Photo-optical method for determining fat content in meat

• US 3,877,818 A
• Filed: 01/28/1974
• Issued: 04/15/1975
• Est. Priority Date: 01/28/1974
• Status: Expired due to Term

• Current Assignee: George F. Button, Karl H. Norris
• Original Assignee: George F. Button, Karl H. Norris
• Inventors: Button, George F., Norris, Karl H.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Evans, F. L.
• Application Number:
  US05/437,094
• Time in Patent Office: 442 Days
• Field of Search: 356/51,74,186,188,189,201,204,209-212 250/338-341
• US Class Current: 356/416
• CPC Class Codes: A61B 5/4872 Body fat
• CPC Class Codes: G01J 3/12 Generating the spectrum; Monochromators
• CPC Class Codes: G01N 33/12 Meat; fish
• CPC Class Codes: Y10S 250/91 Food sample analysis using invisible radiant energy source

Abstract

Incandescent light exposes a meat sample to infra-red radiation which is transmitted through or reflected from the meat onto a tilting mirror which causes the respective transmitted or reflected light from the meat to pass through an interference filter at varying angles of incidence. By changing the angle of incidence of the filter, there is a change in the wavelength of radiation that passes through the filter over a narrow band width, in the infra-red spectrum. A filter is chosen for its sensitivity in the absorption band of meat fat. A detector receives light transmitted through the filter and generates an electrical signal that is processed to read out the fat content of the sample.

Claims

1. A method for measuring the fat content of a meat sample comprising the following steps:

illuminating a meat sample with radiation that is then reflected along a predetermined path;

systematically changing the wavelength of the reflected radiation over a wavelength band that corresponds to the radiation absorption band of meat fat, at an intermediate point along the path;

detecting a varying energy level of the reflected radiation as the wavelength is changed;

measuring the change in energy level divided by the average energy level as the wavelength changes; and

calibrating the measurement to correspond with the fat content in the sample.

2. A system for measuring fat content of a meat sample comprising:

means for illuminating the sample with radiation in a preselected frequency spectrum;

optical interference filter means for filtering the radiation reflected from the sample;

means communicating with the filter means for changing the angle of incidence of said reflected radiation impinging upon the filter means, which changes the wavelength of the radiation passing through the filter means, over a frequency band corresponding to the absorption band of meat fat;

detector means positioned behind the filter means for generating an electrical signal corresponding to the energy of the radiation in the fat absorption band, as reflected from the sample;

means responsive to the detector signal for computing changes in energy level as the radiation wavelength changes divided by the average energy level as the radiation wavelength changes; and

means connected to the output of the computing means for calibrating the output of the computing means as a function of fat content.

3. A photo-optical system for determining the fat content in a meat sample, the system comprising:

at least one light source positioned adjacent the sample for illuminating the sample and causing reflections therefrom;

lens means positioned adjacent the meat sample for collimating the reflections along a first light path;

mirror means interposed at a point along the first light path to divert the reflections along a second light path;

interference filter means interposed at a point along the second light path as that the diverted reflections are incident to the filter means;

drive means connected to the mirror which continually moves the mirror between two preselected limit positions for changing the angle of incidence of diverted reflections impinging upon the filter means thus changing the wavelength of light passing through the filter over a frequency band, corresponding to the absorption band of meat fat;

detector means positioned behind the filter means for detecting the energy associated with the reflections from the meat fat;

circuit means connected to the output of the detector means for measuring the change in the energy divided by the average energy, as the light wavelength changes; and

means connected to the circuit means for transposing the measurement to a value indicative of the fat content of the sample.

4. The subject matter of claim 3 wherein the light source comprises a plurality of symmetrically positioned lamps for evenly distributing incandescent light to the surface of the sample

5. The structure defined in claim 3 wherein the drive means comprises:

a pivot arm connected between a pivot point and the mirror; and

oscillating drive means for alternately swinging the pivot arm between the two limit positions.

6. The strucTure of claim 3 wherein the circuit means comprises:

divider means having a first input connected in circuit with the detector means and means for integrating the output from the detector means to produce a signal indicative of the average energy, a second input to the divider means connected to a circuit path comprising;

means for rectifying an AC component of the signal derived from the detector means output;

converting means connected to the rectifying means for integrating the rectified component to produce a corresponding DC signal; and

means connecting the converting means to the second input of the divider means for measuring the change in the energy divided by the average energy, as the light wavelength changes.

7. The subject matter set forth in claim 3 wherein the calibrating means comprises:

adjustable circuit means for producing a signal indicative of a predetermined measurement when a standard sample of known fat content is employed.

8. The circuitry defined in claim 3 together with a meter connected to the output of the calibrating means for providing a visual readout of the fat content.

9. The subject matter set forth in claim 3 wherein the circuit means comprises:

divider means having a first input connected in circuit with the detector means and means for integrating the output from the detector means to produce a signal indicative of the average energy, a second input to the divider connected to a circuit path comprising;

means for coupling an AC component of the detector output;

gain control means connected to the output of the coupling means for varying the gain of the AC component in response to the mirror means as the latter travels between the respective limit positions, the gain control means producing a half wave rectified AC signal out of phase with a regular AC signal having one half the peak voltage of the half wave rectified AC signal;

means connected to the output of the gain control means for adding the signals to form a full wave rectified signal having peaks of equal amplitude; and

means connected to the output of the adding means for integrating the full wave rectified signal and producing a DC level corresponding to the amplitude of the AC component.

10. The subject matter as set forth in claim 3 wherein the circuit means comprises:

a first function module having a first input for carrying the change in the energy ( Delta R), a second input of the module connected to a reference '"'"''"'"''"'"''"'"'A'"'"''"'"''"'"''"'"' for producing an output signal corresponding to Delta RA;

a second function module having a first input connected to the output signal from the first function module, a second input of the second module carrying the average energy (R), a third input to the second module connected to a reference B'"'"''"'"' for producing an output signal Delta RA.RB which is proportional to Delta RA/RB.

11. A method for measuring the fat content of a meat sample comprising the following steps:

illuminating a meat sample with radiation transmitted therethrough;

systematically changing the wavelength of the transmitted radiation over a wavelength band that corresponds to the radiation absorption band of meat fat, at an intermediate point along the path;

detecting a varying energy level of the transmitted radiation as the wavelength is changed;

measuring the change in energy level divided by the average energy level as the wavelength changes; and

calibrating the measurement to correspond with the fat content in the sample.

12. A system for measuring fat content of a meat sample comprising:

means for illuminating the sample with transmitted radiation in a preselected frequency spectrum;

optical interference filter means for filtering the radiation transmitted through the sample;

means communicating with the filter means for changing the angle of incidence of said transmitted radiation impinging upon the filter means, which changes the wavelength of the radIation passing through the filter means, over a frequency band corresponding to the absorption band of meat fat;

detector means positioned behind the filter means for generating an electrical signal corresponding to the energy of the radiation in the fat absorption band, as transmitted through the sample;

means responsive to the detector signal for computing changes in energy level as the radiation wavelength changes divided by the average energy level as the radiation wavelength changes; and

means connected to the output of the computing means for calibrating the output of the computing means as a function of fat content.

13. A photo-optical system for determining the fat content in a meat sample, the system comprising:

at least one light source positioned adjacent one side of the sample for illuminating the sample and causing light transmittance therethrough;

lens means positioned adjacent a second side of the meat sample for collimating the transmittance along a first light path;

mirror means interposed at a point along the first light path to divert the transmittance along a second light path;

interference filter means interposed at a point along the second light path so that the diverted transmittance is incident to the filter means;

drive means connected to the mirror which continually moves the mirror between two preselected limit positions for changing the angle of incidence of diverted transmittance impinging upon the filter means thus changing the wavelength of light passing through the filter over a frequency band, corresponding to the absorption band of meat fat;

detector means positioned behind the filter means for detecting the energy associated with the transmittance from the meat fat;

circuit means connected to the output of the detector means for measuring the change in the energy divided by the average energy, as the light wavelength changes; and

means connected to the circuit means for transposing the measurement to a value indicative of the fat content of the sample.

14. The subject matter of claim 13 wherein the light source comprises a plurality of symmetrically positioned lamps for evenly distributing incandescent light to the surface of the sample.

15. The structure defined in claim 13 wherein the drive means comprises:

a pivot arm connected between a pivot point and the mirror; and

oscillating drive means for alternately swinging the pivot arm between the two limit positions.

16. The structure claim 13 wherein the circuit means comprises:

divider means having a first input connected in circuit with the detector means and means for integrating the output from the detector means to produce a signal indicative of the average energy, a second input to the divider means connected to a circuit path comprising;

means for rectifying an AC component of the signal derived from the detector means output;

converting means connected to the rectifying means for integrating the rectified component to produce a corresponding DC signal; and

means connecting the converting means to the second input of the divider means for measuring the change in the energy divided by the average energy, as the light wavelength changes.

17. The subject matter set forth in clain 13 wherein the calibrating means comprises:

adjustable circuit means for producing a signal indicative of a predetermined measurement when a standard sample of known fat content is employed.

18. The circuitry defined in claim 13 together with a meter connected to the output of the calibrating means for providing a visual readout of the fat content.

19. The subject matter set forth in claim 13 wherein the circuit means comprises:

divider means having a first input connected in circuit with the detector means and means for integrating the output from the detector means to produce a signal indicative of the average energy, a second input to the divider connected to a circuit path comprising;

means for coupling an AC component of the detector output;

gain control means connected to the output of the coupling means for varying the gain of the AC component in response to the mirror means as the later travels between the respective limit positions, the gain control means producing a half wave rectified AC signal out of phase with a regular AC signal having one half the peak voltage of the half wave rectified AC signal;

means connected to the output of the gain control means for adding the signals to form a full wave rectified signal having peaks of equal amplitude; and

means connected to the output of the adding means for integrating the full wave rectified signal and producing a DC component.

20. The subject matter as set forth in claim 13 wherein the circuit means comprises:

a first function module having a first input for carrying the change in the energy ( Alpha T), a second input of the module connected to a reference '"'"''"'"''"'"''"'"'A'"'"''"'"''"'"''"'"' for producing an output signal corresponding to ( Delta TA);

a second function module having a first input connected to the output signal from the first function module, a second input of the second module carrying the average energy (T), a third input to the second module connected to a reference B'"'"''"'"' for producing an output signal Delta T - TB which is proportional to Delta TA/TB.