Lastly, Gemini Senior Mechanical
Group Leader Gabriel Pérez com-
pleted the design of the interface
between the Toptica Laser Head
and the Beam Transfer Optics (BTO),
and it is now ready for fabrication.
— Manuel Lazo
‘Alopeke Settles in at
Gemini North
In October, Steve Howell and his
team will plan to commission a
new speckle instrument named
‘Alopeke. The instrument is to be
mounted on the Gemini North
telescope as a Gemini Visiting In-
strument. Speckle imaging is an
interferometric technique by which
telescopes can achieve diffraction-
limited imaging performance using Fourier
image reconstruction techniques with cam-
eras that are capable of reading out frames
at a very fast rate. The images, reduced us-
ing specialized software, allow scientists to
effectively “freeze out” the effects of atmo-
spheric seeing and perform the equivalent
of space-based imaging with ground-based
telescopes.
The design of ‘Alopeke is based on the Differ-
ential Speckle Survey Instrument (DSSI). The
original DSSI has been a popular Visiting In-
strument at Gemini since 2012. Making ob-
servations at both Gemini North and South,
DSSI has provided simultaneous diffraction-
limited optical imaging — Full-Width at Half-
Maximum (FWHM) ~0.02” at 650 nanome-
ters (nm) — of targets as faint as V ~16–17,
in two channels over a ~2.8” field-of-view.
The diffraction-limited resolution possible at
Gemini (0.016” FWHM at 500 nm or 0.025” at
800 nm), with no need for an adaptive optics
guide star or laser, offers unique scientific ca-
pabilities.
July 2017
Figure 5.
The most recent DSSI visit to Gemini South
was marred slightly by unstable weather,
but in the end, the team obtained data on a
large range of projects from follow-up vali-
dation of exoplanet candidates to a search
for close binary companions of exoplanet
host stars, as well as a study of the rate of bi-
narity in low mass star forming regions.
‘Alopeke is the contemporary Hawaiian
word for fox, and this name was chosen for
the newest member of the DSSI family be-
cause it is very agile and quick. The new
dual-channel instrument will have a larger
format than the previous version, modern
GeminiFocus
The Toptica Laser
Interlock System
Data Manager
screen. Angelic
Ebbers developed
it as part of the
Experimental
Physics and
Industrial Control
System (EPICS)
code to interact
with existing
parts of Gemini
South telescope’s safety
subsystems. It also
interacts with the safety
aspects and feedbacks
of the Toptica Systems;
Paul Collins developed the
latter in a Programmable
Logic Controller
environment.
Figure 6.
The design of the Toptica
Laser Beam Injector
Interface to the telescope
Beam Transfer Optics by
Gabriel Pérez.
17