Lens testing device

Abstract

A lens testing device includes a light source assembly, a pattern plate, and an imaging sensor. The light source assembly includes a transparent base plate, a light guide plate, and a number of illuminants. The light source assembly uses the light guide plate to uniformize light coming from the illuminants and emit the light onto the pattern plate. The imaging sensor is placed beneath the transparent base plate to sense the light passing through the pattern plate and focused by a lens under test.

What is claimed is: 
     
         1 . A lens testing device for testing a modulation transfer function of a lens, the lens testing device comprising:
 a pattern plate defining a plurality of patterns;   an imaging sensor; and   a light source assembly comprising:
 a transparent base plate comprising an upper surface, the transparent base plate defining a first receiving space above the upper surface, and a through hole configured for accommodating the pattern plate; 
 a light guide plate comprising a light incident surface, a light emitting surface perpendicular to the light incident surface, and a plurality of microstructures formed on the light emitting surface; and 
 at least one illuminant; 
   wherein the light guide plate is accommodated in the first receiving space with the light emitting surface facing the upper surface, the at least one illuminant is placed on the upper surface and faces the light incident surface for emitting light into the light guide plate, the microstructures are configured to guide the light out of the light guide plate, and the imaging sensor is placed at an opposite side of the base plate to the light guide plate.   
     
     
         2 . The lens testing device as claimed in  claim 1 , wherein the base plate further comprises a lower surface, two opposite parallel first side surfaces perpendicularly connected to the upper surface, and two opposite parallel second side surfaces, the lower surface is parallel to the upper surface, and the first side surfaces are perpendicularly connected to the upper surface, the lower surface, and the second side surfaces. 
     
     
         3 . The lens testing device as claimed in  claim 2 , wherein the base plate further comprises a pair of parallel positioning protrusions perpendicularly extending outwards from the upper surface adjacent to the second side surfaces, the positioning protrusions extend along a direction perpendicular to the first side surface, and the first receiving space is defined between the positioning protrusions. 
     
     
         4 . The lens testing device as claimed in  claim 3 , wherein two second receiving spaces are defined at outer flanks of the positioning protrusions, respectively, the at least one illuminant is a plurality of illuminants, and the illuminants are accommodated in the second receiving spaces and are equidistantly spaced from one another in each of the second receiving spaces. 
     
     
         5 . The lens testing device as claimed in  claim 4 , wherein the light guide plate further comprises a first light reflecting surface parallel to the light emitting surface, and another light incident surface, the two light incident surfaces are located at opposite ends of the light guide plate, and the illuminants are placed corresponding to the light incident surfaces. 
     
     
         6 . The lens testing device as claimed in  claim 5 , further comprising a reflective sheet, wherein the reflective sheet comprises a second light reflecting surface over the first receiving space and the second receiving spaces, and the second light reflecting surface faces the first light reflecting surface. 
     
     
         7 . The lens testing device as claimed in  claim 1 , wherein the at least one illuminant is selected from the group consisting of a fluorescent lamp, a cold cathode fluorescent lamp, and a light emitting diode. 
     
     
         8 . The lens testing device as claimed in  claim 1 , wherein the microstructures are selected from the group consisting of hemispherical bumps and hemispherical recesses. 
     
     
         9 . The lens testing device as claimed in  claim 1 , wherein the patterns include four groups of patterns respectively formed at four corners of the pattern plate, each group of patterns comprises two pairs of stripes perpendicular to each other, and the density of each of the stripe pairs is different in each group. 
     
     
         10 . A lens testing device for testing a lens, the lens testing device comprising:
 a pattern plate defining a plurality of patterns;   a transparent base plate comprising a slot receiving the pattern plate therein, the pattern plate substantially parallel to the base plate;   a light guide plate attached on the base plate, the light guide plate having a light incident surface and a light emitting surface substantially perpendicular to the light incident surface, the light emitting surface facing the pattern plate;   at least one illuminant facing the light incident surface; and   an image sensor arranged at an opposite side of the base plate to the light guide plate to capture an image of the patterns.   
     
     
         11 . The lens testing device as claimed in  claim 10 , wherein the base plate further comprises an upper surface, a lower surface, two opposite parallel first side surfaces perpendicularly connected to the upper surface, and two opposite parallel second side surfaces, the lower surface is parallel to the upper surface, and the first side surfaces are perpendicularly connected to the upper surfaces, the lower surface, and the second side surfaces. 
     
     
         12 . The lens testing device as claimed in  claim 11 , wherein the base plate defines a first receiving space above the upper surface, and the light guide plate is accommodated in the first receiving space with the light emitting surface facing the upper surface. 
     
     
         13 . The lens testing device as claimed in  claim 11 , wherein the base plate further comprises a pair of parallel positioning protrusions extending from the upper surface, the positioning protrusions extend along a direction perpendicular to the first side surfaces, and the first receiving space is defined between the positioning protrusions. 
     
     
         14 . The lens testing device as claimed in  claim 13 , wherein two second receiving spaces are defined at outer flanks of the positioning protrusions, respectively, the at least one illuminant is a plurality of illuminants, and the illuminants are accommodated in the second receiving spaces and are equidistantly spaced from one another in each of the second receiving spaces. 
     
     
         15 . The lens testing device as claimed in  claim 14 , wherein the light guide plate further comprises a first light reflecting surface parallel to the light emitting surface, and another light incident surface, the two light incident surfaces are located at opposite ends of the light guide plate, and the illuminants are placed corresponding to the light incident surfaces. 
     
     
         16 . The lens testing device as claimed in  claim 14 , further comprising a reflective sheet, wherein the reflective sheet comprises a second light reflecting surface over the first receiving space and the second receiving spaces, and the second light reflecting surface faces the first light reflecting surface. 
     
     
         17 . The lens testing device as claimed in  claim 10 , wherein the at least one illuminant is selected from the group consisting of a fluorescent lamp, a cold cathode fluorescent lamp, and a light emitting diode. 
     
     
         18 . The lens testing device as claimed in  claim 10 , wherein the microstructures are selected from the group consisting of hemispherical bumps and hemispherical recesses. 
     
     
         19 . The lens testing device as claimed in  claim 10 , wherein the patterns include four groups of patterns respectively formed at four corners of the pattern plate, each group of patterns comprises two pairs of stripes perpendicular to each other, and the density of each of the stripe pairs is different in each group.