Abstract: A light tunnel includes a first optical element, a second optical element, a third optical element and a fourth optical element. The first optical element has a first recess. The second optical element is disposed opposite to the first optical element and has a second recess. The third optical element connects the first optical element with the second optical element and has one end disposed in the first recess or the second recess. The fourth optical element is disposed opposite to the third optical element, connects the first optical element with the second optical element, and has one end disposed in the first recess or the second recess. Inner surfaces of the first to fourth optical elements form a light passage. A projection system is also disclosed.

Abstract: A light tunnel includes a first optical element, a second optical element, a third optical element and a fourth optical element. The first optical element has a first recess. The second optical element is disposed opposite to the first optical element and has a second recess. The third optical element connects the first optical element with the second optical element and has one end disposed in the first recess or the second recess. The fourth optical element is disposed opposite to the third optical element, connects the first optical element with the second optical element, and has one end disposed in the first recess or the second recess. Inner surfaces of the first to fourth optical elements form a light passage. A projection system is also disclosed.

Abstract: A coating method for a color filter, including the steps of: coating a first photoresist layer on a substrate; forming at least a aligning pattern and a first color film pattern on the first photoresist layer by exposure and development; coating a first dye on the aligning pattern and the first color film pattern; stripping the first photoresist layer; coating a second photoresist layer on the substrate, wherein the aligning pattern and the first color film pattern are formed on the substrate; aligning position by using the aligning pattern of the substrate; forming a second color film pattern on the second photoresist layer by exposure and development; coating a second dye on the second color film pattern; and stripping the second photoresist layer. The invention also discloses an aligning-assembling method for a color wheel, which includes the color filter.

Abstract: A coating method for a color filter, including the steps of: coating a first photoresist layer on a substrate; forming at least a aligning pattern and a first color film pattern on the first photoresist layer by exposure and development; coating a first dye on the aligning pattern and the first color film pattern; stripping the first photoresist layer; coating a second photoresist layer on the substrate, wherein the aligning pattern and the first color film pattern are formed on the substrate; aligning position by using the aligning pattern of the substrate; forming a second color film pattern on the second photoresist layer by exposure and development; coating a second dye on the second color film pattern; and stripping the second photoresist layer. The invention also discloses an aligning-assembling method for a color wheel, which includes the color filter.

Abstract: A coating method for a color filter, including the steps of: coating a first photoresist layer on a substrate; forming at least a aligning pattern and a first color film pattern on the first photoresist layer by exposure and development; coating a first dye on the aligning pattern and the first color film pattern; stripping the first photoresist layer; coating a second photoresist layer on the substrate, wherein the aligning pattern and the first color film pattern are formed on the substrate; aligning position by using the aligning pattern of the substrate; forming a second color film pattern on the second photoresist layer by exposure and development; coating a second dye on the second color film pattern; and stripping the second photoresist layer. The invention also discloses an aligning-assembling method for a color wheel, which includes the color filter.