DTRCI-04 / DUAL PATH · TRANSMISSION + REFLECTION
Observe both sides and switch between transmission and reflection at one station to suit different lens-centering processes.
Product introduction
This instrument adds reflection measurement to transmission inspection and uses two measurement paths. Operators can assess a lens’s overall transmitted centering error or center its front and rear spherical surfaces separately, choosing the mode required by the drawing and production process.
The two paths observe the workpiece from opposite sides, making it easier to compare the centering state of its front and rear surfaces. Compared with repeatedly switching one measuring head between surfaces, two heads can reduce image-finding and preparation time while showing how an adjustment affects both sides.
Switch to transmission to inspect overall transmitted error, or to reflection to center a selected spherical surface. Combining both methods at one station reduces equipment changes between tasks and supports varied lens production and assembly work.
Working principle
A source illuminates a crosshair reticle, and the optics form a collimated beam. After passing through the test lens, it produces a transmitted crosshair image captured by the receiving optics and CCD.
As the lens rotates around the reference axis, image movement reflects the offset of the transmitted focus from that axis. Software tracks the path to support error evaluation and centering adjustments.
Using autocollimation, the measuring optics focus at the selected spherical surface’s center of curvature. The corresponding CCD captures its returned crosshair image.
If the center of curvature is offset from the rotation reference axis, the image follows a periodic path as the workpiece rotates. Under ideal conditions, its radius is proportional to the distance from the center of curvature to that axis. The operator can reduce the surface error by observing how the path changes.
The two paths make it possible to observe reflected images from opposite surfaces separately. During translation or tilt adjustment, operators can compare both surfaces rather than improving one while overlooking the other.
Transmission observes an image formed after light passes through the lens; reflection observes light returned from a selected surface. Switching modes therefore requires the matching illumination, optical-path setting and focus adjustment.
The two modes provide different information and should be assessed against the relevant process requirements. Transmission reflects overall transmitted error; reflection helps analyse the selected surface’s centering error.
Operating guide
Clean the lens, fixture and measuring optics, then secure the part in the rotating fixture. Keep both optical paths clear and leave a safe distance between each measuring head and the workpiece.
Choose transmission or reflection according to the drawing and process. For two-sided reflection inspection, identify which target surface corresponds to each CCD.
Stop rotational measurement before switching modes, and follow the equipment procedure.
For transmission, adjust the receiving path until the transmitted crosshair is sharp. For reflection, find and focus the reflected image from each target surface. If several images appear, use the lens geometry to identify the intended surface.
Set illumination and exposure so crosshair edges are clear without saturation. Choose a measurement region that contains the image throughout a complete rotation.
Capture the crosshair trace at the specified measurement speed. Stop the spindle after reviewing the trace, make a small adjustment, then rotate and measure again.
For two-sided reflection inspection, review both paths. Continue until both target surfaces meet the process requirements, rather than improving one at the expense of the other.
