Abstract: A circumferential portion of an epitaxial wafer is removed to remove an anomalously grown elevated portion formed in a circumferential chamfer. An epitaxial layer in the circumferential portion is removed with a width q=t to 5t wherein t is the thickness of the epitaxial layer so that the surface of a substrate is exposed. Therefore, cracking of the epitaxial layer in processing steps can be prevented.

Abstract: With a semiconductor laser chip that is an inspection object being pushed up from the back surface of an adhesive sheet by a push-up member and the semiconductor laser chip being positioned above the other semiconductor laser chips, the images of both light-emitting end surfaces of the semiconductor laser chip are taken with CCD cameras. Then, on the basis of information of an image taken by the CCD cameras, an visual inspection unit built in a computer determines the goodness or badness of the appearance of the semiconductor laser chip.

Abstract: A clamping jig for mounting semiconductor laser bars includes: multiple supporting bars for holding laser bars therebetween; a pair of supporting plates each of which has a mounting face for mounting the supporting bars in a row; a pressing member for pressing the supporting bars for holding the laser bar; pressing cover members for covering both ends of each supporting bar to prevent supporting bars from falling from the supporting plate; and a supporting frame for detachably supporting the supporting plates and pressing cover members. Each supporting bar is formed with a longitudinal length greater than the laser bar, within a predetermined length so as to be mounted within the supporting frame. Both of the pair of supporting plates may be mounted so as to face one another, or just one may be mounted with the pressing cover members being mounted on the supporting frame instead of the other supporting plate.

Abstract: A circumferential portion of an epitaxial wafer is removed to remove an anomalously grown elevated portion formed in a circumferential chamfer. An epitaxial layer in the circumferential portion is removed with a width q=t to 5t wherein t is the thickness of the epitaxial layer so that the surface of a substrate is exposed. Therefore, cracking of the epitaxial layer in processing steps can be prevented.

Abstract: A clamping jig for mounting semiconductor laser bars includes: multiple supporting bars for holding laser bars therebetween; a pair of supporting plates each of which has a mounting face for mounting the supporting bars in a row; a pressing member for pressing the supporting bars for holding the laser bar; pressing cover members for covering both ends of each supporting bar to prevent supporting bars from falling from the supporting plate; and a supporting frame for detachably supporting the supporting plates and pressing cover members. Each supporting bar is formed with a longitudinal length greater than the laser bar, within a predetermined length so as to be mounted within the supporting frame. Both of the pair of supporting plates may be mounted so as to face one another, or just one may be mounted with the pressing cover members being mounted on the supporting frame instead of the other supporting plate.

Abstract: A defect detection circuit capable of accurately detecting a defect existing in correspondence with a time period in which the operation of an optical disk unit is changed from recording operation to reproducing operation or from reproducing operation to recording operation. When the operation of the optical disk unit is changed, a mono-multi circuit outputs a signal MM1 for turning on the switch in an integration circuit to reduce the time constant of the integration circuit. A logic circuit is supplied with a defect detection circuit DD output from a comparator and the output signal MM1 from the mono-multi circuit, executes a computation to make ineffective the signal MM1 during a time period during which the defect detection signal DD indicates the existence of a defect, and outputs a signal CP to the switch in the integration circuit.

Abstract: A defect detection circuit capable of accurately and rapidly detecting a defect regardless of the operating speed of an optical disk unit. During high-multiplied-speed operation of the optical disk unit, an output duration t1 of a mono-multi signal MM1 output from a mono-multi circuit (11) for turning on a switch (6) is set by a mono-multi time adjustment device (9) to a shorter time, thereby to shorten the time period t1 during which a time constant of an integration circuit (3) is reduced after the operation of the optical disk unit is changed from recording operation to reproducing operation.

Abstract: Signals (A, B, C, and D) obtained by reading information recorded on an optical disk are summed and amplified by an summing amplifier (N1) to generate an RF signal. The RF signal is detected by a detection circuit (N5) to obtain an off-track sate detection signal. If the off-track state detection signal repeatedly alternates between an off-track state and an on-track state, a duty detection unit (N8) measures the duty of the off-track state detection signal. From the result, a sensitivity determining unit (N9) determines the detection sensitivity of the off-track state detection signal in the detection circuit (N5) and a detection sensitivity adjusting circuit (N6) adjusts the detection sensitivity of the off-track state detection signal in the detection circuit (N5).

Abstract: A clamping jig for mounting semiconductor laser bars includes: multiple supporting bars for holding laser bars therebetween; a pair of supporting plates each of which has a mounting face for mounting the supporting bars in a row; a pressing member for pressing the supporting bars for holding the laser bar; pressing cover members for covering both ends of each supporting bar to prevent supporting bars from falling from the supporting plate; and a supporting frame for detachably supporting the supporting plates and pressing cover members. Each supporting bar is formed with a longitudinal length greater than the laser bar, within a predetermined length so as to be mounted within the supporting frame. Both of the pair of supporting plates may be mounted so as to face one another, or just one may be mounted with the pressing cover members being mounted on the supporting frame instead of the other supporting plate.