A document discusses a null lens assembly that allows laser interferometry of 60 deg. slumped glass mirror segments used in x-ray mirrors. The assembly consists of four lenses in precise alignment to each other, with incorporated piezoelectric nanometer stepping actuators to position the lenses in six degrees of freedom for positioning relative to each other

Robinson, David W.

NASA Technical Reports Server

Books & Reports
Silicon-Germanium Voltage-
Controlled Oscillator at 
105 GHz
A group at UCLA, in collaboration
with the Jet Propulsion Laboratory, has
designed a voltage-controlled oscillator
(VCO) created specifically for a com-
pact, integrated, electronically tunable
frequency generator useable for submil-
limeter-wave science instruments operat-
ing in extreme cold environments. The
VCO makes use of SiGe heterojunction
bipolar transistors (HBTs). The SiGe
HBTs have a 0.13-micrometer emitter
width. A differential design was used
with two VCOs connected to form a
quadrature signal. A 2.5-V supply is re-
quired to power the circuit. A cross-cou-
pled CMOS pair is used for emitter-de-
generation of the SiGe HBTs, and the
design uses coupled load and base in-
ductors. The circuit oscillates at 105
GHz. A linear superposition of VCOs has
been designed to achieve four times the
oscillation frequency of the fundamen-
tal oscillator.
This work was done by Alden Wong, Tim
Larocca, and M. Frank Chang of UCLA , and
Lorene A. Samoska of Caltech for NASA’s Jet
Propulsion Laboratory. Further information is
contained in a TSP (see page 1).NPO-47116
Estimation of Coriolis Force
and Torque Acting on Ares-1
A document describes work on the ori-
gin of Coriolis force and estimating Cori-
olis force and torque applied to the Ares-
1 vehicle during its ascent, based on an
internal ballistics model for a multi-seg-
mented solid rocket booster (SRB).
The work estimates Coriolis force
and torque applied to the vehicle dur-
ing its ascent. Maveric flight simulation
software was used to produce the re-
quired angular velocity data for the
Coriolis force and torque computa-
tions. For the simulation of gas move-
ment in SRB, software was developed
using a dynamical model of internal
ballistics of the five-segmented SRB.
Also included in the work are a study
and estimate of Coriolis force and
torque applied to the rocket due to SRB
nozzle movement. For calculation of in-
ternal ballistics, Coriolis force, and
torque computations, MATLAB soft-
ware was used.
Coriolis force and torque were calcu-
lated and applied to Ares-1 during its as-
cent. Two cases were considered: Corio-
lis force and torque applied to the
rocket originating from gas movement
in SRB, and Coriolis force and torque
originating from exhaust gas movement
in SRB nozzle. Coriolis force and torque
are the largest during the first 20 sec-
onds after the launch when rocket angu-
lar velocity is large. SRB Coriolis force is
about 5.4 times larger than nozzle Cori-
olis force, and SRB Coriolis torque is
about 2.8 times larger than the nozzle
Coriolis torque at the time t=10 seconds.
The inclusion of flexible rocket model
does not provide a significant change to
the results of Coriolis force and torque
computations in comparison with a rigid
rocket model.
This work was done by Ryan M. Mackey
and Igor K. Kulikov of Caltech; Vadim
Smelyanskiy and Dmitry Luchinsky of Ames
Research Center; and Jeb Orr of BD Systems
Inc. for NASA’s Jet Propulsion Laboratory.
Further information is contained in a TSP
(see page 1).
The software used in this innovation is
available for commercial licensing. Please con-
tact Daniel Broderick of the California Insti-
tute of Technology at danielb@caltech.edu.
Refer to NPO-47326.
Null Lens Assembly for 
X-Ray Mirror Segments
A document discusses a null lens as-
sembly that allows laser interferometry
of 60° slumped glass mirror segments
used in x-ray mirrors. The assembly
consists of four lenses in precise align-
ment to each other, with incorporated
piezoelectric nanometer stepping actu-
ators to position the lenses in six de-
grees of freedom for positioning rela-
tive to each other. 
Each lens is first installed and epoxied
into a 410 stainless steel “cell.” The outer
housing is designed to allow five degrees
of freedom of the lens. The cell is placed
onto a 3/8-in. (≈ 9-mm) ball bearing in
the base of the housing, which provides
a pivot point for the rotations, and al-
lows slight x and y translations (microns)
by allowing the cell to slide against it.
Rotations are accomplished by 5 com-
mercial picomotors that push on the cell
in 30-nanometer increments. Spring
plungers on the opposite side of the cell
from the picomotors secure the cell in
the housing. 
The 410 stainless steel is used for the
cell, baseplate, and rails because it has a
low CTE (coefficient of thermal expan-
sion) relative to most other metals. It is
used exclusively in the “growth path” of
the optical assembly so that when bulk
temperature changes occur in the lab,
the lenses will move a consistent amount
apart from each other (which is a less
sensitive factor in alignment), but will
not tilt or rotate (alignment is very sensi-
tive to rotations).
This work was done by David W. Robinson
of Goddard Space Flight Center. Further infor-
mation is contained in a TSP (see page 1).
GSC 15790-1
High-Precision Pulse 
Generator
A document discusses a pulse genera-
tor with subnanosecond resolution im-
plemented with a low-cost field-pro-
grammable gate array (FPGA) at low
power levels. The method used exploits
the fast carry chains of certain FPGAs.
Prototypes have been built and tested in
both Actel AX and Xilinx Virtex 4 tech-
nologies. In-flight calibration or control
can be performed by using a similar and
related technique as a time interval
measurement circuit by measuring a pe-
riod of the stable oscillator, as the delays
through the fast carry chains will vary as
a result of manufacturing variances as
well as the result of environmental con-
ditions (voltage, aging, temperature,
and radiation).
This work was done by Richard Katz and
Igor Kleyner of Goddard Space Flight Center.
Further information is contained in a TSP
(see page 1). GSC- 15831-1
NASA Tech Briefs,  January 2011 41
https://ntrs.nasa.gov/search.jsp?R=20110003027 2019-08-30T14:18:08+00:00Z


Null Lens Assembly for X-Ray Mirror Segments

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server