Endoscope and endoscopic system

1. A camera head which is utilized in a medical instrument comprising:

a four-color separation prism comprising a first color separation prism, a second color separation prism, a third color separation prism and a fourth color separation prism, the first color separation prism including a light incident surface, the third color separation prism including a light incident surface which, in operation, reflects a third component of the light from an object, the light incident surface of the third color separation prism being adjacent a light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism arranged relative to the light incident surface of the first color separation prism such that a first angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism, in operation, reflects a second component of the light from an object, the third color separation prism including a light reflective surface arranged relative to the light incident surface of the first color separation prism such that a second angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the third color separation prism, the first angle being less than the second angle,

wherein the light incident surface of the third color separation prism is coextensive with the light reflective surface of the second color separation prism, and the light incident surface of the second color separation prism is adjacent a light reflective surface of the first color separation prism,

wherein one of the first color separation prism, the second color separation prism, the third color separation prism and the fourth color separation prism is an infrared prism.

2. The camera head of claim 1 , wherein the infrared prism is closest to a distal end of the endoscope.

3. The camera head of claim 1 , wherein the light reflective surface of the first color separation prism is arranged relative to the light incident surface of the first color separation prism such that a third angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the first color separation prism, the first angle being less than the third angle.

4. A camera head which is utilized in a medical instrument comprising:

a four-color separation prism comprising a first color separation prism, a second color separation prism, a third color separation prism and a fourth color separation prism, the first color separation prism including a light incident surface, the third color separation prism including a light incident surface which, in operation, reflects a third component of the light from an object, the light incident surface of the third color separation prism being adjacent a light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism arranged relative to the light incident surface of the first color separation prism such that a first angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism, in operation, reflects a second component of the light from an object, the third color separation prism including a light reflective surface arranged relative to the light incident surface of the first color separation prism such that a second angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the third color separation prism, the first angle being less than the second angle,

wherein the light incident surface of the third color separation prism is coextensive with the light reflective surface of the second color separation prism, and the light incident surface of the second color separation prism is adjacent a light reflective surface of the first color separation prism,

wherein one of the first color separation prism, the second color separation prism, the third color separation prism and the fourth color separation prism is an infrared prism,

wherein the light reflective surface of the second color separation prism, in operation, reflects a fourth component of the light from an object.

5. The camera head of claim 4 , wherein the light reflective surface of the first color separation prism is arranged relative to the light incident surface of the first color separation prism such that a third angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the first color separation prism, the first angle being less than the third angle.

6. A camera head which is utilized in a medical instrument comprising:

a four-color separation prism comprising a first color separation prism, a second color separation prism, a third color separation prism and a fourth color separation prism, the first color separation prism including a light incident surface, the third color separation prism including a light incident surface which, in operation, reflects a third component of the light from an object, the light incident surface of the third color separation prism being adjacent a light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism arranged relative to the light incident surface of the first color separation prism such that a first angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism, in operation, reflects a second component of the light from an object, the third color separation prism including a light reflective surface arranged relative to the light incident surface of the first color separation prism such that a second angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the third color separation prism, the first angle being less than the second angle,

four image sensors included in each prism, and

a signal output circuit that outputs an RGB signal and an IR signal of an image captured by each image sensor,

wherein the light incident surface of the third color separation prism is coextensive with the light reflective surface of the second color separation prism, and the light incident surface of the second color separation prism is adjacent a light reflective surface of the first color separation prism,

wherein one of the first color separation prism, the second color separation prism, the third color separation prism and the fourth color separation prism is an infrared prism.

7. The camera head of claim 6 , wherein a signal cable for transferring an image signal is mounted in the camera head.

8. A medical camera system comprising:

a camera head configured to include a four-color separation prism comprising a first color separation prism, a second color separation prism, a third color separation prism and a fourth color separation prism, the first color separation prism including a light incident surface, the third color separation prism including a light incident surface which, in operation, reflects a third component of the light from an object, the light incident surface of the third color separation prism being adjacent a light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism arranged relative to the light incident surface of the first color separation prism such that a first angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism, in operation, reflects a second component of the light from an object, the third color separation prism including a light reflective surface arranged relative to the light incident surface of the first color separation prism such that a second angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the third color separation prism, the first angle being less than the second angle,

wherein the light incident surface of the third color separation prism is coextensive with the light reflective surface of the second color separation prism, and the light incident surface of the second color separation prism is adjacent a light reflective surface of the first color separation prism,

wherein one of the first color separation prism, the second color separation prism, the third color separation prism and the fourth color separation prism is an infrared prism,

a signal output unit that is connected to the camera head via a signal cable, and outputs the RGB signal and the IR signal from the camera head to a display unit.

9. The medical camera system of claim 8 , wherein the signal output unit outputs the image signal to the display unit in either of a dual output mode or a superimposed output mode.

10. The medical camera system of claim 9 , wherein in the dual output mode, the signal output unit outputs the RGB image and the IR image on separate screens of the display unit at the same time.

11. The medical camera system of claim 9 , wherein in the superimposed output mode, the signal output unit outputs a combined image in which the RGB image and the IR image are superimposed on each other.

12. A prism which is utilized in a medical instrument comprising:

a four-color separation prism comprising a first color separation prism, a second color separation prism, a third color separation prism and a fourth color separation prism, the first color separation prism including a light incident surface, the third color separation prism including a light incident surface which, in operation, reflects a third component of the light from an object, the light incident surface of the third color separation prism being adjacent a light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism arranged relative to the light incident surface of the first color separation prism such that a first angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the second color separation prism, the light reflective surface of the second color separation prism, in operation, reflects a second component of the light from an object, the third color separation prism including a light reflective surface arranged relative to the light incident surface of the first color separation prism such that a second angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the third color separation prism, the first angle being less than the second angle,

wherein the light incident surface of the third color separation prism is coextensive with the light reflective surface of the second color separation prism, and the light incident surface of the second color separation prism is adjacent a light reflective surface of the first color separation prism,

wherein one of the first color separation prism, the second color separation prism, the third color separation prism and the fourth color separation prism is an infrared prism.

13. The prism of claim 12 , wherein the light reflective surface of the first color separation prism is arranged relative to the light incident surface of the first color separation prism such that a third angle is formed between the light incident surface of the first color separation prism and the light reflective surface of the first color separation prism, the first angle being less than the third angle.

14. The prism of claim 12 , wherein the light reflective surface of the second color separation prism, in operation, reflects a fourth component of the light from an object.