wjc@XN.LL.MIT.EDU (Bill Chiarchiaro) (11/22/88)
Last night I received some literature from NEC. One item was a preliminary data sheet on the NDL3200 AlGaInP laser diode. Here are some of the key pieces of information: Typical performance at Ta=25 deg. C Operating Voltage 2.3 V Optical Output Power 3.0 mW Threshold Current 90 mA Operating Current 100 mA Peak Emission Wavelength 670 nm Vertical Beam Angle* 35 deg Lateral Beam Angle* 7 deg * full angle at half maximum Also in the package was Application Note LEA-1011 which describes APC (automatic power control) and protection circuits. The note has a 1985 copyright date which makes me think that it was written for use with IR, CW laser diodes. However, the NDL3200 seems quite similar to the older, IR devices. The output power of the lasers is fairly sensitive to temperature (at a constant drive current). Therefore, a PIN photodetector is included in the device. This is used in a feedback loop in the APC circuit to keep the output power constant. Careful circuit design is essential; it is apparently very easy to fry these lasers. NEC intends these lasers to be used in bar code readers and in pointers. Although they have a wide beam, it should be easy to collimate. I received this literature by calling the NEC America headquarters in California; I thought I had the phone number with me, but I don't. I believe the city is Mountain View. They had quoted me a single-unit price of $260.00. Local distributors' prices seem to range from a little less than that to over $500.00. I'm sure everyone will agree that this is a device which will only get cheaper with time, and probably pretty quickly. Bill