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IEEE SENSORS JOURNAL, VOL. 12, NO. 6, JUNE 2012
Design, Qualification, Calibration and Alignment of Position Sensing Detector for the NuSTAR Space Mission Carl Christian Liebe, Bruce W. Bauman, Gerald R. Clark, Rick Cook, Branislav Kecman, Kristin Kruse Madsen, Peter Mao, Patrick Meras, Jr., Hiromasa Miyasaka, Mark Cooper, Christopher Scholz, and Jack Sedaka
Abstract— A commercial position sensing detector (PSD) has been used to measure mast deflections on a space based X-ray telescope (NuSTAR). This paper describes the space qualification process for utilizing a commercial PSD sensor in space. This discussion includes packaging, environmental testing, selection of flight candidate devices, calibration and alignment.
Laser
Index Terms— Metrology system, NuSTAR, position sensing detector, space qualification.
Optics bench
PSD
10 meter deployable mast Detector bench
Fig. 1. Sketch of the NuSTAR metrology system layout. The lateral laser beam motion is ∼1 mm.
I. I NTRODUCTION
T
HE NuSTAR is a NASA Small Explorer (SMEX) mission scheduled to launch into low-Earth equatorial orbit in 2012. The NuSTAR space mission will deploy two identical high energy X-ray telescopes that will assist in advancing the scientific understanding of black holes, map supernova explosions, and active galaxies [1]. The mission’s telescopes consist of specially coated X-ray optics and newly developed X-ray detectors which require a focusing length of ∼10 meters. To achieve the required focal length, the NuSTAR payload extends a deployable mast which separates the X-ray optics from the X-ray detectors by ∼10 meters in orbit. The mast introduces small thermal distortions that will smear the Xray images, because the X-ray detectors will shift their lateral position relative to the X-ray optics. A metrology system is
Manuscript received September 6, 2011; revised November 29, 2011; accepted December 8, 2011. Date of publication January 2, 2012; date of current version April 25, 2012. This work was supported in part by the Jet Propulsion Laboratory, California Institute of Technology, Space Radiation Laboratory, California Institute of Technology, Space Sciences Laboratory, U.C. Berkeley, and Pacific Silicon Sensor, Inc., and was sponsored by the National Aeronautics and Space Administration. The associate editor coordinating the review of this paper and approving it for publication was Prof. Julian C. C. Chan. C. C. Liebe, G. R. Clark, P. Meras, Jr. M. Cooper, and J. Sedaka are with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099 USA (e-mail:
[email protected]; gerald.j.clark@jpl. nasa.gov;
[email protected];
[email protected];
[email protected]). R. Cook, B. Kecman, K. K. Madsen, P. Mao, and H. Miyasaka are with the Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 USA (e-mail:
[email protected];
[email protected];
[email protected];
[email protected];
[email protected]). B. W. Bauman is with Pacific Silicon Sensor, Inc., Westlake Village, CA 91362 USA (e-mail:
[email protected]). C. Scholz is with the University of California, Berkeley, Space Sciences Lab, University of California, Berkeley, Berkeley, CA 94720-7450 USA (e-mail:
[email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JSEN.2011.2181355
included to measure the lateral mast motion. The metrology system consists of two laser pointers mounted on the optics side of the telescope and two PSDs mounted on the detector side of the telescope [2]-[4]. This is sketched in Figure 1. An alternative approach for measuring structural deformation is to utilize a visible camera tracking small illuminated targets on the structure [5]-[6]. However, qualifying a camera for space applications is more costly and complicated than qualifying a laser [7] and a PSD. Tracking targets mounted on a large structure for measuring structural deformation is a rapidly growing field. For ground based applications (e.g. a large telescope/antenna) typically a laser tracker (a surveyor’s instrument) is used [8] or a custom target tracking system is built [9]. For aircraft applications, target tracking can be used for autonomous aerial refueling [10] and for measuring airplane fuselage flexing for Synthetic Aperture Radar (SAR) [11]. Space applications include formation flying [12], rendezvous and docking [12] and flexible structure deformation measurement [5]-[6]. The novelty of this paper is to describe how a commercial PSD sensor can be qualified and used in a space environment. The use of a commercial PSD sensor is a very cost effective way to implement this type of measurement. This paper is relevant to future space instruments that rely on large, lightweight, flexible structures, formation flying or rendevouz and docking. The first section discusses PSD technology, design and manufacturing. The next section covers the flight qualification that was performed on the PSDs, which included testing and characterization of the dark current over an extended period of time. Also described is the calibration procedure of the PSD chip. Finally, the alignment of the photo sensitive area of the PSD will be discussed. The PSD chip specifications are shown in Table I.
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LIEBE et al.: DESIGN, QUALIFICATION, CALIBRATION AND ALIGNMENT OF PSD FOR THE NuSTAR SPACE MISSION
TABLE I PSD S PECIFICATIONS
Bias Voltage
Simulation of the PSD chip reflection
Measured Value 20 mm × 20 mm ∼ 40 nA Two dimensional 80 µm over central 14 mm of chip Measured to ∼100 ppm/C including electronics amplifier temperature sensitivity 30 Volts
y1
x2
x1
y2 Fig. 2.
PSD terminal locations and current readouts.
II. PSD C HIP D ESIGN A two-dimensional PSD is a large photodiode. It can measure the centroid position of a light spot falling on its surface in two dimensions with respect to itself. The PSD has four terminals; two are on the back side of the photodiode and two are on the front side, with those on the back oriented perpendicularly to those on the front as shown in Figure 2. The photoelectric current generated by the incident laser spot flows through the device and generates two output currents, X1M and X2M , and two input currents, Y1M and Y2M . Based on the currents, it is possible to calculate the light centroid position utilizing the equations below: PSDDimension (X 1 − X 2 ) 2(X 1 − X 2 ) PSDDimension (Y1 − Y2 ) = 2(Y1 − Y2 )
X Measured = YMeasured
(1)
where X1 , X2 , Y1 and Y2 are currents flowing to/from the PSD. It is observed that the intensity of the incident light spot does not affect the calculation of the laser centroid. This means that potential decrease of the light spot intensity will not require a new calibration of the PSD during flight. There is an additional background signal from sources such as sun stray light in the baffles, dark current in the PSD, the Moon or Earth in the Field of View (FOV) etc. Therefore the laser is turned off 4 times a second and the background signals: X1B , X2B , Y1B and Y2B are measured. The values X1 , X2 , Y1 and Y2 used in the above equation are therefore not the measured values, but the measured value minus the background currents. X1 = X1M − X1B etc. The PSD selected for the NuSTAR metrology system was a DL400-7 PSD chip mounted on a custom metalized ceramic with leads added, manufactured by Pacific Silicon Sensor, Inc. The “DL” identifies the chip as a “Duo-Lateral” PSD; the “−7” identifies the type of silicon and the wafer fabrication process used to make this chip. The DL400-7 chip has a light
Reflection (%)
Parameters PSD size Dark current (at room temperature) Type Deviation from linear positional response Change in optical response over temperature
2007
60 50 40 30 20 10 0 200
400
Fig. 3.
600 800 Wavelength (nm)
1000
Simulation of the PSD chip reflection.
responsive region, known as the “active area”, of 20 mm × 20 mm. The chip is manufactured on high purity, high resistivity N type float zone silicon with resistivity in the range of 4000-8000 ohm-cm. To create the light responsive active area, a P-N junction is formed in the N type silicon by doping P type impurities into the N type silicon. Ion implanting is used to accomplish this doping, implanting P+ ions into the topside of the N type silicon to form the active area region and implanting N+ ions into the backside region to form a N+ layer. Both P+ and N+ doping concentrations and junction depths are done in a very precise manner to maximum spectral responsivity and to form very uniformly doped layers across the entire 20 mm × 20 mm light response region to maximize positional linearity. An oxidation layer is added over the topside chip surface to provide passivation. This passivation layer also serves as an optical anti-reflective coating, grown to a specific thickness to enhance light transmission for a specific wavelength range. A simulation of the reflection is shown in Figure 3. To complete the chip, metalized contact bars are added on opposing ends of the active area on the topside and bottomside of the chip, providing anode and cathode connections, as described above. The PSD chip was mounted on a custom metalized alumina ceramic substrate, to which flat leads were attached, suitable for forming into J leads. Although a typical commercial PSD package has only four connections, X1 , X2 , Y1 , Y2 , the need for high reliability necessitated designing a carrier with multiple redundant connections for each of the four outputs. Additional non-functioning leads were also added to provide enhanced package attachment strength to withstand the rigors of space launch. The PSD chip backside cathode connections were attached to the metalized ceramic with space qualified silver conductive epoxy. The PSD chip anode connections were made to the substrate with gold wire bonds. Flat leads were soldered to the substrate and later formed into J leads for mounting onto the PSD signal processing PCB. An alumina frame was epoxy attached on the substrate perimeter to provide a mounting surface for a temporary protective window. The PSD chip is operated without a window or cover. This necessitated storing the PSD chips in constant dry nitrogen atmosphere until launch. In Figure 4 is shown a picture of the packaged PSD chip. III. F LIGHT Q UALIFICATION A total of 20 custom packaged PSD detectors were procured. All PSD chips were screened to the criteria shown in Table II.
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1000.0 Leakage current versus temperature
Leakage current [nA]
100.0
10.0
1.0
0.1 20 Fig. 4.
0
20
40
Picture of the PSD assembly. Fig. 5. Dark current versus temperature (°C) for a representative PSD chip. TABLE II
Inspection/Test High Temperature Bake Temperature Cycling Constant Acceleration Initial Electrical Performance Test Burn-In Final Electrical Test
External Visual
Condition T = +60 C, 24 hours in vacuum 20 Cycles, −45 °C to +60 °C 6000G in Z axis
160 Hours at 70 °C Repeat initial electrical performance test. PDA of 5% shall apply. 10 ×
TABLE III T ESTS P ERFORMED ON D EVICES C OMPLETING S CREENING (B UT N OT U SED FOR F LIGHT ) Test Physical Dimensions Solderability Bond Strength Die Attach Integrity DPA procedures for diodes (Destructive Physical Analysis)
MIL-STD-750 METHOD 2066 2026 2037 2017 2101
Sample Size 3 6 wires 3 devices 2 devices
Also, a number of chips were subjected to the destructive tests shown in Table III. For space applications, a silicon detector will usually be radiation tested as part of the qualification program. The dark current is expected to increase with total dose. However, in this specific case, there were 3 factors that determined that radiation testing would not be performed: 1) The radiation environment is benign: the total ionizing dose is expected to be ∼2 kRads(Si) and the displacement damage ∼5·107 MeV/g(Si). 2) Typically silicon detectors are used to detect faint signals from e.g. stars. and the dark current must be kept to a
Temperature
S CREENING S PECIFICATIONS FOR THE PSD C HIPS
~40C, 2−3 weeks
~20C, 2 days
~20C, 2 days ~−28C, 2 days Time
Fig. 6. Temperature profile used for the long duration test for the PSD selection.
minimum. In this application, the PSD is detecting a very bright laser signal. The laser signal is ∼60 µA and the dark current is ∼40 nA. The A/D converters are set to not saturate, if the dark current is of equal intensity to the signal. In other words, the dark current can increase a factor of 1500 and the system will still operate within requirements. 3) The dark current is subtracted 4 times a second as described in the last section. As long as the dark current does not saturate the signal chain, it is acceptable. IV. PSD C HIP S ELECTION To select the flight PSDs, all chips were subjected to temperature extremes and bias voltage for a month, with continuous monitoring of the dark current. This qualification process was developed at Caltech for Silicon detectors flown on several cosmic-ray missions (Voyager, ACE and STEREO). The PSD chips with the lowest and most stable dark currents were selected as flight candidates. The dark current is shown in Figure 5 for a representative PSD chip. The temperature profile is shown in Figure 6. The measured dark currents for 7 different chips are shown in Figure 7. In Figure 7, it is observed that one PSD chip does increase its dark current over the period from day 1 to day 15. This specific PSD chip was disqualified. The other 6 PSD chips were accepted as flight candidate chips. PSD chips with lower dark current are more desirable than PSD chips with higher dark current.
LIEBE et al.: DESIGN, QUALIFICATION, CALIBRATION AND ALIGNMENT OF PSD FOR THE NuSTAR SPACE MISSION
Caltech PSD T/V RUN
Leakage current [nA]
1000
100
10
1
0
2009
the translation stages and the PSD chip is unknown (XOffset ,YOffset ). The scaling factors of x and y are unknown (Xscalefactor ,Yscalefactor ) and finally the angles between the PSD chip sides and the translation stages are unknown (XAngle,YAngle ). X Model = (X TranslationStage − X offset ) × X Scalefactor + X Angle ×(YTranslationStage − Yoffset ) × YScalefactor
SN 26 SN 17 SN 28 SN 35 SN 22 SN 29 SN 39
Fig. 7. Dark current for seven PSD chips over a period of 25 days. It is observed that one PSD chip (S/N:35) did not have a stable dark current over the 14 days of hot soak. Therefore, this PSD was disqualified for flight. The other PSD chips were acceptable for flight.
V. PSD C ALIBRATION A PSD chip has some light response non-linearity. Also, the laser spot that illuminates the PSD chip is not infinitely small (size ∼2 mm). Therefore, when the laser beam approaches the edge of the PSD detector, a part of the laser beam is not intercepted by the photosensitive area of the PSD. This means the laser centroid is shifted towards the center of the PSD chip and the individual PSD chips have to be calibrated with a specific metrology laser as the laser spot shape strongly influences the PSD response close to the edges. The calibration of the PSD chip was done by placing the metrology detector on a rigid aluminum structure with 2 accurate orthogonal translation stages (the translation stages were accurate to ∼5 microns, but subsequent data analysis showed that the two translation stages were only mounted orthogonally to within 0.5°-1.0°) The laser is placed on another rigid aluminum structure ∼10 meters from the detector and the laser beam is pointed approximately at the center of the PSD chip. The metrology detector is then moved in a rectangular grid by the translation stages. The detected position of the laser beam is recorded on a grid with 0.25 mm spacing. For every 100 measurements, the translation stages are moved back to the home position, to compensate for drift in the set-up or the building itself. Since the laser beam has to travel a horizontal distance of ∼10 meters in atmospheric air, it will be subjected to air turbulence. A test was conducted to assess the air turbulence. A stationary laser spot was recorded with a sampling frequency of 1 KHz at a distance of 10 meters. When the laser spot position was averaged over a period of 1 second, the laser spot centroid noise was less than 7 microns due to atmospheric turbulence. Therefore, each data point is averaged over 1 second for the calibration. This error can be ignored compared to the overall calibration residual. Figure 8 shows a picture of the measured laser beam positions recorded on a grid with a spacing of 250 microns. In Figure 8, the red dots are the measured positions (XMeasured /PSDDimension,YMeasured /PSDDimension ) (1). The blue dots are the model (XModel ,YModel ). The actual grid that the translation stages traversed is known with high accuracy (XTranslationStage,YTranslationStage). The offset between
YModel = (YTranslationStage − Yoffset ) × YScalefactor + YAngle ×(X TranslationStage − X offset ) × X Scalefactor
(2)
At this point, there are ∼6000 equations (measurement points) and 6 unknowns (Xoffset , Xscalefactor , Xangle , Yoffset , Yscalefactor , Yangle ). We want to minimize the following expression: 2 2 X Measured YMeasured − X Model + −YModel PSDDimension PSDDimension Allpoints
(3) This can be done in Excel Solver or Matlab fminsearch or similar. The resulting grid is shown as blue dots in Figure 8. Xoffset and Yoffset represents an arbitrary setting of the translation stages. Xscalefactor and Yscalefactor would be 0.1 in an ideal world. However, due to the actual PSD chip characteristics and component tolerances in the amplifier they vary an amount. Xangle and Yangle represent how the sides of the PSD chip were aligned to the translation stages. No special effort was made to align them accurately. The distance between the measured value and the model values represents how linear the PSD chip response is. When the chip was calibrated over the central 14 mm of the chip, the maximum deviation (from a linear response) was 80 microns. In Figure 9 and 10 are shown the x and y corrections (XCorrection ,YCorrection ) based on interpolation of Figure 8. The measurements used for the interpolation are: X Correction = X Model − X Measured /PSDDimension YCorrection = YModel − YMeasured /PSDDimension
(4)
The interpolated correction functions based on the above measurements are called CORX(XMeasured ,YMeasured ) and CORY(XMeasured ,YMeasured ). An experiment was also conducted to measure the thermal expansion of the PSD chip. A calibration (as described above) was done at room temperature ∼18.5 °C. It was found that the average Xscalefactor was 0.099256 and the average Yscalefactor was 0.098708. The PSD chip and amplifier circuitry were then heated up to 23.5 °C and the exact same experiment was repeated. At this point, the Xscalefactor was 0.099327 and Yscalefactor was 0.098687. These relative changes over ∼5 °C temperature range correspond to a thermal expansion of 144 ppm/°C in the x-axis and 81ppm/ °C in the y- axis. Only one set of temperature measurements were done. This is not enough to estimate the statistical uncertainly of this measurement accurately. However, based on the available data it is estimated that the uncertainty is ∼50 ppm/°C. When the PSD chip is removed from the calibration setup, the absolute calibration information is lost. However, the
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1 0.8 0.6 0.4 0.2 0 −0.2 −0.4 −0.6 −0.8 −1 −1 −0.8 −0.6 −0.4 −0.2
0
0.2
0.4
0.6
0.8
1
Fig. 8. Result of PSD chip calibration. The PSD chip is calibrated over an area of +/− 9.5 mm. The red dots are the actual measured positions of the laser beam (XMeasured /PSDDimension ,YMeasured /PSDDimension ). The blue dots are a model that is fitted to the measured data (XModel ,YModel ).
0.03 0.02 0.02 0.01 0 0 −0.01
−0.02
−0.02 −0.04 Fig. 9. Correction function [CORX(XMeasured ,YMeasured )] for the x-coordinate of the PSD reading. The picture covers an area of −10 mm to +10 mm in both axes. Temperature scale indicates correction values.
relative calibration information is still valid. As an example, a laser impinges the PSD chip on a specific location and is measured. Subsequently, the PSD chip measures the laser spot at a different position. Utilizing the calibration, it is possible to calculate the exact change in laser spot position. On the NuSTAR project, the absolute calibration information will not be established before the observatory is deployed on orbit. At
Fig. 10. Correction function [CORY(XMeasured ,YMeasured )] for the y-coordinate of the PSD reading. The picture covers an area of −10 mm to +10 mm in both axes. Temperature scale indicates correction values.
that point, the X-ray telescope will observe a bright X-ray source with known celestial coordinates. From that point on, all observations are done relative to the laser position during this observation. For more details see [3]. A measurement point acquired during orbit (XOrbit ,YOrbit ) is calculated the same way as (XMeasured ,YMeasured ) shown in
LIEBE et al.: DESIGN, QUALIFICATION, CALIBRATION AND ALIGNMENT OF PSD FOR THE NuSTAR SPACE MISSION
= Mechanical reference point
2011
Fig. 12. Exaggerated sketch of mounting a PSD chip with large positional tolerance relative to the mechanical reference.
= Screw to attach the PCB = Focal plane detector = Chip carrier = Printed circuit board = Mechanical structure Fig. 11. Example of a PSD chip mounted perfectly relative to a mechanical reference.
Fig. 13.
PSD chip has been tapped into place.
(1). The calibration is applied to the measured point as shown below: X Corrected = YCorrected =
X Orbit PSDDimension
+ C O R X (X Orbit , YOrbit )
YOrbit PSDDimension
X Scalefactor + C O R X (X Orbit , YOrbit )
(5)
YScalefactor VI. PSD A LIGNMENT
In the NuSTAR application, the photosensitive area of the PSD detector has to be located relative to mechanical reference points (the mounting feed of the chassis). One solution is to specify stringent requirements on 1) mounting the PSD chip relative to the chip carrier, 2) soldering the chip carrier onto the Printed Circuit Board (PCB) and 3) installing the PCB to the mechanical structure of the subsystem. In Figure 11 is shown a sketch of a PSD chip mounted relative to a mechanical reference with high positional accuracy. The PSD is fragile and therefore should not be physically touched by any measurement tool. An optical Coordinate Measuring Machine (CMM) was used to position the PSD relative to mechanical reference points. This approach eliminates all requirements on positional tolerances. The only requirement is that the PCB is manufactured with oversized holes. An exaggerated sketch of this situation is shown in Figure 12. The sketch shows very loose tolerances on mounting the PSD in the chip carrier, loose tolerance on soldering the chip carrier to the PCB and finally large tolerance on where the mounting screws are located. The PCB is held with large screws and over sized holes. The PCB is mounted loosely so it can move freely. The optical CMM measures the mechanical reference points. Based on these measurements, the desired positions of the optical detector corners are calculated. The optical CMM is commanded to go to the position where one PSD photo sensitive
Fig. 14. PSD chip mounted on the PCB. The PCB is attached to the structure with nine screws in oversized holes (>1 mm wriggle room) and two pins (at 3 and 9 o’clock).
area corner is supposed to be. This is indicated with the cross hairs in the Figure 12. Using a tapping tool (e.g. orange stick) the PCB is manually tapped around until the corner of the PSD is at the crosshairs of the optical CMM. The CMM is commanded to another corner, and the process is repeated a number of times until all corners of the PSD are within a distance of 10-30 microns of the required position. The situation is sketched in the Figure 13 (the Figure also shows the tapping tool and where to tap). At this point a slight torque is applied to the fasteners of the PCB so that the PCB can still move. The PCB location is adjusted again with the tapping tool. This process is repeated 3-4 times until the final torque is achieved. The oversized mounting holes are then filled with a liquid bonding agent to secure the board in position (not shown in the sketch). 10–30 microns mounting accuracy was achieved utilizing this method. Figure 14 shows the actual PSD chip relative to the mechanical reference points (the center of the 4 mounting holes on the outside of the mechanical structure). The PCB is mounted with 9 oversized screws and 2 positions for liquid pinning of the board to the structure. Figure 15 shows the actual PCB on
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Fig. 15. PCB with the PSD is mounted in an optical CMM. The structure itself is clamped down, but the PCB can move freely in the beginning of the alignment process.
the optical CMM. The described alignment procedure aligns the physical center of the PSD photosensitive area to the chassis. This is required in order to maximize the operational range of the PSD chip. In other words, the alignment is not related to the calibration described in Section V. However, it should be emphasized that the geometric center of the PSD chip is not coincident with the signal center of the PSD chip (signal center is the position where the X1 and X2 signals and Y1 and Y2 signals are the same). This is caused by offsets in the amplifier circuitry and imperfections in the PSD chip. VII. C ONCLUSION PSD chips have been space qualified for the NuSTAR space mission. The PSD chips have been qualified though a number of tests. Final flight chips were selected as the PSD chips with the lowest and most stable dark current over long duration tests. The PSD chips were not radiation tested. The PSD chips were calibrated by slewing a laser spot in a rectangular grid with ∼6000 positions. The PSD chip has a linear response to better than 80 microns over the central 14 mm of the chip. This calibration was performed at different temperatures, so it was possible to estimate the temperature expansion of the chip. Also, the photo sensitive area of the PSD chip was aligned relative to a mechanical reference point in an optical CMM machine. The actual position of the PSD chip relative to the laser spot is determined on-orbit where the X-ray observatory observes a bright X-ray with known celestial coordinates. R EFERENCES [1] F. A. Harrison, S. Boggs, F. Christensen, W. Craig, C. Hailey, D. Stern, W. Zhang, L. Angelini, H. An, V. Bhalereo, N. Brejnholt, L. Cominsky, W. R. Cook, M. Doll, P. Giommi, B. Grefenstette, A. Hornstrup, V. M. Kaspi, Y. Kim, T. Kitaguchi, J. Koglin, C. C. Liebe, G. Madejski, K. K. Madsen, P. Mao, D. Meier, H. Miyasaka, K. Mori, M. Perri, M. Pivovaroff, S. Puccetti, V. Rana, and A. Zoglauer, “The nuclear spectroscopic telescope array (NuSTAR),” Proc. SPIE, vol. 7732, no. 1, pp. 77320S-1–77320S-9, 2010.
[2] F. A. Harrison, F. E. Christensen, W. Craig, C. Hailey, W. Baumgartner, C. M. H. Chen, J. Chonko, W. R. Cook, J. Koglin, K.-K. Madsen, M. Pivavoroff, S. Boggs, and D. Smith, “Development of the HEFT and NuSTAR focusing telescopes,” Experim. Astron., vol. 20, nos. 1–3, pp. 131–137, 2005. [3] D. I. Harp, C. C. Liebe, W. Craig, F. Harrison, K. KruseMadsen, and A. Zoglauer, “NuSTAR: System engineering and modeling challenges in pointing reconstruction for a deployable X-ray telescope,” Proc. SPIE, vol. 7738, pp. 77380Z-1–77380Z-12, Jun. 2010. [4] C. C. Liebe, J. Burnham, R. Cook, B. Craig, T. Decker, D. I. Harp, B. Kecman, P. Meras, M. Raffanti, C. Scholz, C. Smith, J. Waldman, and J. Wu, “Metrology system for measuring mast motions on the NuSTAR mission,” in Proc. IEEE Aerosp. Conf., Big Sky, MT, Mar. 2010, pp. 1–11. [5] C. C. Liebe, A. Abramovici, R. K. Bartman, J. Chapsky, L. Chapsky, K. Coste, and R. Lam, “Optical metrology system for radar phase correction on large flexible structure,” in Proc. IEEE Aerosp. Conf., Big Sky, MT, Mar. 2008, pp. 1–7. [6] R. M. Duren and C. C. Liebe, “The SRTM sub-arcsecond metrology camera,” in Proc. IEEE Aerosp. Conf., vol. 4. Big Sky, MT, Mar. 2001, pp. 42037–42046. [7] P. Meras, M. Cooper, P. Dillon, S. Forouhar, I. Gontijo, C. C. Liebe, and A. Shapiro, “Qualification and selection of flight diode lasers for the NuSTAR space mission,” in Proc. IEEE Aerosp. Conf., Big Sky, MT, Mar. 2011, pp. 1–11. [8] M. Juretzko and E. Richter, “Geometrical survey of compact antenna test ranges using laser tracker technology,” in Proc. 3rd IAG/12th FIG Symp., Baden, Switzerland, May 2006, pp. 1–10. [9] D. H. Parker and J. M. Payne, “Metrology system for the green bank telescope,” in Proc. ASPE Annu. Meet., 1999, pp. 21–24. [10] R. E. Bowers, “Estimation algorithm for autonomous aerial refueling using a vision based relative navigation system,” M.S. thesis, Dept. Aerospace Eng., Texas A&M University, College Station, 2005. [11] S. Hensley, E. Chapin, A. Freedman, C. Le, S. Madsen, T. Michel, E. Rodriguez, P. Siqueira, and K. Wheeler, “First Pband results using the GeoSAR mapping system,” in Proc. IEEE Aerosp. Conf., vol. 1. Sydney, Australia, Jul. 2001, pp. 126–128. [12] K. K. Gunnam, D. C. Hughes, J. L. Junkins, and N. Kehtarnavaz, “A vision-based DSP embedded navigation sensor,” IEEE Sensors J., vol. 2, no. 5, pp. 428–442, Oct. 2002.
Carl Christian Liebe received the M.S.E.E. and Ph.D. degrees from the Department of Electrophysics, Technical University of Denmark, Kongens Lyngby, Denmark, in 1991 and 1994, respectively. He has been with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, since 1997, where he is currently an Optical Engineer with the Active Optical Sensing Group. He is the Systems Engineer for the NuSTAR metrology system.
Bruce W. Bauman has been designing and building custom photodetectors for over 30 years. He has been with Pacific Silicon Sensor, Inc., Westlake Village, CA, for the last ten years, where he is Chief Engineer for NuSTAR was his second detector project working with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, having designed and provided detectors for LAMP back in 2003.
LIEBE et al.: DESIGN, QUALIFICATION, CALIBRATION AND ALIGNMENT OF PSD FOR THE NuSTAR SPACE MISSION
Jerry Clark is a Technical Specialist of precision measurement and mechanical alignment with the Quality Assurance Section (512), Jet Propulsion Laboratory (JPL), California Institute of Technology, Pasadena, CA. He has been an ASQ Certified Quality Engineer at JPL since 2000, the Technical Lead Person of the Procurement Quality Assurance, Receiving Inspection, and Mechanical Inspection Groups, and currently with the Optical Metrology and Alignment Group. He is experienced with the practical application of optical and touch probe coordinate measuring machines (CMMs) and laser tracker systems. He received a NASA Spaceflight Awareness Award for the creative application of CMM systems in optical bench alignments in 2002.
Walter Cook received the B.S. and M.S. degrees from the Stevens Institute of Technology, Hoboken, NJ, and the Ph.D. degree from the California Institute of Technology, Pasadena, in 1972 and 1980, respectively, all in physics. He is with the Space Radiation Laboratory, California Institute of Technology. He is the Chief Electronic Engineer for the NuSTAR Instrument.
Mark Cooper received the B.S. degree in electrical engineering from the City University of New York, New York, the M.S. degree in electrical engineering, from the Massachusetts Institute of Technology, Cambridge, and the Ph.D. degree in physics from the University of California, Berkeley. He currently supports several space projects and is the PEM Parts Specialist with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena. He has published several articles in Physical Review and the Journal of Applied Physics, and directed development of solid state surge arrestors, research on radiation effects in IEEE journals, and articles on part reliability infant mortality analysis for space applications.
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Patrick Meras, Jr. received the M.S.E.E. degree from the Department of Electrical Engineering, University of Southern California, Los Angeles, in 2005. He has been with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, since 2005, where he is currently a Staff Member with the Active Optical Sensing Group. He is the Laser Engineer for the NuSTAR metrology system.
Branislav Kecman received the B.Sc. degree from the University of Belgrade, Belgrade, Serbia, and the M.Sc. degree from the California Institute of Technology, Pasadena, in 1987 and 1989, respectively, all in electrical engineering. He is with the Space Radiation Laboratory, California Institute of Technology. He is the Cognizant Engineer for the NuSTAR electronics.
Hiromasa Miyasaka received the B.S. and M.S. degrees in physics from Shinshu University, Nagano, Japan, and the Ph.D. degree in physics from Saitama University, Saitama, Japan, in 1995, 1997, and 2000, respectively. He has been with the Space Radiation Laboratory, California Institute of Technology, Pasadena, since 2004. He is currently a Staff Scientist for the NuSTAR science and the focal plan detector developments.
Kristin Kruse Madsen received the M.S. and Ph.D. degrees in astrophysics with the University of Copenhagen, Copenhagen, Denmark, in 2007. She has been with the Space Radiation Laboratory, California Institute of Technology, Pasadena, since 2007. She is a part of the NuSTAR instrument team.
Christopher Scholz received the B.S. degree from the University of California, Berkeley, in 1982. He built electronics assemblies for balloon, sounding rocket, and satellite payloads. He is currently a Quality Assurance Engineer with U. C. Berkeley Space Sciences Laboratories. He has been involved in many missions such as thermal emission imaging system – a suite of five satellites launched on a Delta II and cosmic origins spectrograph, which was launched on STS 125 space shuttle on Hubble Servicing Mission IV.
Peter Mao received the S.B. degree from the Massachusetts Institute of Technology, Cambridge, and the Ph.D. degree from the California Institute of Technology (Caltech), Pasadena, in 1994 and 2002, respectively, all in physics. He was with the University of California, Los Angeles, from 2002 to 2008, where he worked on the MegaSIMS experiment for NASA’s Genesis Mission. In 2008, he joined as a Staff Scientist at Caltech, where he worked on the NuSTAR mission.
Jack Sedaka received the B.S. degree in physics from California State University, Long Beach, in 1996. He has been with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, since 2006, as the Group Supervisor of mechanical inspection. He is certified by the American Society for Quality as an Inspector, an Engineer, the Manager of Quality/Organizational Excellence, and as a Six Sigma Black Belt. He has worked professionally in the field of quality for over 25 years.
