waveguide:manual
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waveguide:manual [2016/01/28 00:06] – [Connections and Controls] Michael Radunsky | waveguide:manual [2021/08/26 15:26] (current) – external edit 127.0.0.1 | ||
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This warranty is in lieu of all other warranties including any implied warranty concerning the suitability or fitness of the product for a particular use. Vescent Photonics shall only be liable for the cost of repairs or replacement of the defective product within the warranty period. Vescent Photonics shall not be liable for any damages to persons or property resulting from the use of the product or caused by the defect or failure of this product. Vescent Photonics' | This warranty is in lieu of all other warranties including any implied warranty concerning the suitability or fitness of the product for a particular use. Vescent Photonics shall only be liable for the cost of repairs or replacement of the defective product within the warranty period. Vescent Photonics shall not be liable for any damages to persons or property resulting from the use of the product or caused by the defect or failure of this product. Vescent Photonics' | ||
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=====Operating Parameters===== | =====Operating Parameters===== | ||
Absolute Maximum Ratings | Absolute Maximum Ratings | ||
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=====Terminology===== | =====Terminology===== | ||
- | The LS-105 is a miniature electronics module designed to control an LC-waveguide electro-optic laser scanner. | + | The LS-105 is a miniature electronics module designed to control an LC-waveguide electro-optic laser scanner. |
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With the LS-105 the amplitude of the square wave for each electrode is controllably adjustable from a minimum value, herein referred to as the Freedericksz voltage, to a maximum value of approximately 100Vrms. This is controlled via two analog input voltages via front panel BNC connectors, one for horizontal and one for vertical. | With the LS-105 the amplitude of the square wave for each electrode is controllably adjustable from a minimum value, herein referred to as the Freedericksz voltage, to a maximum value of approximately 100Vrms. This is controlled via two analog input voltages via front panel BNC connectors, one for horizontal and one for vertical. | ||
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=====Operation===== | =====Operation===== | ||
- | The LS-105 is shipped with a 5 V power supply and a cable for connection to the SEEOR, as shown in Figure 2. If you purchased a chip level SEEOR the cable will have a connector on one end and clip-connectors on the other end. If you purchased a fiber-coupled SEEOR the cable will be connectorized at both ends. | + | The LS-105 is shipped with a 5 V power supply and a cable for connection to the SEEOR, as shown in <imgref shipkit>. If you purchased a chip level SEEOR the cable will have a connector on one end and clip-connectors on the other end. If you purchased a fiber-coupled SEEOR the cable will be connectorized at both ends. |
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- | The cable plugs into the LS-105 with a push connector. | + | The cable plugs into the LS-105 with a push connector |
===Prototype EO Scanner Optical Head=== | ===Prototype EO Scanner Optical Head=== | ||
- | The 1.5 µm LS-15-43005-FC/PC is a prototype 2D electro-optical beam steerer. | + | The 1.5 µm LS-15-3005-FC/PC is a prototype 2D electro-optical beam steerer. |
- | The scanner is packaged with a PM fiber pigtail (see Figure 4) with an FC/PC connector. This is an engineering package and not intended for field use. Its input must be linearly polarized light with the polarization axis parallel to the FC key. | + | |
=====Connections and Controls===== | =====Connections and Controls===== | ||
<color red> | <color red> | ||
The user should NEVER disconnect the control cable from the scanner or driver while power is applied ("hot swapping" | The user should NEVER disconnect the control cable from the scanner or driver while power is applied ("hot swapping" | ||
- | With the power switch in the OFF or down position (see Figure 5) connect the power supply to the wall plug and to the LS-105 back panel (see Figure 6). Use the provided cable to connect the LS-105 driver to the SEEOR unit. The unit is now ready to be powered on. The driver provides up to 110 V to the beam steerer. | + | With the power switch in the OFF or down position (see <imgref front>) connect the power supply to the wall plug and to the LS-105 back panel (see <imgref rear>). Use the provided cable to connect the LS-105 driver to the SEEOR unit. The unit is now ready to be powered on. The driver provides up to 110 V to the beam steerer. |
Please allow 1 to 2 minutes for the SEEOR to temperature stabilize. | Please allow 1 to 2 minutes for the SEEOR to temperature stabilize. | ||
Now the beam steerer is ready for steering. | Now the beam steerer is ready for steering. | ||
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Front Panel Controls (from left to right) | Front Panel Controls (from left to right) | ||
|Power Switch|This turns the unit on. Up is on and down is off.| | |Power Switch|This turns the unit on. Up is on and down is off.| | ||
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Back panel Controls (from left to right) | Back panel Controls (from left to right) | ||
|Polarity Clock Out|This outputs the clock frequency. | |Polarity Clock Out|This outputs the clock frequency. | ||
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|Power In|Power the driver with the AC adapter that is included with the package.| | |Power In|Power the driver with the AC adapter that is included with the package.| | ||
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- | A typical angle tuning curve for a SEEOR is shown in the figure. | + | A typical angle tuning curve for a SEEOR is shown in the figure. And typical output beam quality is shown next to it. |
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=====Advanced Settings===== | =====Advanced Settings===== | ||
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When designing LC-drive electronics there are two important inherent properties. First, for a typical nematic LC, the EO response is via an induced dipole interaction. This means that the LC-molecules respond to the magnitude of the applied electric field but not the sign. Second, it is necessary that the time-averaged voltage across an LC optic is “DC-balanced” to have zero or minimal offset. This can be critical for both the operation and lifetime of the device. Prolonged time-averaged DC offsets will drive ion-migration inside the LC material, which can be deleterious for both the short-term performance and ultimately the lifetime of the device. On short timescales ion-migration will create a shielding field to cancel the applied voltage, which will cause the LC molecules to “relax” or “sag.” Precision applications can be sensitive to this sag even during short timescales. On long timescales ion-migration can result in the build up of permanent charge layers within the LC, thereby causing a “burn-in” which may forever degrade the operation of the device. The LC-drive electronics must account for both the “induced dipole” response and the “DC-balance” constraint.\\ | When designing LC-drive electronics there are two important inherent properties. First, for a typical nematic LC, the EO response is via an induced dipole interaction. This means that the LC-molecules respond to the magnitude of the applied electric field but not the sign. Second, it is necessary that the time-averaged voltage across an LC optic is “DC-balanced” to have zero or minimal offset. This can be critical for both the operation and lifetime of the device. Prolonged time-averaged DC offsets will drive ion-migration inside the LC material, which can be deleterious for both the short-term performance and ultimately the lifetime of the device. On short timescales ion-migration will create a shielding field to cancel the applied voltage, which will cause the LC molecules to “relax” or “sag.” Precision applications can be sensitive to this sag even during short timescales. On long timescales ion-migration can result in the build up of permanent charge layers within the LC, thereby causing a “burn-in” which may forever degrade the operation of the device. The LC-drive electronics must account for both the “induced dipole” response and the “DC-balance” constraint.\\ | ||
An optimum voltage waveform that satisfies both of these LC requirements is a high quality square wave with no DC offset. Since the LC material only responds to the magnitude of the electric field and not the sign, by rapidly switching the voltage polarity the LC material will see the same E-field magnitude and simultaneously the need for DC balance will be satisfied. While in principle the square wave provides the ideal waveform, for anyone who has ever worked with square waves they will know that a high quality square wave is easier said than done. This is especially true when driving capacitive loads such as LC cells. Furthermore, | An optimum voltage waveform that satisfies both of these LC requirements is a high quality square wave with no DC offset. Since the LC material only responds to the magnitude of the electric field and not the sign, by rapidly switching the voltage polarity the LC material will see the same E-field magnitude and simultaneously the need for DC balance will be satisfied. While in principle the square wave provides the ideal waveform, for anyone who has ever worked with square waves they will know that a high quality square wave is easier said than done. This is especially true when driving capacitive loads such as LC cells. Furthermore, | ||
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- | Common problems with square waves are illustrated on the left of Figure 7. Typically, the square wave is generated via amplification of a low voltage clock from a function generator or other clock source. Frequently, amplifiers are susceptible to several common problems: offsets (often frequency dependent which hampers trimming), limited slew rates, limited settling times (can cause overshoot and ringing), and limited current output. As shown on the left of Figure 7, all of these problems can have dramatic impacts on the magnitude of the electric field, i.e. what the LC responds to. For high-speed LC devices, the slew rate required to minimize any transient LC response during the polarity switch can be >100 Volts/ms, which is beyond the capabilities of most amplifiers when driving a capacitive load. The right hand side of Figure 7 shows an ideal square wave and its associated constant E-field magnitude. | + | Common problems with square waves are illustrated on the left of <imgref waveform> |
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waveguide/manual.txt · Last modified: 2021/08/26 15:26 by 127.0.0.1