# US 9,520,260 B2 · Photo emitter X-ray source array (PeXSA)

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- Number: US 9,520,260 B2
- Document ID: US9520260B2
- Status: Granted
- Kind: B2
- Application number: 14/026,697
- Filed: 2013-09-13
- Published: 2014-03-20
- Granted: 2016-12-13
- Earliest claimed: 2012-09-14
- Assignees: The Board of Trustees of the Leland Stanford Junior University
- Applicants: The Board of Trustees of the Leland Stanford Junior University
- Inventors: Lambertus Hesselink; R. Fabian W. Pease; Piero Pianetta; Juan R. Maldonado; Yao-Te Cheng; Jason Ryan
- Web page: https://patentgrep.com/patent/US9520260B2

## CPC

- H01J 35/02: Details
- H01J 35/065: {Field emission, photo emission or secondary emission cathodes}
- H01J 35/066: {Details of electron optical components, e.g. cathode cups}
- H01J 35/147: {Spot size control}
- H01J 35/116: {Transmissive anodes (acting as a window H01J35/186)}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A photo-emitter x-ray source is provided that includes a photocathode electron source, a laser light source, where the laser light source illuminates the photocathode electron source to emit electrons, and an X-ray target, where the emitted electrons are focused on the X-ray target, where the X-ray target emits X-rays. The photocathode electron source can include alkali halides (such as CsBr and CsI), semiconductors (such as GaAs, InP), and theses materials modified with rare Earth element (such as Eu) doping, electron beam bombardment, and X-ray irradiation, and has a form factor that includes planar, patterned, or optically patterned. The X-ray target includes a material such as tungsten, copper, rhodium or molybdenum. The laser light source is pulsed or configured by light modulators including acousto-optics, mode-locking, micro-mirror array, and liquid crystals, the photocathode electron source includes a nano-aperture or nano-particle arrays, where the nano-aperture is a C-aperture or a circular aperture.

## Claims

### Claim 1

A photo-emitter x-ray source, comprising:
a. a photocathode electron source;
b. a laser light source;
c. a beam forming device comprising a spatial light modulator;
d. electron optics; and
e. an X-ray target, wherein said laser light source outputs a beam directed to said spatial light modulator, wherein said spatial light modulator forms said beam into an optical spatially patterned beam, wherein said optical spatially patterned beam illuminates said photocathode electron source, wherein said photocathode electron source emits electrons having an electron pattern according to said spatial light modulator, wherein said electron optics comprises an electric field, a magnetic field, or said electric field and said magnetic field disposed to image said electron pattern onto said X-ray target, wherein said X-ray target emits a pattern of X-rays, wherein said pattern of X-rays comprise a patterned partially-coherent X-ray beam.

### Claim 2 (depends on 1)

The photo-emitter x-ray source of claim 1, wherein said photocathode electron source comprises a material selected from the group consisting of alkali halides, GaAs, InP, rare Earth element doped alkali halides, rare Earth element doped GaAs, rare Earth element doped InP, alkali halides modified by electron beam bombardment, GaAs modified by electron beam bombardment, InP modified by electron beam bombardment, alkali halides modified by X-ray irradiation, GaAs modified by X-ray irradiation, and InP modified by X-ray irradiation.

### Claim 3 (depends on 1)

The photo-emitter x-ray source of claim 1, wherein said photocathode electron source comprises a material capable of operating at energies below a bandgap of said material through doped states or color centers created by UV irradiations, X-rays irradiations, gamma rays irradiations or electron bombardment.

### Claim 4 (depends on 1)

The photo-emitter x-ray source of claim 1, wherein said emitted pattern of X-rays comprise energies below 250 KeV.

### Claim 5 (depends on 1)

The photo-emitter x-ray source of claim 1, wherein said electron optics are configured to focus the electrons emitted from the photocathode electron source to a spot size in a range between 20 nm to 5 mm.

### Claim 6 (depends on 1)

The photo-emitter x-ray source of claim 1, wherein said laser light source emitting a radiation at a wavelength in a range of 200 nm to 800 nm.

### Claim 7 (depends on 1)

The photo-emitter x-ray source of claim 1, wherein said beam forming device comprises a nano-aperture disposed directly on said photocathode electron source, wherein said nano-aperture comprises one of nano-particle arrays, a C-aperture, or a circular aperture.

### Claim 8 (depends on 1)

The photo-emitter X-ray source of claim 1, wherein said X-ray target comprises a material selected from the group consisting of tungsten, copper, rhodium and molybdenum.

### Claim 9 (depends on 1)

The photo-emitter X-ray source of claim 1, wherein said photocathode electron source comprises a form factor selected from the group consisting of planar, patterned, and optically patterned.

### Claim 10 (depends on 1)

The photo-emitter X-ray source of claim 1, wherein said laser light source is temporally modulated.