A double-knife-edge differential detection device, detection method and data processing method for focal length detection
A detection device and double-blade technology, applied in the field of optical detection, can solve the problems of difficult focus accurate positioning, long optical path of detection light, difficulty in eliminating the influence of focal length detection accuracy, etc., and achieve the effect of improving accuracy and good anti-interference ability.
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Embodiment 1
[0046] like figure 1 As shown, it is a double-knife-edge differential detection device for focal length detection. Along the direction of the optical path, the device mainly includes a light source (1), a beam focusing lens group (2), a first beam splitting element (3), and a reflection element group ( 4, 5, 6, 7, 8, 9), filter pinholes (10, 11), second beam splitting element (12), optical element under test (13), cutting edge (14, 15), digital imaging system (16).
[0047]When the light emitted by the light source (1) is focused by the two focusing lenses of the beam focusing lens group (2), the first beam splitting element (3) divides the focused beam into two beams of light with equal light intensity and perpendicular directions. After the light beams are respectively reflected by the reflective element group, they are focused into two point light sources at the two filter holes (10, 11), and the light beams filtered by the filter holes (10, 11) pass through the second bea...
Embodiment 2
[0051] This embodiment is a specific description of the focus detection method based on the aforementioned double-knife-edge differential focus detection device. The detection method includes the following steps:
[0052] S1, adjust the focus detection device so that the two filter holes (10, 11) are placed at a certain position near the focus of the optical element under test (13), and are symmetrical with respect to the optical axis of the optical element under test (13);
[0053] The vicinity of the focus includes before the focus, at the focus and after the focus;
[0054] like figure 1 The spherical reflector shown is placed at the center of curvature of the sphere, and optical components such as focusing lenses and aspheric reflectors can also be tested in other embodiments.
[0055] S2, moving the cutting edges (14, 15) symmetrically toward or away from each other to perform light cutting operation;
[0056] S3, using the digital imaging system (16) to collect the sha...
Embodiment 3
[0064] In the foregoing embodiment 2, in order to perform focus detection, the focus detection device is used to detect and obtain the shadow difference map collected by the digital imaging system (16), and judge whether the focus is in focus according to the change of the differential shadow in the shadow difference map. , and this embodiment provides a data processing method for digitally determining the focus position, the specific steps are as follows:
[0065] (1). Place two symmetrical point light sources at a certain position near the focal point of the optical element under test (13);
[0066] (2). Let the symmetrical cut-off knife edge (14, 15) move the light-cut light towards or opposite to each other, so that the imaging of the point light source in the digital imaging system (16) changes from full bright to full dark, and on the knife edge motion path Capture and record n images at equal intervals to analyze whether the light source is in focus;
[0067] (3). Co...
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