OptistatDry: Temperature Controlled Sample-in-Vacuum Measurement Environments for Spectroscopy

The OptistatDry for spectroscopy consists of a range of compact cryostats with optical access cooled by a closed cycle refrigerator. This cryogen free (Cryofree®) cryostat is part of Oxford Instruments’ high performance Optistat series.

It is designed to cool samples to helium temperatures without using liquid cryogens. This provides major benefits such as ease of use and lower operational costs. The system enables electrical and optical measurements to be performed on samples.

A two-stage Gifford McMahon (GM) refrigerator supplied by Sumitomo Heavy Industries (the RDK-101D cold head and HC-4 compressor) is the cooling source for the cryostat. The sample cools in a direct conductive thermal path to the second stage of the refrigerator.

The refrigerator’s first stage is used to cool a radiation shield, which reduces the radiative heat load to the sample region and to the second stage of the refrigerator.

The lower tail section of the cryostat (the window block) is made so that it is easy to remove and replace the sample mounting platform, when the cryostat has been warmed to room temperature with the cooler switched off and the cryostat vacuum let up to atmospheric pressure.

The sample mounting platform has two key variants. The first is a simple nickel plated copper blade platform for conducting optical experiments, with limited or no electrical measurement requirements. The second is a circuit board style platform (puck) designed for combined electrical/optical transport experiments.

Key Benefits

The OptistatTMDry BLV model offers the following benefits:

Simple to Use

  • The sample can be changed via the unique load port in a fast and simple manner, this avoids the need to remove the cryostat from the optical bench and re-align customer’s optics after every single sample change
  • Liquid cryogens are not required
  • Air or water-cooled compressors are provided; single phase electrical power makes the system simple to install in all regular laboratory environments

Versatile

  • Can be interfaced with all types of optical benches; the feet match both Metric (25 mm spacing) and Imperial (1 inch spacing)
  • Ideal for a broad range of experiments and varied spectroscopy techniques (UV/VIS reflectivity and absorption, FTIR, Fluorescence, Raman scattering, Electrical transport measurements, Photoluminescence, THz spectroscopy, Electroluminescence, Ultrafast spectroscopy, etc.)

Upgradeable

  • Designed with a modular concept that allows the cryostat to progress along with the specific experiment, allowing users to start with a basic system and as experimental requirements change, to be able to upgrade to extra functionalities at a later date, for instance, integrate additional wiring, windows, and different sample holders
  • Broad range of different sample holders, windows and wiring options enable users to upgrade their system based on the progression of experimental requirements

Optical Excellence

  • f1 and large clear optical access are offered as standard
  • Consists of one window per optical access, a window in the OVC only; this makes the system especially suitable for customers who need to decrease absorption losses
  • Broad range of varying window materials are offered to match varying wavelengths; wedged windows and anti-reflection coatings are also provided

Specifications

The main specifications for the cryogen free OptistatDry - the BLV model are listed below:

  • Broad sample temperature ranging from < 3 K to 300 K
  • Cool-down time from ambient to 10 K in 120 minutes
  • Low vibration when used along with the optional stand, normally <10 µm RMS
  • Large sample space enables analysis of samples with an extensive range of different sizes and geometries
  • Improved optical access with f1 and a clear view of 28 mm diameter allows a large illumination area for measurements relating to the detection of low intensity light

Applications

The main applications of the OptistatDry – the BLV model are given below:

  • UV/visible spectroscopy - Experiments at low temperatures show the interaction between the vibrational modes and electronic energy levels in solids
  • Electrical properties - Electrical and optical measurements including I-V curves
  • Raman spectroscopy - Lower temperatures give rise to narrower lines related to the observed Raman excitations
  • Photoluminescence - At low temperatures, spectral attributes are sharper and more concentrated, thus increasing the amount of data available
  • Infrared spectroscopy - Low temperature IR spectroscopy can be used to measure alterations in interatomic vibrational modes and other phenomena, such as the energy gap in a superconductor below its transition temperature

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