MULTI-DIRECTION SFR MEASUREMENT SYSTEM
A multi-directional SFR measurement system includes a rotatable test fixture located within an enclosure. Mounted on the test fixture is a test key for holding a camera module under test, a collimating lens, and a target/light source panel that provides a visible target for imaging by the camera module. A controller box located outside of the enclosure allows an operator to command the system to rotate the test fixture to a desired angle and capture an image of the target with the camera module under test. The system also includes an angle indicator to indicate the rotational angle of the test fixture and an air pressure controller/indicator to control and indicate the air pressure of the system used for positioning the collimating lens relative to the test fixture.
1 . A system for testing a camera module under test, comprising:
a test stand;
a rotatable test fixture rotatably attached to the test stand, the test fixture accepting a camera module under test; and
a target to be imaged by the camera module under test, the target being interconnected to the test fixture.
2 . A system as defined in claim 1 , further including a collimating lens interconnected to the test fixture, the collimating lens receiving light from the target and refracting the light toward the camera module under test.
3 . A system as defined in claim 2 , wherein the system is operated by a user, wherein the position of the collimating lens relative to the test fixture is controlled by air pressure, and further including an air pressure controller interconnected to the test fixture and fluidly connected to the interconnection of the collimating lens to the test fixture.
4 . A system as defined in claim 3 , wherein the air pressure controller includes a fluid control actuator for the user to actuate to vary the air pressure.
5 . A system as defined in claim 3 , wherein the air pressure controller includes an air pressure gauge to provide an indication to the user of the air pressure.
6 . A system as defined in claim 1 , wherein the camera module under test is attached to a test jig which is attached to the test fixture, and wherein the collimating lens is also attached to the test jig.
7 . A system as defined in claim 6 , wherein the collimating lens further includes a stopper of a predetermined length that is used to provide a predetermined spacing between the lens and the camera module under test.
8 . A system as defined in claim 7 , wherein the system includes a controller associated therewith for controlling operation of the camera module under test.
9 . A system as defined in claim 8 , wherein the controller also controls an angle of rotation of the rotatable test fixture.
10 . A system as defined in claim 1 , wherein the target includes at least one resolvable object in a center portion thereof and at least one resolvable object in a peripheral region thereof.
11 . A system as defined in claim 10 , wherein the target is in the shape of a rectangle and the at least one resolvable object in the peripheral region include at least four resolvable objects, one in each of four corners of the rectangle.
12 . A system as defined in claim 1 , wherein the target is interconnected to the test fixture in a manner that allows for the distance between the target and the test fixture to be adjusted.
13 . A system as defined in claim 1 , wherein the target is directly attached to a light source panel that provides backlighting to the target.
14 . A system as defined in claim 1 , wherein the frame is in the shape of a box with lateral sidewalls and all of the lateral sidewalls include glass between members of the frame, so as to enclose the lateral sidewalls.
15 . A system as defined in claim 1 , wherein the system is operated by a user, and further including an angle indicator interconnected to the test fixture in a manner to maintain the same angular relationship between the angle indicator and the test fixture in order to provide an indication to the user of the angular position of the test fixture.
16 . A method for testing a camera module under test, comprising:
affixing the camera module under test to a rotatable test fixture;
rotating the test fixture to a desired angle; and
capturing an image of a target with the camera module under test, the target being interconnected to the test fixture.
17 . A method as defined in claim 16 , further including image processing the captured image to determine the spatial frequency response of the camera module under test.
18 . A method as defined in claim 17 , wherein the image processing includes determining the spatial frequency response at various points in the captured image.
19 . A method as defined in claim 16 , wherein the rotating and capturing operations are repeated for a plurality of angles.
20 . A method as defined in claim 16 , further including providing a collimating lens interconnected to the test fixture, the lens being located between the target and the camera module under test.