 MCP BASICS
For over thirty years, PHOTONIS (formerly Philips Photonics, Galileo and Burle) has consistently set the standard in electron multipliers and related products. Today, an extensive R&D program coupled with unsurpassed expertise in microchannel plate (MCP) technology continues to deliver a succession of product and process improvements that push aside previous technology limits. This expertise is used to mass-produce MCPs for our image intensifier tubes as well as for a variety of custom scientific applications. This, plus the ability to meet your product requirements, makes Photonis the preferred choice of professionals the world over.
A microchannel plate (MCP) is an electron multiplier for detecting X-rays, ultraviolet radiation and charged particles. The output is a two-dimensional electron image which preserves the spatial resolution of the original input radiation, but with a linear gain up to 1000. This may be used for exciting a phosphor screen placed close to the output, giving a visual representation of the radiation pattern. Alternatively, the electron image can be read out by, for example, a wedge-and-strip or fast delay-line anode array.
Important features of MCPs are:
- high electronic gain
- immunity from magnetic fields
- fast response
- low noise
- low power consumption
- high spatial resolution
- small size and ruggedness
Each plate consists of an array of tiny glass tubes fused together to form a thin disc. Both faces of the disc are metal-coated to provide parallel electrical connections to all channels. In a vacuum, and with a potential difference (usually 800 to 1400 V) across the plate, each channel becomes a continuous dynode electron multiplier, operating on the same principle (electron avalanche) as its cousin - the single-channel electron multiplier.
Special MCP's
Micropore optics
Photonis has developed the first-ever square-pore radially-packed X-ray focusing MCP optics and is currently refining the technology with continued support by ESA. For special projects, options are available, such as a square-pore square-packed X-ray optics with pore sizes of 10 to 100 µm, plates with a thickness of several millimeters, formed with a spherical radius or with metal-coated pore walls for optimum reflectivity can be developed and supplied.
Curved-channel MCPs
The curved-channel MCP was invented by the Philips LEP laboratory 1973 and produced in our factory in Brive in 25 µm pore, 25 mm diameter for some time. It was seen as a new way to prevent ion feedback at high gain with preserved spatial resolution. The major application was invention of the Multi-Anode Multi-Array (MAMA) tube by Timothy et al. at the time.
Today, improved MCP readout arrangements in the form of "wedge & strip" anodes, fast delay-lines or Vernier anodes offer equal or better spatial resolution with the MCP stacks mentioned above. As the curved-channel MCPs were very difficult and costly to make in large formats they are only used for a few MAMA tubes, offered by competitors who copied the process after our patents expired.
History and References
PHOTONIS' microchannel plates (MCPs) were originally developed in the UK by the Philips Research laboratories in Redhill and went into production at the Philips (Mullard) factory in Mitcham. Two proprietary glass compositions were developed by the Philips glass laboratories in Eindhoven, The Netherlands, with different resistivities to optimise plate performance in second-generation image intensifier tubes, at that time the main purpose of the development.
Over the years, the demand for better spatial resolution in image intensifier tubes has driven down the pore size from 40 µm, through 25, 16 and 12.5 µm, to the present standards of 10 µm and 6 µm in MCPs for image intensifier tubes.
As soon as MCPs became available, they quickly found use in many scientific applications and especially in space research. Early co-operation with Mullard Space Science Laboratory (UK), Leicester University (UK), the Space Science Laboratory at University of California (USA) and the Smithsonian Astrophysical Observatory, Cambridge, MA (USA) are cornerstones that made MCPs for space research a successful complementary activity to the plates for image intensifier tubes. Today, our scientific microchannel plate activity draws on in-depth knowledge and large-volume production of MCPs for our image intensifier tubes.
For 25 years PHOTONIS' MCPs have been used in almost all space-borne instruments needing plates.Very soon, NASA will launch the prestigious Chandra X-ray Observatory (earlier named AXAF) with special MCPs from PHOTONIS in the Advanced Spectrometer.
To study the most distant objects in the universe, the MCPs must have an extremely low background radioactivity - unparalleled in space-borne MCP instruments. To meet this requirement without compromising detector gain and stability, PHOTONIS embarked on a major co-operation programme with Leicester University to develop a completely new MCP glass.
After several years of glass composition development, the final large-area plates were delivered in 1995 and are now installed in the Advanced Spectrometer awaiting launch July 1999. More information available from the Smithsonian Astrophysical Observatory and the Leicester University with a complete story on MCPs and their possible role in future experiments as X-ray optics (micropore optics, MPO) now in development by PHOTONIS under an ESA contract
Reference List
TECHNICAL REFERENCES
Select from the technical references available for Long-Life™ Microchannel Plates.
Technical Papers and Presentations
Technical Briefs
Technical References
Novel micropore x-ray optics produced with microchannel plate technology.
A new sub arcminute focussing device for x-rays photons above 10 keV
By M. Beijersbergen, M. Bavdaz , A. Peacokck, E. Tomaselli
Published in SPIE Procedings Vol. 4012, p 218-224 in 07/2000
High-resolution micropore x-ray optics produced with microchannel plate technology.
MCP based optics is a potential very light and compact X-ray detector
By M. Beijersbergen, M. Bavdaz , A. Peacokck, E. Tomaselli
Published in SPIE Procedings Vol. 4145, p 188-192 in 01/2001
Use of micropore x-ray optics produced with microchannel plate technology for the LOBSTER project.
See more details at http://www.src.le.ac.uk/projects/lobster/
Micro pore optics from planetary x-ray imager to industrial market, J. Mutz, R. Fairbend, J. Seguy, Photonis S.A.S. (France)
• Paper MPO WESTOPTICS (PDF)
• Talk WEST OPTICS MPO (PDF)
Reprinted from Nuclear Instruments and Methods, Vol. 162, 1979, pages 587 to 601: TP209 MCP Reprint.pdf
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