Abstract: A projection lens includes a first lens group, a second lens group and an aperture stop. The first lens group is disposed between a reduced side and a magnified side. The second lens is disposed between the first lens group and the magnified side. The second lens group has a light incident surface, a reflective surface and a light emitting surface, the light incident surface faces the first lens group, the light emitting surface faces a projection surface, the light incident surface, the light emitting surface and the first lens group are disposed at a single side of the reflective surface, and at least one of the light incident surface, the reflective surface and the light emitting surface is a freeform surface. The aperture stop is disposed between the first lens group and the second lens group. Moreover, a projection apparatus including the projection lens is also provided.

Abstract: A dental bracket has a base and an engaging unit. The base has two engaged protrusions and two limiting protrusions. The engaging unit is mounted on the base and forms a space between the base and the engaging unit. The engaging unit has a plate, two engaging arms, and a blocking protrusion. The plate has a first surface and a second surface being flat and opposite the first surface. The two engaging arms are formed on the first surface of the plate and respectively engaged with the two engaged protrusions of the base. The blocking protrusion is formed on the first surface of the plate, is arranged between the two limiting protrusions of the base, and divides the space into two channels for inserting an archwire. The second surface of the engaging unit is flat and is able to decrease the foreign body sensation in the mouth.