Method and apparatus for determining the phase and/or amplitude information of an electromagnetic wave for photomixing

• US 7,053,357 B2
• Filed: 11/29/2004
• Issued: 05/30/2006
• Est. Priority Date: 09/05/1996
• Status: Expired due to Fees

• Current Assignee: Rudolf Schwarte
• Original Assignee: Rudolf Schwarte
• Inventors: Schwarte, Rudolf
• Primary Examiner(s): Le, Que T.
• Assistant Examiner(s): LU, TONY W
• Application Number:
  US10/999,582
• Publication Number:
  US 20050092897A1
• Time in Patent Office: 547 Days
• Field of Search: 250/214, 257/290
• US Class Current: 250/214.1
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4914 of detector arrays, e.g. charge-transfer gates
• CPC Class Codes: G01S 7/4915 Time delay measurement, e.g. operational details for pixel components signal extraction and conditioning G01S7/493; Phase measurement

Abstract

A method and corresponding device for determining the phase and/or amplitude data of an electromagnetic wave. The method comprises the steps: beaming an electromagnetic wave onto the surface of at least one pixel having at least two light sensitive modulation gates G_am, G_bm and associated accumulation gates G_a and G_b, applying modulation voltages U_am(t) and U_bm(t) to gates G_am and G_bm, applying a direct voltage to accumulation gates G_a and G_b, wherein the charge carriers produced in modulation gates G_am and G_bm by the incident electromagnetic wave being subjected to a potential gradient due to the modulation voltages U_am(t) and U_bm(t), thereby drifting to the corresponding accumulation gate G_a or G_b, and forwarding the charge carriers to evaluation electronics. A plurality of corresponding pixels can be assembled to form an array.

Claims

1. A method of determining the phase and/or amplitude information of an electromagnetic wave

in which an electromagnetic wave is radiated onto the surface of a photonic mixing element having at least one pixel, wherein the pixel has at least two light-sensitive modulation photogates G_am and G_bm and associated accumulation gates G_a and G_b,

in which there are applied to the modulation photogates G_am and G_bm modulation photogate voltages U_am(t) and U_bm(t) which are in the form of U_am(t)=U_o+U_m(t) and U_bm(t)=U_o−

U_m(t), wherein U_o represents a bias voltage of the accumulation gates G_a and G_b,

wherein applied to the accumulation gates G_a and G_b is a dc voltage whose magnitude is at least as great as the magnitude of the sum of U_o and the amplitude of the modulation voltage U_m(t),

in which charge carriers produced in a space charge zone of the modulation photogates G_am and G_bm by the electromagnetic wave are exposed to a potential gradient of a drift field in dependence on the polarity of the modulation photogate voltages U_am(t) and U_bm(t) and drift to the corresponding accumulation gate G_a and G_b,

in which charges q_a and q_b which have drifted to the respective accumulation gates G_a and G_b are taken off, and

wherein the phase and amplitude information is directly computed in an electronic pixel reading-out and signal pre-processing system which is integrated on a chip containing said photonic mixing element.

2. The method according to claim 1, characterized in that pixel phase is ascertained directly by an active pixel sensor structure (APS), wherein the pixel phase is then read out by way of a multiplex structure disposed on the chip.

3. The method according to claim 2, wherein the pixel phase is read out selectively by way of said multiplex structure.

4. The method according to claim 2, wherein the pixel phase is read out serially by way of said multiplex structure.

5. The method according to claim 1, characterized in that pixel transit time and pixel brightness are ascertained directly by an active pixel sensor structure (APS), wherein said pixel transit time and pixel brightness are then read out by way of a multiplex structure disposed on the chip.

6. The method according to claim 5, wherein the pixel transit time and the pixel brightness are read out selectively by way of said multiplex structure.

7. The method according to claim 5, wherein the pixel transit time and the pixel brightness are read out serially by way of said multiplex structure.

8. A method of determining the phase and/or amplitude information of an electromagnetic wave

in which an electromagnetic wave is radiated onto the surface of a photonic mixing element having a plurality of pixels, wherein each of the pixels has at least two light-sensitive modulation photogates G_am and G_bm and associated accumulation gates G_a and G_b,

in which there are applied to the modulation photogates G_am and G_bm modulation photogate voltages U_am(t) and U_bm(t) which are in the form of U_am(t)=U_o+U_m(t) and U_bm(t)=U_o−

U_m(t), wherein U_o represents a bias voltage of the accumulation gates G_a and G_b,

wherein applied to the accumulation gates G_a and G_b is a dc voltage whose magnitude is at least as great as the magnitude of the sum of U_o and the amplitude of the modulation voltage U_m(t),

in which charge carriers produced in a space charge zone of the modulation photogates G_am and G_bm by the electromagnetic wave are exposed to a potential gradient of a drift field in dependence on the polarity of the modulation photogate voltages U_am(t) and U_bm(t) and drift to the corresponding accumulation gate G_a and G_b,

in which charges q_a and q_b which have drifted to the respective accumulation gates G_a and G_b are taken off, wherein a plurality of the pixels are arranged as a 3D-line or matrix camera, which is combined with a conventional 2D-camera, and

wherein spectral allocation and feed of an active modulated illumination component to the 3D-camera and of other unmodulated illumination components is effected by a beam splitter.

9. The method according to claim 8, wherein at least three separate ones of the photonic mixing element are provided in a spaced relationship in order to determine an exact position of an object from which electromagnetic waves are received by said at least three photonic mixing elements, in a manner according to a global positioning system (GPS).

10. A photonic mixing element

with at least one pixel (1),

which has at least two light-sensitive modulation photogates (G_am, G_bm) comprising terminals for and adapted to receive modulation photogate voltages U_am(t) and U_bm(t) which are in the form of U_am(t)=U_o+U_m(t) and U_bm(t)=U_o−

U_m(t),

accumulation gates (G_a, G_b) which are associated with the modulation photogates (G_am, G_bm) and which are shaded relative to an incident electromagnetic wave, wherein U_o represents a bias voltage of the accumulation gates (G_a, G_b) and U_m(t) represents modulation voltage, and

wherein an electronic pixel reading-out and signal pre-processing system is associated with a chip containing said pixel.

11. The photonic mixing element according to claim 10, characterized in that the electronic pixel reading-out and signal pre-processing system is provided as an active pixel sensor (APS) structure, wherein a multiplex structure is disposed on the chip.

12. The photonic mixing element according to claim 11, wherein said multiplex structure selectively reads out the active pixel sensor (APS) structure.

13. The photonic mixing element according to claim 11, wherein said multiplex structure serially reads out the active pixel sensor (APS) structure.

14. A 3D-camera comprising an apparatus for determining phase information of an electromagnetic wave, the apparatus

having at least one photonic mixing element comprising:

at least one pixel (1),

which has at least two light-sensitive modulation photogates (G_am, G_bm) comprising terminals for and adapted to receive modulation photogate voltages U_am(t) and U_bm(t) which are in the form of U_am(t)=U_o+U_m(t) and U_bm(t)=U_o−

U_m(t),

accumulation gates (G_a, G_b) which are associated with the modulation photogates (G_am, G_bm) and which are shaded relative to an incident electromagnetic wave, wherein U_o represents a bias voltage of the accumulation gates G_a and G_b, and

having a modulation generator (10, 13), and

having a transmitter (4) that irradiates the electromagnetic wave which is intensity-modulated by the modulation generator (10, 13) in predetermined manner,

wherein the electromagnetic wave which is reflected by an object (6) is radiated onto the surface of the photonic mixing element, and

wherein the modulation generator (10, 13) supplies the photonic mixing element with modulation voltages U_m(t) which are in a predetermined phase relationship with respect to the phase of the electromagnetic wave that is irradiated from the transmitter.

15. The 3D-camera according to claim 14, wherein the 3D-camera is combined with a 2D-camera, the 2D-camera arranged to receive electromagnetic waves from the object (6) at about the same direction which the 3D-camera receives said electromagnetic wave which is reflected by the object (6), wherein a beam splitter is provided in order to feed an active modulated illumination component to the 3D-camera and a remaining unmodulated illumination component to the 2D-camera.

16. A method of determining the phase and/or amplitude information of an electromagnetic wave

in which an electromagnetic wave is radiated onto the surface of a photonic mixing element having at least one pixel, wherein the pixel has at least two light-sensitive modulation photogates G_am and G_bm and associated accumulation gates G_a and G_b,

in which there are applied to the modulation photogates G_am and G_bm modulation photogate voltages U_am(t) and U_bm(t) which are in the form of U_am(t)=U_o+U_m(t) and U_bm(t)=U_o−

U_m(t), wherein U_o represents a bias voltage of the accumulation gates G_a and G_b,

wherein applied to the accumulation gates G_a and G_b is a dc voltage whose magnitude is at least as great as the magnitude of the sum of U_o and the amplitude of the modulation voltage U_m(t),

in which charge carriers produced in a space charge zone of the modulation photogates G_am and G_bm by the electromagnetic wave are exposed to a potential gradient of a drift field in dependence on the polarity of the modulation photogate voltages U_am(t) and U_bm(t) and drift to the corresponding accumulation gate G_a and G_b,

in which charges q_a and q_b which have drifted to the respective accumulation gates G_a and G_b are taken off, and

wherein illumination of a scene is provided with modulated light from different spectral regions in order to obtain different color components of a resulting image for reconstructing a complete color image together with spatial depth information.