| 摘要 |
PURPOSE:To perform measurement in a short time and to change the temperature of an element readily by only changing the current of the element, by the constitution, wherein time for increasing element temperature depends only on the thermal time constant of the element. CONSTITUTION:When a current I exceeds a threshold current value Ith of a semiconductor laser, a light output Po is rapidly increased and laser oscillation is started. At this time, when the temperature of an element is increased from a temperature Ta to a temperature Tb, the threshold current value Ith is increased. Instead of observing the temperature characteristic of Ith, the temperature characteristic of an operating current Iop at the constant light output Po is measured. At this time, when the light output Po is made sufficiently small, a large error is not yielded. As a means for heating the element, an operating current Iop2 corresponding to the specified to the specified light output Po1 is made to flow during a heating period from an element time t1 to t2; and an operating current Iop1 required for the specified light output is made to flow during a measuring period from a time t2 to t3. Then, the heating period (t1-t2) is made sufficiently longer than the thermal time constant of the element. Meanwhile, the measuring period (t2-t3) is made sufficiently shorter than said thermal time constant.
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