Unit for measuring absorbance

1. Unit for measurement of absorbance using a microchip, comprising:

a microchip with a continuous cavity, a sample chamber, a reagent chamber, a reagent mixing chamber and an absorbance measuring chamber for measuring absorbance of light by a sample which is arranged in a straight line in an area of the continuous cavity; and

a chip holder in which the microchip is located and which has a capillary part which is adapted and arranged for enabling light used for measuring absorbance to be delivered through the capillary part to the absorbance measuring chamber,

wherein the capillary part has a smaller opening diameter than a diameter of a cross section of the absorbance measuring chamber which is perpendicular to an optical axis of the absorbance measuring chamber, and

wherein an optical axis of the capillary part is aligned with the optical axis of the absorbance measuring chamber for measuring absorbance,

wherein the maximum length which is perpendicular to the optical axis of the capillary part D 1 , the length of the capillary part in the direction of the optical axis L 1 , the maximum length which is perpendicular to the optical axis of the absorbance measuring chamber D 2 and the distance between the end faces of the microchip which contain the absorbance measuring chamber and which runs in the direction of the optical axis of the absorbance measuring chamber L 2 have values which fulfill both of the following relationships:

D 1 <D 2 and D 1 /L 1 <( D 2 −D 1 )/2 L 2

wherein the capillary part has a middle area of increased diameter relative to inlet and outlet end areas of the capillary part.

2. Unit for measuring the absorbance in accordance with claim 1 , wherein the microchip comprises two plate components which are cemented together and between which a continuous cavity is located which runs along an end face of the plate components.

3. Unit for measuring the absorbance in accordance with claim 2 , wherein the cavity is made in an area of an adhesive surface between the plate components.

4. Unit for measuring the absorbance in accordance with claim 1 , wherein the inside of the capillary part has been subjected to antireflection processing.

5. Unit for measuring the absorbance in accordance with claim 1 , wherein the chip holder is made of aluminum and the inside of the capillary part has been subjected to black anodization processing.

6. Unit for measuring the absorbance in accordance with claim 1 , wherein the capillary part has a middle area of increased diameter relative to inlet and outlet end areas of the capillary part.

7. Unit for measuring the absorbance in accordance with claim 1 wherein the chip holder comprises two components which enclose the microchip, and wherein a groove is formed on the inside of at least one of the components which forms the capillary part.

8. Unit for measuring the absorbance in accordance with claim 1 wherein an elastic component is provided which presses the microchip against the chip holder.

9. Unit for measuring the absorbance in accordance with claim 1 wherein the inside of the capillary part has been subjected to antireflection processing.

10. Unit for measuring the absorbance in accordance with claim 1 wherein the chip holder is made of aluminum and the inside of the capillary part has been subjected to black anodization processing.

11. Unit for measuring the absorbance in accordance with claim 1 , wherein the chip holder comprises two components which enclose the microchip, and wherein a groove is formed on the inside of at least one of the components which forms the capillary part.

12. Unit for measuring the absorbance in accordance with claim 1 , wherein an elastic component is provided which presses the microchip against the chip holder.