TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Chapter 7
7.4.2 Apodizing Masks and Stops
Scope
HEBS and binary masks for both focal plane and pupil plane configuration will be fabricated and
tested, including the new 8 th -order masks, which have been predicted to yield lower sensitivity to
aberrations as well as better error budgets due to improved tolerances. Basic characteristics of
mask materials and devices and their spectral dependence will be measured precisely with a
dedicated component-level test setup being developed at JPL. The schedule for the apodizing
masks and stops is given in Table 7-3.
State of the Art TRL 3
Candidate masks have been fabricated and tested on the HCIT. More promising designs are now
being prepared.
Table 7-3. Apodizing Masks and Stops Schedule
Planned
Completion
Date
Planned Activities Performance Targets TRL
Pre-Phase A
Q1 FY05
Fabrication of initial set of
candidate masks; fabrication and
evaluation of HEBS and binary
masks
Compare performance impact of each type of
mask on HCIT.
3
Q4 FY05
Q4 FY06
Q4 FY06
Iterate fabrication of candidate
masks, based on performance
results. Fabricate and test 8 th
order masks in both binary and
HEBS implementations.
Fabricate and test silicon type
masks. Test and compare pupil
plane masks and focal plane
masks.
Incorporate analysis results to
improve design and fabrication.
Measurement of candidate masks at component
level to quantify and control fundamental
properties such as optical density, amplitude
variations and phase retardation/advance including
wavelength dependence with better than ±1%
measurement precision. A dedicated test setup and
methodologies for such precision measurements
will be fully developed.
3-4
Phase A
Optimization of apodization
functions and fabrication
methods. Mask set delivery.
Receive masks consistent with 10 -9 contrast
requirement.
4-5
Phase B
Summary report on mask design
and fabrication. Mask set
delivery.
Receive masks consistent with 10 -10 contrast
requirement.
6
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