| Toroidal Grating & Flat Field Instruments for the Soft X-ray and Extreme Ultraviolet (EUV)
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McPherson, Inc. produces spectrometers for work in the Extreme Ultraviolet and Soft X-ray wavelength regions. For special applications, consider using a dedicated wavelength range of analysis. Examples when this may be practical include the development of laser excited Xenon plasma at 13.5-nm for Extreme Ultraviolet Lithography (EUVL) light sources, and diagnostics of the short lifetime plasmas formed in tokamak devices. In these cases, use of a flat field or aberration corrected spectrometer may be an advantage.
The flat field toroidal grating instruments works over a fixed wavelength range. The prescription of the toroid and any aberration correction designed into the optic, will determine the range of optimum use. Due to intensive design and difficult optical fabrication selection of gratings is limited. If there is a grating available for your wavelength of interest, you are in luck! Work with a relatively simple optical system that delivers good imaging and fair spectral resolution. These instruments also allow you to use a CCD for direct detection of the high-energy spectra. Microchannel plate (MCP) intensifiers can be reserved for those systems requiring gating.
For greater flexibility, or astrophysics instrument calibration (for example) consider the Rowland circle design grazing incidence system Model 248/310G. It provides most flexibility with respect to wavelength range. Many grating choices are available and it delivers excellent spectral resolution.
Specifications
McPherson Model 251 Toroidal Grating Flat Field Spectrometer:
Flat field aberration corrected toroidal grating spectrometer fills a 40mm focal plane ideal for microchannel plate intensifiers. Compact and versatile this is a workhorse instrument. Many of our customers use these at tokamak plasma research centers. Versions exist with 2 and 3-grating turrets, back-to-back diffraction gratings for simultaneous, dual-range monitoring, rocking mechanisms to scan large plasma sections and more. Please inquire.
| Deviation Angle Degrees |
G/mm | Resolution (nm) |
Focal Plane Width (mm) |
Spectral Range (nm) |
Spectral Range (eV) |
| 140 | 2105 | 0.05 | 40 | 9.5 to 32 | 130 to 39 |
| 140 | 450 | 0.10 | 40 | 10 to 110 | 124 to 11 |
| 140 | 290 | 0.16 | 40 | 15.5 to 170 | 80 to 7 |
McPherson Model 343 Toroidal Grating Monochromator:
Toroidal grating monochromator requiring grating rotation to change wavelengths. Fixed slit positions. Available with a 2-grating turret to increase wavelength range capability. Aberration corrected for better spectral resolution. Data Sheet for the toroidal grating monochromator Model 343 available here
| Deviation Angle Degrees |
G/mm | f/no. | Resolution (nm) |
Spectral Range (nm) |
Spectral Range (eV) |
| 142 | 275 | 10.9 | < 1.3 | 50 to 300 | 4 to 25 |
| 142 | 550 | 10.9 | < 0.6 | 15 to 150 | 8 to 82 |
| 142 | 550 | 10.9 | < 0.3 | 10 to 50 | 25 to 124 |
McPherson Model 251 toroidal grating spectrometer with dual, parallel optical / detection channels allowing simultaneous collection of high resolution and survey spectra. This is a good example of a purpose built instrument. The parallel detection channels collect more data during brief plasma formation in thermonuclear fusion experiments.