ST-VISis dedicated tool for laser bar inspection in production environment. This system inspects around 50 laser bars in hour for any visible defects in (sub threshold) near field or at surface of exit facet. While doing this system provides also accurate measurement from laser bar overhang and smile.
ST-VIS classifies all images and measurement results to passed / failed by internal criteria / failed by external criteria. These rulings may be used to see which bars can be sold, when bars can be sold although they have some defects and when bars are too defective to be sold. ST-VIS also provides systematic way to find defects. For example result stored to database can be: Emitter 18 had too large defect, and its overhang was too big (22.1 µm).
The facet inspection option can be used to detect particles, cracks and coating defects down to 1 µm in diameter. With this option a microscope is used to take an image from front facet which can be analyzed either by the user or by machine vision software.
We have developed measurement modes that work in conjugation with facet inspection using same camera and opto-mechanics. These new measurement options are sub-threshold NF imaging and overhang measurement. Sub threshold imaging of NF helps system to find defects that are difficult to find using regular machine vision imaging methods. This option provides enhanced defect detection. With this mode facet inspection (NF and visual) and overhang measurement can be done in less than 75 s per bar (19 visual inspection images, 19 NF images and overhang measurement). This enables inspection of more than 300 laser bars per day.
Second new mode, overhang measurement, allows system to use focus data from laser diode facet and from submount to determine overhang of laser bar. Overhang of the bar is measured from both edges of bar and for single emitters measurement is done at the centre. This verification is important in order to qualify bar mounting process.
High precision smile measurement entity. Contains high resolution low distortion microscope and enhanced vibration isolation. This can be used to measure laser bars smile with +/- 0.2 µm accuracy (95% of confidence). Although system is vibration isolated, due to extreme accuracy of measurement, system must be installed in space without excessive noise and vibrations to reach specified accuracy.
|DUT’s per Load tray||8,16 or 24|
|Throughput||0.5-2 DUTs/min||For 19-47 emitter bars|
|Particle regognition||1 µm|
|Near-field continuity check||Yes|
|Smile measurement resolution||100 nm|
|Smile measurement repeatability||+/- 250 nm||Typical|
|Overhang resolution||100 nm|
|Near-field laser drive current||0.1-100 mA||Auto-adjusting|
|SQL database support||Yes|
|Offline results browser||Yes|
|Dimensions||1200 x 750 x 1500 mm|
|Power||230 VAC, 5A, 1-phase|