I thought this would be of interest, as it’s from a drive circa 2001, (DVD-CD-RW).
It’s the biggest & most complex optical block I’ve ever seen, with totally separate beam paths for the IR CD beam & the visible DVD beam. It also combines the use of bare laser diodes & combined diode/photodiode array modules for the pickup.
Cover Removed
Here’s a look at the optics inside the sled, on the left is a bare laser diode & photodiode array, for the CD reading, and the bottom right has the DVD combined LD/PD array module. The beam from the CD diode has to pass though some very complex beam forming optics & a prism to fold it round to the final turning mirror to the objective lens at top center.
There are also two separate photodiodes which are picking up the waste beam from the prisms, most likely for power control.
Here is a 2Gbit Fibre Channel transceiver from Cisco Systems in SFP module format.
Shield Removed
Here the shield has been removed from the bottom of the module (it just clips off). The bottom of the PCB can be seen, with the copper interface on the left & the rubber boots over the photodiode & 850 nm laser on the right.
PCB Bottom
Here the PCB has been completely removed from the frame, the fibre ends slide into the rubber tubes on the right.
PCB Top
Top of the PCB, showing the chipset. There are a pair of adjustment pots under some glue, next to the chipset, presumably for adjusting laser power & receive sensitivity. The laser diode & photodiode are inside the soldered cans on the right hand side of the board, with the optics required to couple the 850nm near-IR light into the fibre.
An ICL barcode scanner from the 80s is shown here. This is the top of the unit with cover on.
Cover Removed
Plastic cover removed from the unit showing internal components. Main PSU on left, scan assembly in center. Laser PSU & Cooling fan on right. Laser tube at top.
Scan Motor
Closeup of laser scan motor. This unit scans the laser beam rapidly across the glass plate to read the barcode.
Controller PCB
View of the bottom of the unit, showing the controller PCB in the centre.
Scan Motor Driver
The 3-phase motor driver circuit for the scan motor. 15v DC powered.
Laser Unit
This is the laser unit disconnected from the back of the scanner. HT PSU is on right hand side, beam emerges from optics on left.
Laser Unit Label
This unit is date stamped 1987. The oldest laser unit i own.
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