Focusing leveling device

1. A focusing and leveling apparatus, comprising: an illumination light source for emanating a light beam; and an illumination lens group, a projecting unit, an object being measured, a detecting unit, a refractive unit, a relay lens group and a photoelectric detector, disposed sequentially in this order in a transmission path of the light beam, the photoelectric detector configured to convert the light beam that has exited the relay lens group and carries information about a level and a tilt of a surface of the object being measured to an electrical signal and pass the electrical signal on to an arithmetic unit and a focusing and leveling controller, the arithmetic unit configured to produce a control signal for the focusing and leveling controller based on the received electrical signal such that the focusing and leveling controller controls a wafer stage that supports the object being measured to adjust the level and tilt of the surface of the object being measured,

wherein the projecting unit comprises projection slits defining a plurality of non-linearly arranged marks, such that after passing sequentially through the illumination lens group, the projecting unit, the object being measured and the detecting unit, the light beam emanated by the illumination light source becomes a plurality of non-linearly arranged sub-beams corresponding to the plurality of marks, and wherein the refractive unit is configured such that the plurality of sub-beams form a plurality of linearly arranged light spots after passing through the refractive unit.

2. The apparatus according to claim 1 , wherein the projection slits define at least three non-linearly arranged marks.

3. The apparatus according to claim 1 , further comprising a double-prism group having two prisms sandwiching the projection slits therebetween.

4. The apparatus according to claim 1 , wherein the refractive unit comprises a reflector group, a lens group and a prism group.

5. The apparatus according to claim 4 , wherein the reflector group consists of n−1 pairs of reflectors, the lens group consists of n lenses, and the prism group consists of n−1 prisms, where n corresponds to a number of the non-linearly arranged marks defined by the projection slits.

6. The apparatus according to claim 5 , wherein: the refractive unit further comprises a parallel-sided plate; a middle one of the plurality of sub-beams incident on the refractive unit passes through a corresponding one of the lenses and is then incident on the parallel-sided plate, and wherein remaining ones of the plurality of sub-beams travel sequentially through corresponding pairs of the reflectors, corresponding ones of the lenses and the prisms, and are then incident, together with the middle sub-beam, on the relay lens group.

7. The apparatus according to claim 1 , wherein the photoelectric detector is a single CCD linear array.

8. The apparatus according to claim 1 , wherein the refractive unit comprises two wedges disposed with sloped faces thereof facing each other.

9. The apparatus according to claim 8 , wherein a first one of the two wedges defines first through-holes in middle and lower parts thereof at locations corresponding to incidence of a middle one and lower ones of the plurality of sub-beams on the first one of the two wedges of the refractive unit, and wherein a second one of the two wedges defines second through-holes in middle and upper parts thereof at locations corresponding to incidence of the middle one and upper ones of the plurality of sub-beams on the second one of the two wedges of the refractive unit.

10. The apparatus according to claim 9 , wherein the refractive unit further comprises a parallel-sided plate arranged such that the middle one of the plurality of sub-beams passes through the first and second through-holes defined in the respective middle parts of the two wedges and is then incident on the parallel-sided plate.