Produce data collector with enhanced LVF spectrometer

• US 6,505,775 B1
• Filed: 04/25/2000
• Issued: 01/14/2003
• Est. Priority Date: 04/25/2000
• Status: Expired due to Term

• Current Assignee: NCR Voyix Corporation
• Original Assignee: NCR Corporation
• Inventors: Gu, Yeming, Tang, Hong, Collins, Jr., Donald A., Aleshire, Rex A.
• Primary Examiner(s): St. Cyr, Daniel
• Application Number:
  US09/558,013
• Time in Patent Office: 994 Days
• Field of Search: 235/454, 235/455, 235/462.01, 235/462.25, 235/462.41, 235/462.11, 235/462.14
• US Class Current: 235/454
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/0262 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters

Abstract

A produce data collector which includes a spectrometer which minimizes noise from scattered light and from wavelengths outside the operating range of the spectrometer. The produce data collector includes a light source for illuminating a produce item. The spectrometer obtains spectral information about the produce item in incoming reflected light from the produce item and includes a linear variable filter, a photodetector adjacent the linear variable filter, and an optical slit member above a primary surface of the linear variable filter which has a slit with a width sufficient to minimize scattering of the incoming light by interior surfaces of the linear variable filter. The produce data collector may additionally include a filter, such as an infrared filter.

Claims

1. A spectrometer comprising:

a linear variable filter which includes a primary surface and a number of interior surfaces, and which splits filtered incoming light reaching the primary surface into a number of light portions having different wavelengths;

a photodetector adjacent the linear variable filter which samples the light portions and produces electrical signals containing information about each light portion;

an optical slit member above the primary surface of the linear variable filter which has a slit with a width sufficient to minimize scattering of the incoming light by the interior surfaces of the linear variable filter; and

a filter above the optical slit member which filters light within incoming light which is outside a wavelength range of operation of the linear variable filter to produce the filtered incoming light.

2. The spectrometer as recited in claim 1, further comprising:

a housing having interior walls adjacent the linear variable filter;

wherein the optical slit member also minimizes scattering of the incoming light by the interior walls of the housing.

3. The spectrometer as recited in claim 1, wherein the filter above the optical slit member comprises:

an infrared filter which minimizes infrared light within the incoming light.

4. The spectrometer as recited in claim 1, further comprising:

control circuitry which produces digital signals from the electrical signals.

5. The spectrometer as recited in claim 1, further comprising:

a light source for illuminating an object to obtain spectral information about the object in incoming reflected light from the object.

6. The spectrometer as recited in claim 5, wherein the light source is a substantially white light source.

7. A produce data collector comprising:

a light source for illuminating a produce item;

a spectrometer to obtain spectral information about the produce item in incoming reflected light from the produce item including

a linear variable filter which includes a primary surface and a number of interior surfaces, and which splits filtered incoming light reaching the primary surface into a number of light portions having different wavelengths;

a photodetector adjacent the linear variable filter which samples the light portions and produces electrical signals containing information about each light portion;

an optical slit member above the primary surface of the linear variable filter which has a slit with a width sufficient to minimize scattering of the incoming light by the interior surfaces of the linear variable filter; and

a filter above the optical slit member which filters light within the incoming reflected light which is outside a wavelength range of operation of the linear variable filter to produce the filtered incoming light; and

control circuitry which produces digital signals from the electrical signals.

8. A produce recognition system comprising:

a produce data collector including

a light source for illuminating a produce item;

a linear variable filter which includes a primary surface and a number of interior surfaces, and which splits filtered incoming reflected light from the produce item reaching the primary surface into a number of light portions having different wavelengths;

a photodetector adjacent the linear variable filter which samples the light portions and produces electrical signals containing information about each light portion;

an optical slit member above the primary surface of the linear variable filter which has a slit with a width sufficient to minimize scattering of the incoming light by the interior surfaces of the linear variable filter; and

a filter above the optical slit member which filters light within incoming light which is outside a wavelength range of operation of the linear variable filter to produce the filtered incoming reflected light; and

control circuitry which produces digital spectral information about the produce item from the electrical signals; and

a computer which compares the digital spectral information to reference spectra to identify the produce item.

9. A method of capturing spectral information about an item comprising the steps of:

(a) filtering light within incoming light reflected from the item which is outside a wavelength range of operation of a linear variable filter;

(b) receiving filtered incoming light through a primary surface of the linear variable filter;

(c) minimizing scattering of the incoming light by interior surfaces of the linear variable filter by an optical slit member above the primary surface;

(d) splitting incoming light into a number of light portions having different wavelengths by the linear variable filter; and

(e) sampling the light portions by a photodetector to produce electrical signals containing information about each light portion.

10. A method of capturing spectral information about an item comprising the steps of:

(a) filtering light within incoming light reflected from the item which is outside a wavelength range of operation of a linear variable filter;

(b) receiving filtered incoming light through a primary surface of the linear variable filter;

(c) minimizing scattering of the incoming light by interior surfaces of the linear variable filter and a housing containing the linear variable filter by an optical slit member above the primary surface;

(d) splitting incoming light into a number of light portions having different wavelengths by the linear variable filter; and

(e) sampling the light portions by a photodetector to produce electrical signals containing information about each light portion.

11. The method as recited in claim 10, wherein step

(a) comprises the substep of:

(a-1) filtering infrared light.

12. The method as recited in claim 10, wherein the item comprises a produce item.

13. A method of capturing spectral information about a produce item comprising the steps of:

(a) illuminating the produce item;

(b) filtering incoming light reflected from the produce item;

(c) receiving filtered incoming light through a primary surface of a linear variable filter;

(d) minimizing scattering of the filtered incoming light by interior surfaces of the linear variable filter and a housing containing the linear variable filter by an optical slit member above the primary surface;

(e) splitting the filtered incoming light into a number of light portions having different wavelengths by the. linear variable filter; and

(f) sampling the light portions by a photodetector to produce electrical signals containing information about each light portion.

14. A method of identifying a produce item comprising the steps of:

(a) illuminating the produce item;

(b) filtering incoming light reflected from the produce item;

(c) receiving filtered incoming light through a primary surface of a linear variable filter;

(d) minimizing scattering of the filtered incoming light by interior surfaces of the linear variable filter and a housing containing the linear variable filter by an optical slit member above the primary surface;

(e) splitting the filtered incoming light into a number of light portions having different wavelengths by the linear variable filter;

(f) sampling the light portions by a photodetector to produce electrical signals containing information about each light portion;

(g) digitizing the electrical signals to produce a digital spectrum for the produce item; and

(h) comparing the digital spectrum to reference spectra to identify the produce item.