Changeable means for different total tracks and its method

1. An apparatus comprising:

at least one rotational reflection element capable of rotatably moving and comprising one or more reflection surface sets, wherein said reflection surface set comprises at least one reflection surface,

a fixing apparatus connected to said rotational reflection element so as to adjust and fix a position of the at least one rotational reflection element; and

wherein said fixing apparatus comprises:

one rotational base fixed on said rotational reflection element such that said rotational reflection element is capable of being circulated by adjusting said rotational base; and

a fixing pin capable of going through said rotational base to fix a position of said rotational reflection element.

2. The apparatus of claim 1 , wherein said rotational base comprises a scale for showing rotational positions of said rotational base.

3. The apparatus of claim 1 , wherein said fixing pin comprises a screw.

4. A method comprising:

determining a desired effective optical path length; and

circulating a rotational reflective element such that a certain reflection surface set is positioned along an optical path, wherein said rotational reflective element comprises a plurality of reflection surface sets, and each reflection surface set having at least one reflection surface; wherein said reflection surface sets are formed such that at least two of said reflection surface sets have different effective optical path lengths.

5. The method of claim 4 , wherein said rotational reflection element includes a fixing apparatus capable of adjusting and fixing a rotational position of said rotational reflection element.

6. The method of claim 4 , wherein said plurality of reflection surface sets are such that a direction and position of reflected light are substantially the same as a direction and position of incident light.

7. The method of claim 4 , wherein said rotational reflection element is a single element.

8. The method of claim 4 , wherein the reflection surface of the reflection surface set is formed by a reflection materials on a surface lying in a plane formed at a predetermined angle from a surface of said rotational reflection element.

9. The method of claim 4 , wherein the reflection surface set comprises a plurality of reflective glass surfaces.

10. A method comprising:

calculating a predetermined optical path based on one or more dimensions of a light-guide;

circulating a rotational reflection element to a reflection surface set such that said reflection surface set is positioned on a reflection path of said light-guide, wherein said rotational reflective element comprises a plurality of reflection surface sets, and each reflection surface set comprises at least one reflection surface; wherein said plurality of reflection surface sets are formed such that at least two of said reflection surface sets have different effective optical path lengths.

11. A method comprising:

circulating at least one rotational reflection element such that one of one or more reflection surface sets is positioned alone an optical path of a scanner;

wherein said circulating comprises rotating a fixing element coupled to said rotational reflection element; and

wherein said fixing element comprises a power source and a fixing pin, wherein said fixing pin is operable to fix a position of said rotational reflection element.

12. The method of claim 11 , wherein said power source comprises a motor.

13. The method of claim 12 , wherein said fixing element further comprises a transmission.