Cryostat_SOW.docx

STATEMENT OF WORK / SPECIFICATIONS

CLOSED-CYCLE OPTICAL CRYOSTAT FOR MICROSCOPY

DESCRIPTION: This system consists of a close-cycle cryostat for optical microscopy that has very low vibration at the sample and can reach a temperature of 5 K or below at the sample. It must include the compressor, cryostat, control electronics, and integrated microscope objectives. It must also include positioners within the cryostat to move the sample relative to a microscope objective. Two high NA objectives must be included with the system that can be mounted inside the cryostat with no windows between the objective and the sample. The cryostat must be designed such that a permanent magnet outside the cryostat can apply a magnetic field of 100 mT or higher along the optical axis of the system.

REQUIREMENTS:

· Sample temperature from 5 K or below to 350 K with temperature control electronics and the ability to computer control the temperature.

· Temperature stability: 50mK

· Vibration levels at the sample of 50nm with the sample mounted on positioners

· Cool down time to ~5K : ~3 hours or less

· Two microscope objectives that can be mounted one at a time inside the cryostat with no windows between the sample and objective. Both objectives must have transmission above 55% from 400nm to 1000nm and little chromatic aberration over this range. It must be possible for the user to switch between these objectives. One objective must have an NA of 0.9 or higher with a working distance of at least 300m, and the second should have a lower NA of about 0.75 and a working distance of 3mm or more.

· Sample positioners that function at low temperatures that can move the sample in the X, Y, and Z dimensions over 5 mm, with typical step sizes of about 10 nm. Positioner control electronics must be included.

· Electrical feedthroughs:

· Feedthroughs for the sample positioners

· 4 or more feedthroughs for sample wiring

· 2 microwave/RF coax feedthroughs with the coax terminated in the sample space. This wiring must operate at frequencies up to 5 GHz.

· The cryostat must be designed such that a permanent magnet or electromagnet outside the cryostat can be positioned close enough to the sample to produce a magnetic field of at least 100 mT. This should mean that the magnets can be within 0.75” of the sample. The magnet does not need to be included with the system. The direction of the magnetic field should be oriented along the optical axis defined by the microscope objective but there should be flexibility to change the field direction by about 60 degrees.

· The compressor must be air cooled and consume less than 3kW of electrical power

· The sample mount(s) and the sample space must be able to accommodate either a thin sample of about 0.5mm thickness or a chip carrier that is 2mm thick with leads sticking out an additional 3mm. It must also be able to accommodate samples with a lateral size of up to 12 × 12 mm or more.