Light measurement apparatus

1. A light measurement apparatus, for a light source on a hand-held dental light curing unit to which a light guide apparatus is connected, with the light guide apparatus having a light outlet area, and the light measurement apparatus being on a base unit having a light sensor arrangement ( 36 ) having at least two sensors ( 40 a , 40 b , 40 c , . . .), to which light from the light outlet area ( 30 ) can be applied wherein the light sensor arrangement ( 36 ) measures not only the amount of light emitted per unit area from the light outlet area ( 30 ) but also the diameter of the light outlet area ( 30 ), whereby it can be determined if the optical characteristics of the light curing unit is or is not sufficient to properly cure a dental restoration.

2. The light measurement apparatus as claimed in claim 1 , wherein a prefabricated light sensor arrangement ( 36 ), with a transparent cover ( 38 ), is installed in the base unit.

3. The light measurement apparatus as claimed in claim 1 , wherein the base unit has a stop ( 42 ) for the light guide apparatus ( 24 ) to make contact with.

4. The light measurement apparatus as claimed in claim 1 , wherein the light sensor arrangement ( 36 ) has light sensors ( 40 a , 40 b , 40 c , . . .)which are arranged in a row, and wherein the longitudinal extent of the row is greater than the light outlet area.

5. The light measurement apparatus as claimed in claim 3 , wherein the light outlet area ( 30 ) covers at least one light sensor when the light guide apparatus ( 24 ) is making free contact with the stop ( 42 ).

6. The light measurement apparatus as claimed in claim 1 , wherein the light outlet area ( 30 ) is essentially circular, and the light sensors ( 40 a , 40 b , 40 c , . . . ) each have a width which is less than the width of the light outlet area ( 30 ) that occurs, are arranged immediately adjacent to one another.

7. The light measurement apparatus as claimed in claim 1 , wherein the light sensor arrangement ( 36 ) is an arrangement of light sensors ( 40 a , 40 b , 40 c , 40 d , . . . ) in the form of a strip of between three and five hundred light sensors.

8. The light measurement apparatus as claimed in claim 1 , wherein each light sensor ( 40 a , 40 b , 40 c , . . . ) has an aspect ratio (width/length ratio) of at least 2:1 and at most 20:1.

9. The light measurement apparatus as claimed in claim 1 , wherein the light outlet area ( 30 ) is essentially circular, and wherein the light sensor arrangement ( 36 ) has a length of more than 10-times the diameter of the light outlet area.

10. The light measurement apparatus as claimed in claim 2 , wherein the cover ( 38 ) is covered by a translucent or transparent filter which essentially compensates for the spectral sensitivity of the sensors in the light sensor arrangement ( 36 ).

11. The light measurement apparatus as claimed in claim 10 wherein a protective shutter is fitted to the filter or to the cover ( 38 ), which leaves free an area in the form of a slot above the light sensor arrangement ( 36 ) and covers areas to the side of this area.

12. The light measurement apparatus as claimed in claim 1 , wherein the light outlet area ( 30 ) can be used for different light guide apparatuses ( 24 ).

13. The light measurement apparatus as claimed in claim 1 , wherein a discriminator is connected to one light sensor ( 40 a , 40 b , 40 c , . . . ) and emits an ON signal when the detected amount of light is above a predetermined threshold value, and emits an OFF signal when the amount of light is below the threshold value.

14. The light measurement apparatus as claimed in claim 1 , wherein an evaluation circuit is connected to the light sensor arrangement ( 36 ) and forms the ratio of the amount of light detected by the light sensors ( 40 a , 40 b , 40 c , . . . ) to the number of light sensors ( 40 a , 40 b , 40 c , . . . ) which receive light and are adjacent to one another.

15. The light measurement apparatus as claimed in claim 14 , wherein the light power which is emitted from the light outlet area ( 30 ) is calculated by the evaluation circuit on the basis of the ratio of the amount of light measured by the light sensors ( 40 a , 40 b , 40 c , . . . ) over their area and the total light outlet area ( 30 ).

16. The light measurement apparatus as claimed in claim 3 , wherein the light sensor arrangement ( 36 ) is in the form of a single-line or multiple-line bar, at one of whose ends the stop for the light guide apparatus ( 24 ) is arranged.

17. The light measurement apparatus as claimed in claim 1 , wherein the number of sensors illuminated by the light guide apparatus ( 24 ) is determined by an evaluation circuit, and the average amount of light applied to the sensors is calculated in order to calculate the light power per unit area of a light source.