Optical lens assembly and optical measurement method

1 . An optical lens assembly adapted for receiving a light beam that is emitted by an object, said optical lens assembly comprising:

a lens unit including a casing that has a light-incident side adapted for receiving the light beam;

a sleeve unit surrounding said light-incident side of said casing, and defining a light-receiving space that is adapted for the light beam to pass through so that propagation of the light beam is unaffected by disturbance caused by movement of air,

wherein said sleeve unit includes

a first sleeve that surrounds said casing, and

a second sleeve that is connected to said first sleeve, and that is movable relative to said first sleeve so that a length of said sleeve unit is adjustable, wherein said sleeve unit is removably mounted to said casing of said lens unit; and

a fastening unit surrounding said sleeve unit and operable to tighten said sleeve unit so that said sleeve unit is removably mounted to said casing.

2 . The optical lens assembly as claimed in claim 1 , wherein the length of said sleeve unit ranges from 5 to 50 millimeters.

3 . The optical lens assembly as claimed in claim 1 , wherein:

said first sleeve has an outer flange portion that is located at an end of said first sleeve distal from said casing;

said second sleeve has an inner flange portion that is located at an end of said second sleeve proximate to said casing; and

when the length of said sleeve unit is adjusted to a maximum length, said outer flange portion and said inner flange portion abut against each other.

4 . The optical lens assembly as claimed in claim 1 , wherein said fastening unit includes:

two fastening members that cooperatively surround said first sleeve; and

two securing members that are interconnected to said fastening members, and that cooperate with said fastening members to tighten said first sleeve so that said first sleeve is mounted to said casing.

5 . The optical lens assembly as claimed in claim 1 , wherein said first sleeve of said sleeve unit has an annular groove that is indented from an outer surface thereof, said fastening unit being mounted to said annular groove.

6 . The optical lens assembly as claimed in claim 1 , wherein said first sleeve of said sleeve unit has at least one slot, said fastening unit surrounding said at least one slot such that an inner diameter of a portion of said first sleeve that is surrounded by said fastening unit is adjustable.

7 . An optical measurement method comprising steps of:

a) providing an object that is for emitting a light beam, a fastening unit, a lens unit that includes a casing, which has a light-incident side, and a sleeve unit that surrounds said light-incident side of said casing, that defines a light-receiving space, that includes a first sleeve which surrounds said casing, and a second sleeve which is connected to said first sleeve, and which is movable relative to said first sleeve, a length of said sleeve unit being adjustable, said fastening unit surrounding said sleeve unit and being operable to tighten said sleeve unit so that said sleeve unit is removably mounted to said casing; and

b) operating said lens unit so that the light beam emitted by said object passes through said light-receiving space and is received by said light-incident side of said lens unit, said light receiving space protecting propagation of the light beam therein against disturbance caused by movement of air.