar Mode, either direction is acceptable as the static offset of the
driver is zero volts.

ConOptics, Inc. 19 Eagle Road, Danbury, CT 06810 Phone [phone] Fax [phone]
Email: [email protected]om, or visit www.conoptics.com
7
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1 1Thursday, June 25, 2009
Size Document Number Rev
Date: Sheet of
CONOPTICS INC. DANBURY, CT. 06810
302A INSTALLATION DWG.
302A POWER SUPPLY
302A DRIVE ELECTRONICS
E.O. MODULATOR
J1m J2m
J3
VIDEO INPUT
SIGNAL SOURCE
J2J1
LASER
J8
VIDEO INPUT-50 OHM INPUT Z 2 VP-P MAX
INPUT MODE SELECT SWITCH
DRIVER WILL ACCEPT UNIPOLAR POSITIVE, UNIPOLAR NEGATIVE
OR BIPOLAR INPUT FORMAT. SEE MODE SELECT SW.
UNIPOLAR NEGATIVE: INPUT SIGNAL TO DRIVER IS NEGATIVE GOING, 0 TO -2V MAX
UNIPOLAR POSITIVE: INPUT SIGNAL TO DRIVER IS POSITIVE GOING, 0 TO +2V MAX
BIPOLAR: INPUT SIGNAL TO DRIVER GOES BOTH POS. AND NEG. ABOUT OVDC
+/- 1 VP-P MAX
REAR PANEL
EXTERNAL BIAS CONTROL INPUT
IF PROVIDED, CONTROLS DC BIAS WITH +/-
10V ANALOG INPUT