IR camera 1

RATIR IR camera

• Two H2RG detectors 2048x2048 pix2

• Imaging bands:• detector 1:

• Z 830- 925 nm• Y 970-1070 nm ( UKIDSS Y and Z bands, http://www.ukidss.org/technical/instrument/filters.html)

• detector 2:• J 1170-1330 nm• H 1490-1780 nm

• Plate scale 0.2”/pix -- 6.8’x6.8’ FOV (0.3”/pixel w. demagnifying optics)• Image quality: FWHM ≤ 0.3” (derived requirement)

IR camera 2

Mechanical structure approach:decouple VIS from IR

VIS

IR

The most important results of the modeling (FEA):- displacements are negligible and will not affectimaging during typical camera operation.

IR camera 3

IR camera layout

Dichroic 1 to VIS channels

VIS 1Dichroic 2 to VIS 2 (out of plane)

IR dewar with IR det ZY and JH

Issues:

- tight space, thus difficulty with baffling- significant thermal background, possibly variable- poor control of scattered light

- oversampled image (x 2.5 linear, 6 times by area), thus longintegration times required to achieve background limitedregime, which is essential (if not critical) for GRB followup- small camera FOV

IR camera 4

IR camera withpowered optics

Dichroic 1 to VIS channels

VIS 1

Dichroic 2 to VIS 2 (out of plane)

Folding mirror

Cold Lyot stop -pupil location

Purpose:

- demagnify image by factor 1.5 :- 10’ x 10’ FOV- 0.3”pixel plate scale- factor of 2 gain in acquisition time (DetLim)

- create telescope pupil image:- eliminate (or greatly reduce) thermal bgnd- better control of ghosting- reduced scattered light

Optical design level is between concept anddesign, requires more detailed development. Weare actively working on finalizing optical designof the IR camera lens assembly.

IR camera 5

Ghosts

2MASSGSFC/WIRO cameraMrk 421

Ghosts(most likely flat surfaces in || beam)

IR camera 6

Camera functional bloc diagram

Software!!!

IR camera 7

Cryo systemH2RG detectors require to be cooled to LN2temperature for optimal performance.Cryomechanical cooler system is more reliable,thermally stable and requires less maintenance.

Cryostat (as currently baselined):• compressor: CH4 (Sumitomo)• cryocooler: CH104 (single state cryocooler)• cooling capacity 30 W at 77K• dewar assembly total weight: 64Kg• time between services: 13,000 hours• antivibration dempers (*)• watercooled (alternative CTI model - aircooled)

Operation:• power 3KW, 208V• compressor will be located outside of the dome

Status:• 2 quotes received (from IRLabs and ColdEdge Cryogenics)• delivery 3 month after order is placed• will be refined as needed depending on windows material and optics

vibration dampers

IR camera 8

Cryo MechanismsThere is a single focusing mechanism in the IR camera,the second detector will be focused using secondarymirror.

Cryogenic motors ARSAPE AM1524Used extensively in BAM, G-Wy IRcam, microshutters

Motors

Stages:

Status: available

CryogenizedNewark

CryostagesIRlabs

IR camera 9

Cryo details

vibration dampers

OFC cold straps

Cold space

Cold window - sapphire Dewar window - glass (TBR)

• Both windows are tiltedby ~4-5 deg to move theghosts out,• both windows are ARcoated

IR camera 10

Electronics: detectors H2RG• Detector

• detector drivers• detector data readout

Status: in the process of ordering

IR camera 11

Electronics• “Housekeeping”:

• temperature monitoring/control• pressure monitoring• focusing

• NI motor drivers

Status: available

Focusing/FW SW interface

LakeShore 340 temp. controller

Pressure monitor: requires vac gaugeorder

IR camera 12

Electronics: dewar cryo-harness• Internal harness:

• vaccum round connectors Tekdata manganine cables (woven)• detector drivers• detector data readout

MDM connectors

vacuum connectors

Status: available now;boards can be re-done to adapt todifferent MDM connectors

IR camera 13

SoftwareCryostat (as currently baselined):• Temperature sensors/control: available• Pressure monitorining : available• Focus/positioning : available

• Detectors DAC : requires work and interfaces to the existingTeledyne software

IR camera 14

Summary• design is modeled after the existing Goddard-Wyoming IR camera• optics: the existing concept has to be developed into a real design• most of the system control/monitor components are readily available• camera control software modules exist and can be adapted• data and communication interface software will require significantefforts

IR camera 15

Goddard-Wyoming IR camera

• 2’x2’ FOV• InSb (5.5um) detector (2562)• Cryomech cooler • 16K detector operation• 2 filter wheels, 10 positions/FW• detector focusing mechanism

IR camera 16

Test facility available

10K CTI cryocooler (WMAP legacy)