Apparatus and method for biological observation using sound waves and light

1. A biological observation apparatus comprising:

a sound wave radiating unit configured to radiate an ultrasound wave into an object to be examined, the object located in living tissue, wherein the sound wave radiating unit radiates the ultrasound wave as a cyclic compressional wave while successively changing a frequency of the ultrasound wave to increase the density of a portion of the object to be examined in the living tissue;

a light radiating unit configured to radiate light into the object;

a light interfering unit configured to generate interference light by causing the light radiated from the light radiating unit to interfere with light reflected from the portion of the object with the increased density, and further configured to radiate said interference light;

a light detector configured to detect the interference light radiated from the light interfering unit and outputs an interference signal corresponding to the interference light;

a memory unit configured to store interference signals; and

a calculator configured to calculate an amount of frequency modulation of the radiated light based on the interference signals, which are outputted from the light detector and correspond to individual timings sequentially outputted from the memory unit, and sequentially calculates a difference value between the amounts of frequency modulation of two observed areas that are adjacent to each other in a depth direction in the living tissue, wherein the calculator is further configured to relate the difference value to a position with respect to the living tissue, stores the difference value and the position, and generates a tomographic image of the object based on the difference value and the position.

2. The apparatus according to claim 1 , wherein the calculation unit is further configured to store a first amount of frequency modulation calculated at a first timing and calculates the difference value between the first amount of frequency modulation and a second amount of frequency modulation calculated at a second timing.

3. The apparatus according to claim 2 , wherein the calculation unit is further configured to overwrite the stored a first amount of frequency modulation with the second amount of frequency modulation and sets the second timing to current first timing.

4. The apparatus according to claim 1 , wherein the calculation unit is further configured to store the calculated amounts of frequency modulation.

5. The apparatus according to claim 1 , further comprising a sound wave converging unit configured to radiate the ultrasound wave into the object while making the ultrasound wave converge.

6. The apparatus according to claim 1 , further comprising a scan unit configured to change a position of the sound wave radiating unit and the light radiating unit with respect to the living tissue.

7. The apparatus according to claim 1 , wherein the calculation unit is further configured to produce image data of the living tissue based on the difference value and the position with respect to the living tissue.

8. The apparatus according to claim 7 , further comprising a display unit configured to display an image of the living tissue based on the image data.

9. The apparatus according to claim 1 , wherein the sound wave radiating unit is positionable so that the ultrasound wave and the light are radiated in the same depth direction in the living tissue.

10. A biological observation method comprising:

radiating an ultrasound wave into an object to be examined, the object located in living tissue, wherein the ultrasound wave is radiated as a cyclic compressional wave while successively changing a frequency thereof to increase the density of a portion of the object to be examined in the living tissue;

radiating light into the object;

generating interference light by causing the light radiated from the light radiating unit to interfere with light reflected from the portion of the object with the increased density, and further radiating said interference light;

detecting the radiated interference light;

outputting an interference signal corresponding to the interference light;

calculating the amounts of frequency modulation of the radiated light based on the outputted interference signals, which correspond to individual timings sequentially outputted from the memory unit;

sequentially calculating a difference value between the amounts of frequency modulation of two observed areas that are adjacent to each other in a depth direction in the living tissue;

relating the difference value to a position with respect to the living tissue;

storing the difference value and the position; and

generating a tomographic image of the object based on the difference value and the position.

11. The method according to claim 10 , wherein the ultrasound wave is radiated as a converging wave into the object.

12. The method according to claim 10 , wherein the ultrasound wave and light are radiated in the same depth direction in the living tissue.