Model 5100 Displacement Follower Non-Contact Single Axis Tracking System Diversified Optronix Corp. 116 Quirk Road Milford, CT 06460 www.divop.
Table of Contents Introduction, 1 Equipment Supplied, 1 Warnings, 1 System Assembly, 2 Theory of Operation, 3 The Lenses, 5 Lens Systems, 5 Lens Calculations, 5 Precision of the Lens Calculations, 7 Targeting, 9 Target Requirements, 9 Target Illumination, 9 Techniques of Targeting, 10 Tracking Prerequisites, 11 Focusing and System Noise, 12 High-Voltage Adjustments, 12 Equipment and Functions, 13 Front Panel Functions, 13 Model 806 Optical Head, 15 Tracking Axis Alignment, 15 Rear Panel, 15 Operating Pr
Introduction The 5100 Displacement Follower is a non-contact, real-time motion measurement instrument that solves measurement problems where other instruments fail. It can measure the displacement of remote or inaccessible objects. The camera tracks the motion of the target and provides an analog output proportional to displacement. Custom optics allow a range in the field of view from 0.05” up to several feet.
System Assembly 1 Inspect the equipment for damage that might have occurred during shipment. If you find any damage, notify the shipping company immediately. 2 Attach the interconnecting cable from the control unit to the optical head and secure with the lock ring. 3 Attach the lens systems to the optical head. The lens screws into the extension barrel, and the extension barrel screws into the head. The thread system in the head is a standard Leica, 39mm diameter.
Theory of Operation The system is a non-contacting electro-optical displacement follower designed to track the motion of a target along any axis. The moving target under study must show a sharp discontinuity in the intensity of its reflected or emitted light. The tracker is, in fact, locking onto that light/dark interface. The lens system focuses the image of the discontinuity onto the photo cathode of an image dissector tube. A simplified drawing of this tube is shown in Figure 1.
There are two possible target configurations for measuring target displacement along the vertical axis: light over dark and dark over light. That means it must be possible to alter the phase of the current going through the deflection coils to deflect the electron image back to its original locked-on position and not away from this center position. In the 5000 Series, the target switch on the front panel of the control unit changes the phase. See Figure 2.
The Lenses Lens Systems To accommodate the working distances and measurement ranges that individual applications may require, the standard lens set supplied is appropriate for a variety of situations. Included in the set are a 105mm enlarging lens, a 50mm variable-focus camera lens, and five different extension tubes.
Figure 4 WD = Working Distance, MR = Full scale Measurement Range, fl = Focal Length of Simple Lens, EX = Length of Extension Tube needed, D = Distance from lens to Photo Cathode, A = Magnification (usually < 1) To calculate the size of the extension tube needed: 1 Estimate the expected full-scale displacement for the target under study 2 Calculate the magnification A = 0.15 in MR in or A = 3.
Example The lens to be used in this example is the 105mm enlarging lens supplied with the system. 1 Assume that the object under study is expected to exhibit a peak-to-peak displacement of one inch. 2 Calculate the magnification: A = 0.15 in. = MR in 3 0.15 in = 0.15 1 in Calculate the working distance, WD = (1 + 1/A) fl = (1 + 1/0.15) X 105 mm = 805 mm If you prefer to have the working distance in inches, multiply by 0.03937 to obtain 31.69 inches.
Figure 5 shows that the equivalent 105mm lens cannot be considered to be located exactly at the end of the extension tube. Its equivalent position is, in fact, approximately 13mm further along the optical axis than the position used in the calculations. This positioning of the lens in its diaphragm varies with different manufacturers and no one rule will solve the problem.
Targeting Target Requirements The 5000 Series operates by locking onto a sharp discontinuity in the intensity of an object’s reflected or emitted light. The target is actually the edge that can be seen at the light-dark interface and can be made up of any combination of reflected, absorbed, or emitted light. The contrast in light intensities should be at least three to one. The greater the contrast, the easier it is to obtain lock-on and the less system output noise is produced.
using a small screwdriver. For high light conditions, the high voltage may be reduced, or neutral density filters can be placed in front of the lenses. Note The light source must be DC or the tracker will detect the 60 Hz change in light intensity. Techniques of Targeting There are many ways of illuminating and setting up targets. This section will deal with the two most common: front lighting and back lighting.
Figure 11 Tracking Prerequisites Single Axis, Vertical or Horizontal The target and its motion should be located in the plane that is perpendicular to the optical axis. For successful lock-on, the target’s width must be greater than 10% of the full-scale measurement range, and its location must be along the tracking axis. Displacement Follower User’s Manual Version 1.
Figure 12 The minimum target required for vertical tracking along the vertical tracking axis. Focusing and System Noise Once you have selected a lens system selected and placed an illuminated target in front of the tracking head, open the lens aperture as wide as possible. Focus the target by moving either the head or the target to the proper position along the optical axis.
Equipment and Functions Front Panel Functions A 13 Level Meter LOCK 3 10 B 1 .3 30 100 .1 300 2 OPERATE .03 Diversified Optronix Single Axis Displacement Follower Controller Model 5100 3 LIGHT LEVEL CALIBRATE Time (msec) Acceleration 3 10 NORMAL LT SERVO 1 .3 30 100 POWER ON 1 12 Velocity .1 300 .03 11 100HZ 50KHZ 10KHZ ORTHO 4 Filter GAIN DISPLACEMENT VELOCITY ACCELERATION INPUT OUTPUT 5 6 7 8 9 10 Figure 13 1 Power Indicator Indicates that the system is on.
4 Output Filter Switch A three-position switch that selects a low pass R/C filter at the displacement outputs. For the best signal-to-noise ratio, select the lowest cutoff frequency possible without compromising operation. 5 Target Phase Switch Allows the system to track either a light-over-dark or a dark-over-light target as seen through the viewer. 6 Ortho Input External orthogonal input used to sweep the tracker along the axis perpendicular to both the tracking and optical axes.
Model 806 Optical Head The Model 806 Optical Head is the camera that senses the position of the target. The head contains an Electron Tubes Type 9670B image dissector tube on which the lens system images the target motion. This tube converts the light motion into electron motion. The head also contains a deflection yoke used to deflect the electron motion. A beam-splitting viewer is provided to focus the optical head on the target during all stages of operation. The lens system attaches to the head.
Operating Procedures General Operating Procedure 1 Prepare the target and lighting as specified. Note that the light source should be DC to eliminate the 120 Hz intensity modulation, and that the light intensity should be uniform over the target area to be measured. 2 Connect the optical head to the control unit with the cable supplied. 3 Connect the control unit to a 117 VAC power source. 4 Estimate the maximum displacement you expect from the target during operations.
13 Now, move the target or tracking head so that the circle is totally within the light area of the target. See Figure 15b. Adjust the lens aperture or light source for a reading of +20% on the front panel meter. If this reading cannot be achieved, then the high voltage to the photo tube may need to be adjusted. See Focusing and System Noise on page12). 14 Repeat steps 12 and 13 until the light and dark readings are in range. 15 Set the Light/Operate switch to Operate.
Velocity and Acceleration Measurement Operating Procedure Full-scale output for velocity and acceleration are determined as follows: 1 Note the full-scale range of measurement (FOV) of the lens being used. 2 With the system in operation, that is with the target in motion, set the Velocity Time Constant to 0.03ms and work down until you obtain velocity peaks of just under 10V P-P. Full-scale outputs are 10V P-P and the system will clip above that.
Worksheet For Parameter Measurement 1. System Field of View = FOV = inches 2. Accel. Due to gravity = 386.4 in. / sec 2 or = 9814 mm / sec millimeters 2 3. Set Velocity Time for Velocity output less than 10V P-P 4. Set Accel. time for Accel. output less than 10V P-P 5. Vel Full Scale = FOV = Vel Time (seconds) in / sec = 6. Target Vel 7. Vel Output = Sensitivity = Vel Output (peak) 5 Peak Vel Output Target Vel 8.
Calibration Resistors and capacitors have been selected to make the full-scale values on the time constant selector fall within ±5% of the value indicated. To calibrate the outputs further, it is necessary to move the target or sweep the tracker orthogonal to the plane of view and at a known velocity, making the output voltage proportional to the velocity or acceleration. The chart below shows some key frequencies for checking the velocity and acceleration outputs.
Common Problems Th most common errors are: 1 Improper target phase (L/D, D/L, etc.). 2 Improper centering of tracker on target. 3 Improper illumination of target: The light source must be DC. The light intensity must be calibrated for (-20 Dark) and (+20 Light). See Operating Procedures, page 16 . 4 Improper focusing of tracker on target. See Operating Procedures, page 16 . Displacement Follower User’s Manual Version 1.
System Calibration Calibration Procedure To calibrate the tracker, you need a digital voltmeter and a static calibrator that can accurately position a target. Since the output impedance of the system is approximately 50 ohms, the input impedance of any readout device should be at least 10,000 ohms. 1 Set up the tracker with the lens to be calibrated and focus on the static calibrator. The working distance should be the same as that used in practical application. See Figure 16.
Figure 18 6 Adjust the output gain to obtain a reading ±5 volts and record the gain setting. 7 For future reference, record the gain setting and the full-scale measurement range in the blank calibration Data Sheet is at the end of this manual. The full-scale measurement range equals twice the distance that the calibrator moved from Figure 17 to Figure 18 as read on the calibrator.
Standard Lens Set Components of the Standard Lens Set Quantity 1 1 1 1 1 1 1 Item 105mm Enlarging Lens 50mm Camera Lens 72mm Extension Tube 10mm Extension Tube 15mm Extension Tube 20mm Extension Tube 30mm Extension Tube These charts shows some of the optical parameters that can be obtained using combinations of the above components.
Lens Calibration Data Sheet LENS CALIBRATION DATA SHEET CUSTOMER: DATE: PO#: S/N: 1 2 3 4 5 4 5 LENS NUMBER: FOCAL LENGTH: EXTENSIONS: WORKING DISTANCE: RANGE OF MEASUREMENT: GAIN SETTINGS FOR PROPER CALIBRATION 1 2 3 H H V V DIVERSIFIED ENGINEERING 283 INDIAN RIVER ROAD • ORANGE, CT • (203) 799-7875 Displacement Follower User’s Manual Version 1.
Appendix Limited Warranty Diversified Optronix Corp. (DivOp) warrants that the Model 5100 will be free from defects in material and workmanship for a period of one (1) year from the date of purchase. DivOp will, at its discretion, repair or replace any part(s) found to be defective in the Model 5100 resulting from defective workmanship, material or both. All costs for packaging and transportation to Milford, CT, are the responsibility of the customer.
