waveguide:manuals:ls-15-3005
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waveguide:manuals:ls-15-3005 [2016/01/15 03:31] – [Operation] Michael Radunsky | waveguide:manuals:ls-15-3005 [2016/01/19 01:29] (current) – removed Michael Radunsky | ||
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- | ======LS-105 2-D EO Laser Scanner Driver and LS-15-3005 Scanner Prototype Manual====== | ||
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- | =====Introduction===== | ||
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- | Please read [[: | ||
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- | Please be aware that the beam steerer and driver are still in the prototype stage. | ||
- | If any glitches or malfunctions are noticed please contact Vescent Photonics. | ||
- | Please let us know if you have any suggestions for improving the functionality and/or capability of our scanner. | ||
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- | Vescent Photonics\\ | ||
- | 14998 W. 6th Ave, Suite 700\\ | ||
- | Golden, CO 80401\\ | ||
- | Tel: 303-296-6766\\ | ||
- | Fax: 303-296-6783 | ||
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- | ==General Warnings and Cautions== | ||
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- | The following general warnings and cautions are applicable to this instrument. | ||
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- | 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 operation and capabilities. | ||
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- | There are no serviceable parts inside the instrument. Work performed by persons not authorized by Vescent Photonics may void the warranty. | ||
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- | Although ESD protection is designed into the instrument, operation in a static-fee work area is recommended. | ||
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- | To avoid electrical shock hazard, connect the instrument to properly earth-grounded, | ||
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- | Do not clean outside surfaces of any Vescent Photonics products with solvents such as acetone. Front panels on electronics modules may be cleaned with a mild soap and water solution. Do not clean optics modules. | ||
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- | ==Limited Warranty== | ||
- | Vescent Photonics warrants this product to be free from defects in materials and workmanship for a period of one year from the date of shipment. If this product proves defective during the applicable warranty period, Vescent Photonics, at its option, either will repair the defective product without charge or will provide a replacement in exchange for the defective product. The customer must notify Vescent of the defective product within the warranty period and prior to product return. The customer will be responsible for packaging and shipping the defective product back to Vescent Photonics, with shipping charges prepaid. | ||
- | Vescent Photonics shall not be obligated to furnish service under this warranty from damage caused by service or repair attempts made without authorization by Vescent Photonics; from damage caused by operation of equipment outside of its specified range as stated in either the product specifications or operators manual; from damage due to improper connection to other equipment or power supplies. | ||
- | 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' | ||
- | Vescent Photonics | ||
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- | =====Operating Parameters===== | ||
- | Absolute Maximum Ratings | ||
- | Note: All modules designed to be operated in laboratory environment | ||
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- | | **Parameter** | **Rating** | | ||
- | |Environmental Temperature | >15°C and <30°C| | ||
- | |Environmental Humidity | <80% | | ||
- | |Environmental Dew Points | <20°C | | ||
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- | =====Terminology===== | ||
- | 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. | ||
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- | =====Specifications===== | ||
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- | | **Parameter** |**Value** | **Comment** | | ||
- | |Number of HV Outputs|3|Two for horizontal electrodes and one for vertical.| | ||
- | |Maximum HV|100 V< | ||
- | |Maximum short burst HV current |150 mA | For timescales <20 μs.| | ||
- | |Maximum DC HV current | 6 mA | | | ||
- | |HV Output Impedance | 1 kΩ | | | ||
- | |Clock Out Voltage | 3.3V | | | ||
- | |Vertical Analog Control Voltage Input | 0-10 VDC | Zero volts input is no deflection and 10 V is maximum deflection.| | ||
- | |Horizontal Analog Control Voltage Input | -10 V to +10 VDC | -10 V steers all the way to the left, 0 V is centered, and +10 V steers all the way to the right.| | ||
- | |Input Impedance for Analog Control Signals | 1 MΩ | | | ||
- | |Clock Input Acceptable Frequency Range | 500 Hz to 10 kHz | At frequencies above 10 kHz the device will not operate to specification.| | ||
- | |Clock Input Acceptable Voltage Range | 3.3 V | 3.3 V is ideal. | ||
- | |Internal Square Wave Frequency | 5 kHz | | | ||
- | |Required Thermister Resistance | 10 kΩ | | | ||
- | |Required TEC Resistance | ≥2 Ω | | | ||
- | |Maximum TEC Current | 200 mA | | | ||
- | |Power Input | 5V, 500 mA | | | ||
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- | =====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. | ||
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- | The cable plugs into the LS-105 with a push connector. | ||
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- | ===Prototype EO Scanner Optical Head=== | ||
- | The 1.5 µm LS-15-43005-FC/ | ||
- | 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. | ||
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- | =====Connections and Controls===== | ||
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- | 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. | ||
- | Please allow 1 to 2 minutes for the SEEOR to temperature stabilize. | ||
- | Now the beam steerer is ready for steering. | ||
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- | Front Panel Controls (from left to right) | ||
- | |Power Switch|This turns the unit on. Up is on and down is off.| | ||
- | |Power LED|This is on when the unit is on.| | ||
- | |Temperature LED|This LED turns green when the temperature is stabilized.| | ||
- | |Optical Head|High Voltage and temperature control output connector.| | ||
- | |Horizontal|User can input the external signal. Maximum voltage should not exceed ±10 V. Input impedance is 1 M Ω. This input will steer the beam horizontally.| | ||
- | |Vertical|User can input the external signal. Maximum voltage should be held within 0 to +10 V. Input impedance is 1 MΩ. This input will steer the beam vertically.| | ||
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- | Back panel Controls (from left to right) | ||
- | |Polarity Clock out|This outputs the clock frequency. | ||
- | |Polarity Clock in|If the user does not connect a clock input, the driver will use its internal clock that is set to 5 KHz. If the user inputs the clock signal, the internal clock will be disabled automatically and the external clock will be used.| | ||
- | |Power In|Power the driver with the AC adapter that is included with the package.|</ | ||
- | =====Advanced Settings===== | ||
- | 3.3. Background on Driving LC Devices | ||
- | 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, | ||
- | Common problems with square waves are illustrated on the left of Figure 9. 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 9, 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/s, which is beyond the capabilities of most amplifiers when driving a capacitive load. The right hand side of Figure 9 shows an ideal square wave and its associated constant E-field magnitude. Figure 10 plots an example waveform from an LS-105. | ||
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- | Figure 9: Left) Drawing of a typical square wave as provided by common amplifiers. Slew rate, DC offset, overshoot, and ripple all result in a non-constant E-field magnitude. Since it is the E-field magnitude that the LC responds to this can be problematic. Right) Drawing of an ideal square wave and its related constant E-field magnitude. The goal of a proper LC-driver is to get as close to this ideal as possible. | ||
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- | Figure 10: Plot of a typical high voltage output from the LS-105. | ||
- | 3.4. SEEOR: An Asymmetric LC Device | ||
- | For conventional LC devices such as displays, the electronics are constructed to keep the DC offset minimized over all operational square wave voltages. | ||
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- | Figure 11: The two types of DC offsets that are important for proper control of the SEEOR. | ||
- | 3.5. Internal Factory-Set Trim Pots | ||
- | There are a number of internal trim pots that are factory set. These are typically set for a specific scanner. | ||
- | By unscrewing the four hex-bolts and the two BNC washers, the front panel may be folded up to allow access to four of the internal trim pots, as shown in Figure 12. From here, the user may adjust the magnitude and sign of the voltage dependent offsets. If the scanner has more than acceptable twinning or splitting of the scanned beam, especially at maximum deflection, then it may be beneficial to adjust the magnitude of the voltage dependent offset. | ||
- | Also shown in Figure 12 are the trim pots for setting the Freedericksz voltages. | ||
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- | Figure 12: Trim pots that are accessible after removing the front panel. | ||
- | There is another set of trim pots that are only accessible by sliding the electronics out of the housing. | ||
- | Inside the LS-105 there are two electronics boards. | ||
- | There is also a trim plot to minimize the constant DC offset for each of the three SEEOR electrodes, as shown in Figure 13. One of these is underneath the temperature control board. | ||
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- | Figure 13: Trim pots that are only accessible by sliding the electronics out of the housing. | ||
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waveguide/manuals/ls-15-3005.1452828718.txt.gz · Last modified: 2021/08/26 14:26 (external edit)