Pulse width modulation of continuum sources for determination of chemical composition

• US 9,778,172 B2
• Filed: 12/20/2016
• Issued: 10/03/2017
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Pelletier, Michael, Soltmann, William, Perkins, David L., Jones, Christopher M.
• Primary Examiner(s): NGUYEN, SANG H
• Application Number:
  US15/385,482
• Publication Number:
  US 20170102320A1
• Time in Patent Office: 287 Days
• Field of Search: 356432-444, 2502691, 25027711, 250214 DC, 2502082, 250504 R
• CPC Class Codes: E21B 47/113 using electrical indications; using light radiations
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/027 Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/108 for measurement in the infrared range
• CPC Class Codes: G01J 3/427 Dual wavelengths spectrometry
• CPC Class Codes: G01J 3/433 Modulation spectrometry; Derivative spectrometry
• CPC Class Codes: G01J 5/53 Reference sources, e.g. standard lamps; Black bodies
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/47 Scattering, i.e. diffuse reflection G01N21/25, G01N21/41 take precedence G01N21/55 takes precedence
• CPC Class Codes: G01N 2201/061 Sources
• CPC Class Codes: G01N 2201/06186 Resistance heated; wire sources; lamelle sources
• CPC Class Codes: G01N 2201/0696 Pulsed
• CPC Class Codes: G01N 2201/12 Circuits of general importance; Signal processing
• CPC Class Codes: G01V 8/10 Detecting, e.g. by using light barriers by reflection from the object G01S17/00
• CPC Class Codes: H03K 7/08 Duration or width modulation ; Duty cycle modulation
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: Y02B 20/40 : Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A light source and a method for its use in an optical sensor are provided, the light source including a resistively heated element. The light source includes a power circuit configured to provide a pulse width modulated voltage to the resistively heated element, the pulse width modulated voltage including: a duty cycle with a first voltage; and a pulse period including a period with a second voltage, wherein: the duty cycle, the first voltage, and the pulse period are selected so that the resistively heated element is heated to a first temperature; and the first temperature is selected to emit black body radiation in a continuum spectral range. Also provided is an optical sensor for determining a chemical composition including a light source as above.

Claims

1. A light source for use in an optical sensor, the light source comprising:

a resistively heated element which produces an illumination light;

an optical modulator that modulates at least a first portion of the illumination light; and

a power circuit configured to provide a pulse width modulated voltage to the resistively heated element, the pulse width modulated voltage comprising;

a duty cycle with a first voltage; and

a pulse period including a period with a second voltage, wherein;

the duty cycle, the first voltage, and the pulse period are selected so that the resistively heated element is heated to a first temperature; and

the first temperature is selected to emit black body radiation in a continuum spectral range.

2. The light source of claim 1 wherein the second voltage is lower than the first voltage.

3. The light source of claim 1 wherein the second voltage is zero.

4. The light source of any one of claim 1, 2, or 3 wherein the duty cycle, the second voltage, and the pulse period are selected so that the resistively heated element is heated to a second temperature lower than the first temperature.

5. The light source of claim 4 wherein the second temperature is selected to emit black body radiation in a second continuum spectral range.

6. The light source of claim 1 wherein the illumination light passes through a beam splitter, wherein the splitter splits the illumination light into the first portion and a second portion, and wherein the second portion is output as a reference signal.

7. The light source of claim 6 wherein the second portion is reflected by a mirror prior to being output as the reference signal.

8. The light source of claim 1, further comprising an optical delivery system that collects radiation emitted by the heated element and forms a collimated beam that is the illumination light.