Mirror Alignment of the FACT telescope

Our FACT telescope has a multi mirror reflector of 30 single hexagonal mirror facets. To feed our G-APD camera with high resolution images, the reflector's mirrors have to be aligned. The mirror alignment is about the mirror's position and it's orientation.

Mirror Position

The mirror position is fixed in directions perpendicular to the telescope's optical axis by the honeycomb grid of the mirror facets. The crucial position left is the distance of the mirror's centre to the centre of the camera window. The distance between the mirror centre and the camera window centre is determined using a LASER distance meter. As decided on our General Meeting 2014 in Dortmund, we will set this distances to obtain a hybrid reflector. A hybrid reflector is partly a Davies Cotton design and partly a Parabola design. This was chosen to improve temporal resolution.

Status of Hardware for position determination

Item	designed	ordered	machined	note
Optical table	100%	100%	75%	weight reduction
45DEG mirror	100%	-	100%	plane,front coated mirror
45DEG mirror mount	25%	-	0%	plane,front coated mirror
Protection shield	0%	0%	0%	to protect the G-APD window
LASER DM (distance meter)	-	100%	-	Bosch PLR 50, 2x (one spare)
LASER DM camera	-	100%	-	Sony CCD analog for remote readout
LASER DM monitor and transmission	-	100%	-	Monitor for remote LASER DM readout
LASER DM mount	50%	100%	25%	motorized mount for radio remote control
2x actuators	100%	100%	100%	6V DC motor 1000:1 for rotation and altitude
Radio remote control 2Ch.	-	100%	-	40Mhz analog FM 2Ch. RC transmitter to remote control the LASER DM
Battery packs	-	100%	-	6V and 9.6V AA GP recyko cells
Battery charger	-	0%	-	charger for AA batteries
small stickers ~2cm	-	0%	0%	A sticker for each mirror's centre
thin rope	-	0%	0%	to position stickers

Mirror Orientation

The mirror orientation will be dealt using the Bokeh approach. There is a video of the Bokeh technique performed on Mini FACT in the \home of the GATE PC on La Palma.

Status of Hardware for orientation determination

Item	designed	ordered	machined	note
Lamp	0%	0%	0%	A bright, punctual (<5cm) light source
2x 3m tripods	-	0%	-	A tripod to place the lamp, camera or the cross line LASER on (photo thread)
tripod	-	0%	-	A tripod to support the G-APD camera housing while alignment at zd=90DEG
2x Cross line lasers	-	100%	-	self level cross line lasers to set the optical table
Bokeh plate	0%	0%	0%	A plate to place the Bokeh template on (MDF 40cm diameter)
Printer	-	0%	-	A printer to print the Bokeh template (DIN A4 inkjet)