Edge sealant application for optical devices
Techniques are described for applying an edge sealant to the edge of a multi-layer optical device. In particular, embodiments provide an apparatus that performs a precision measurement of the perimeter of an eyepiece, applying the edge sealant (e.g., polymer) based on the precision-measured perimeter, and subsequently cures the edge sealant, using ultraviolet (UV) light that is directed at the edge sealant. The curing process may be performed within a short time following the application of the edge sealant, to ensure that any wicking of the edge sealant between the layers of the eyepiece is controlled to be no greater than a particular depth tolerance. In some examples, the edge sealant is applied to the optical device prevent, or at least reduce, the leakage of light from the optical device, and also to ensure and maintain the structure of the multi-layer optical device.
1. An apparatus for applying an edge sealant to an eyepiece, the apparatus comprising:
a chuck that secures the eyepiece to rotate with the chuck while the chuck rotates, the eyepiece comprising multiple optics layers;
a perimeter measurement component including:
a bearing mechanism comprising a bearing and a spring that allows the bearing to move in a transverse direction while the bearing is rotating, and that causes the bearing to maintain contact with an edge of the eyepiece while the eyepiece is rotating during a first operational phase to generate a perimeter measurement indicating a displacement of the bearing in the transverse direction while the bearing moves along a perimeter of the eyepiece, the transverse direction being substantially parallel to a broad surface of the eyepiece; and
a recording component that generates and stores the perimeter measurement of the perimeter of the eyepiece during the first operational phase, the perimeter measurement being based on detected movement of the bearing in the transverse direction while the bearing is rotating and in contact with the edge of the eyepiece while the eyepiece is rotating;
a sealant applicator that applies the edge sealant to the edge of the eyepiece according to the perimeter measurement while the eyepiece is rotating, during a second operational phase after the first operational phase, wherein the sealant applicator applies the edge sealant to the multiple optics layers of the eyepiece during a single sealant application operation during which a position of the sealant applicator is adjusted to maintain the sealant applicator at a substantially consistent distance in the transverse direction from the edge of the eyepiece according to the perimeter measurement; and
a curing component that cures the edge sealant during a third operational phase.
2. The apparatus of claim 1 , wherein the rotating chuck applies at least a partial vacuum to one side of the eyepiece to secure the eyepiece against the rotating chuck.
3. The apparatus of claim 1 , wherein an outer surface of the bearing, which is in contact with the edge of the eyepiece during generation of the perimeter measurement, is composed of a plastic.
4. The apparatus of claim 1 , wherein the curing component includes multiple ultraviolet (UV) light sources that direct UV light toward the edge sealant during the third operational phase.
5. The apparatus of claim 4 , wherein the multiple UV light sources include at least one UV light source directed along a plane defined by the edge of the eyepiece and at least one UV light source directed perpendicularly to the plane defined by the edge of the eyepiece.
6. The apparatus of claim 1 , wherein the third operational phase is performed within a maximum threshold period of time following completion of the second operational phase, to prevent the edge sealant from wicking, between the multiple optics layers of the eyepiece, farther than a maximum tolerance depth.
7. The apparatus of claim 1 , wherein the curing component cures the edge sealant during the third operational phase according to the perimeter measurement while the rotating chuck is rotating with the secured eyepiece.
8. The apparatus of claim 1 , further comprising a quality control (QC) component that performs in-line QC of the eyepiece, the QC component including a laser micrometer to measure thickness of the eyepiece and a vision camera to measure edge band thickness and wicking length of the edge sealant.
9. The apparatus of claim 1 , wherein the eyepiece is a left eyepiece, the left eyepiece has a common area with a right eyepiece, and the chuck is configured to secure the left eyepiece and the right eyepiece within the common area.
10. The apparatus of claim 1 , wherein the sealant applicator is configured to apply the edge sealant to the edge of the eyepiece such that a thickness of the applied edge sealant in the plane of the eyepiece is in a range between about 80 microns and about 250 microns.
11. The apparatus of claim 1 , wherein the curing component is adjusted to maintain the curing component at a substantially consistent distance in the transverse direction from the edge of the eyepiece according to the perimeter measurement, during the third operational phase.