Biological optical measuring instrument

• US 20040236195A1
• Filed: 06/22/2004
• Published: 11/25/2004
• Est. Priority Date: 07/19/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Medical Corporation (Hitachi, Ltd.)
• Inventors: Kawaguchi, Tsuneaki, Furuzono, Eiji, Onozuka, Satoshi, Kaga, Mikihiro
• Granted Patent: US 7,460,894 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

A biomedical optical measurement apparatus comprising a light source unit for generating an inspection light containing multiple lights modulated at different frequencies, a light-receiving unit for receiving the light generated at said light source unit and passing through an object to be examined and for outputting the electric signals with the intensity corresponding to the received inspection light, and a detection means for detecting a signal with the same frequency of the reference signal in the output from said light-receiving unit. The detection means comprises an analog-digital conversion means for outputting digitized data by converting an input signal to a digital signal, a storage means for storing digitized data of multiple reference signals, a digital multiplication means for multiplying digitized data of input signals outputted from the analog-digital converting means by the digitized data of the reference signals read out from the storage means and for outputting the product of multiplication, and a digital band-limitation means for taking out DC data from the output from the digital multiplication means. Reference signal generating circuits of a number equal to that of frequencies of detected signals, which has been necessary for the conventional instrument, can be replaced by a single memory means and the configuration of the instrument can be simplified. Changes in frequency can be easily coped with by only re-writing the data of the storing means.

Claims

1. A biomedical optical measurement apparatus comprising;

a light source means for generating an inspection light containing multiple lights modulated at different frequencies,

a light-receiving means for receiving the light generated at said light source means and passing through an object to be examined and for outputting the electric signals with the intensity corresponding to the received inspection light, and

a detection means for detecting a signal with the same frequency of the reference signal in the output from said light-receiving unit, wherein

said detection means comprises;

an analog-digital conversion means for outputting digitized data by converting an input signal to a digital signal,

a storage means for storing digitized data of multiple reference signals,

a digital multiplication means for multiplying digitized data of input signals outputted from said analog-digital converting means by the digitized data of the reference signals read out from said storage means and for outputting the product of multiplication, and

a digital band-limitation means for taking out DC data from the output from said digital multiplication means.

2. The biomedical optical measurement apparatus of claim 1, wherein said digital multiplication means and said digital band limitation means are composed by a digital signal processor.

3. The biomedical optical measurement apparatus of claim 1 or claim 2, which instrument further comprises a delaying means for delaying digitized data of said reference signals.

4. The biomedical optical measurement apparatus of any one of claims 1-3, which instrument further comprises a function generating means for inputting the digitized data of said reference signal and for generating a function that becomes “

0”

or “

close to 0”

near the level changing point of the digitized data.

5. The biomedical optical measurement apparatus of any one of claims 1-4, wherein a digital signal processor including said digital multiplying means and said digital band-limitation means is provided for each modulation frequency.

6. The biomedical optical measurement apparatus of claim 5, wherein the digital signal processor comprises;

an analog-digital conversion means for outputting digitized data by converting an input signal to a digital signal,

a first digital multiplication means for multiplying digitized data of input signals outputted from said analog-digital converting means by the digitized data of the reference signals read out from said storage means and for outputting the product of multiplication,

a second digital multiplication means for multiplying the output from said the first digital multiplication means by low-pass filter coefficient and for outputting the product of multiplication, and

a digital band-limitation means for taking out DC data from the output from said second digital multiplication means.

7. The biomedical optical measurement apparatus of any one of claims 1-6, wherein said digital band-limitation means has a attenuation-band frequency fa satisfying fp≧

2fa when a frequency interval (pitch) of signals to be detected is fp.

10. The biomedical optical measurement apparatus of any one of claims 1-7, which instrument further comprises a control means for controlling said light source means, said light receiving means and said detection means, wherein said control means generates timing signals with a predetermined interval and controls irradiation of the inspection light from the light source means and signal detection by the detection means in a time-sharing manner according to the timing signal.

11. The biomedical optical measurement apparatus of any one of claims 1-7, which instrument further comprises a detection means comprising an amplifier for outputting multiple signals sequentially outputted from said light receiving means as a continuous signal and an analog-digital conversion means for converting the output from the amplifier, as said detection means, and a control means for controlling the detection means, wherein the sampling timing at the analog-digital conversion means is controlled by the timing signal outputted from said control means controls.

12. The biomedical optical measurement apparatus of any one of claims 1-7, which instrument further comprises, as said detection means, a detecting means comprising;

an analog-digital converting means for performing analog-digital conversion and outputting digitized data of the input signals,

a clock means for generating timing signals for said analog-digital converting means to perform analog-digital conversion at a specified sampling timing,

a function generating means for generating a function which becomes “

0”

or “

close to 0”

near the sampling time of said input signals and

a digital multiplying means for multiplying digitized data of input signals output from said analog-digital conversion means by the function from said function generating means, and outputting the product of the multiplication.

13. The biomedical optical measurement apparatus of claim 12, which instrument further comprises an integrating means for adding the output from said digital multiplying means posterior the digital multiplying means.

8. A biomedical optical measurement apparatus comprising;

a light source means for generating multiple inspection lights in a time-sharing manner,

a light-receiving means for sequentially receiving the inspection light generated at said light source unit and passing through an object to be examined, and

a detection means for detecting signals from said light-receiving means and for outputting them as signals for each of the said multiple inspection lights;

wherein

said detection means further comprises;

an analog-digital conversion means for converting analog input signals to digital signals and for outputting digitized data of the input signals,

a clock means for generating a timing signal so that said analog-digital converting means can begin analog-digital conversion at a specified sampling timing,

a function generating means for generating functions which become “

0”

or “

close to 0”

near the sampling time of said input signals,

a digital multiplying means for multiplying digitized data of input signals outputted from said analog-digital converting means by the function of said function generating means and for outputting the product of multiplication.

9. The biomedical optical measurement apparatus of claim 8, which instrument further comprises an integrating means for adding the output from said digital multiplication means posterior the digital multiplication means.

14. A detection circuit for a biomedical optical measurement apparatus comprising;

an analog-digital converting means for performing analog-digital conversion of input signals and for outputting digitized data of the input signal,

a function generator for generating one or more functions to be selected from trigonometric function, Gaussian function, Hamming and Hanning window functions,

a multiplying means for multiplying output from said analog-digital converting means by the function generated from said function generator.

15. The detection circuit of claim 14, which circuit further comprising, posterior said multiplying means, adding means for feeding back the sum (results of addition) from itself and adding to the output from said multiplying means.