Spin-Polarized Electron Sources for Electron Microscopy
We offer custom-built, high-brightness, ultrafast polarized electron sources in a compact design suitable for table-top installations or integration with existing SEM and SPLEEM columns.
Our sources use GaAs nano-emitter cathode technology to deliver femtosecond polarized beams with electron-microscope-scale beam quality. By selecting emitters of different sizes within a single cathode, users can tailor the trade-off between energy spread, emittance, pulse length, and beam current for their application.
Nano-emitter Array Cathodes
A key innovation in our design is the use of lithographically patterned GaAs nano-emitter photocathode arrays with emitters of varying sizes, down to about 200 nm.
This allows users to select the emitter that provides the best balance of beam current, quality, time resolution, and energy spread.
The photocathode concept
The cathodes are fabricated by applying a thin platinum layer onto a GaAs wafer (with an intermediate adhesive layer such as chromium).
The platinum layer is then lithographically patterned and etched to create micro- and nano-scale holes, exposing the GaAs underneath.
Example cathode SEM images
Features
Fully customizable system built to your specifications, including mechanical and beamline interfaces
UHV-compatible design constructed from materials designed appropriate for ultra-high vacuum operation
Custom oven included for efficiently surrounding the gun vessel
GaAs nano-emitter array cathode
Compact DC gun assembly suitable for tabletop installation
In-situ cathode activation using Cs dispensers
Laser delivery optics with rear (transmission-mode) coupling
Optional ports for front illumination
Beam steering and focusing stage (application dependent)
Optional load-lock system for frequent cathode swaps, with storage for multiple cathodes
Prototype with load-lock system and additional ports for front-side illumination of the cathode:
Key Parameters
| Vacuum level in gun | 10−12–10−11 Torr |
| Gun voltage | 15–30 kV (custom designs up to several hundred kV available) |
| Average beam current | ~1 nA |
| Bunch repetition rate | ~100 MHz |
| Bunch charge | ≤ 100 e− |
| GaAs emitter diameter | as small as 200 nm |
| Drive laser wavelength | 780 nm |
| Spin polarization | up to 40% |
| Transverse norm. emittance | 10–100 pm |
| RMS bunch length | as low as 100 fs |
| RMS energy spread | ~200 meV |
These parameters are based on active development work.
Built to Your Specs
We offer custom builds for R&D deployments and microscopy applications. Tell us your beam requirements and mechanical constraints, and we’ll propose a configuration optimized for your experiment or microscope column.
Contact us for a quote, to discuss your application, or with any questions!
3D Render of a prototype tabletop polarized source system