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Feedback controled mode-locking(FCM) is an effective method to enhance flash-lamp pumped CPM(Colliding pulse mode-locking)・Nd:YAG laser and to reduce the laser pulse width. Generally, the pulse repetition rate of a passively mode-locked laser is represented by the fundamental mode-locking frepuency Δf,which is detennined by the cavity length. As a method of increasing the mode-locking fequency,we set the saturable absorber on 1/14 or 1/6 of cavity length. In this case, the multiple mode-locking frequency is 4Δf, 6Δf, i.e. pulse repetition rate is 500MHz, 750MHz, respectively. In these situations, the pulse train was stretched up to 1200ns, and the pulsewidth was shortened down to 2.6ps in sech2 shape, while the pulse energy was still 5μJ.

The pulsewidth of f1ash-lamp pumped Nd:YAG laser in a linear cavity is signcantly shortened by joint operation of CPM (Colliding Pulse Mode-locking) and FCM (Feedback controled Mode-Locking). Power limiting by the intracavity self-defocusing due to two-photon absorption in GaAs with a pinhole in both sides is exploited to create the optimum condition for the pulse compression in a saturable absorber. We tried to determine the opimum condition of the pinholes namely the dependence of pulse train duration on the position and the diameter of the pinholes. Under the optimum condition, the pulse train was stretched up to 1540ns, and the pulsewidth was shortened down to 2.8ps in sech2 shape, while the pulse energy was still 10μJ.

The pulsewidth of a flash -lamp pumped Nd: YAG laser in linear cavity is significantly shortened by joint operation of CPM (Colliding Mode-locking) and FCM Feedback Controlled Mode-locking). The CPM operation is done with a saturable absorber set at a quarter of the cavity length apart from the end mirror. Four pulses are generated simultaneously in the cavity These pulses collide in the saturable dye cell and also at another quarter apart from the coupling mirror. therfore, the FCM effect can be enhanced by pulse colliding in a GaAs wafer inserted at this position. On this joint operation,the duration of pulse train,in which the pulse interval is 2ns, is extended up to 80ns. The pulsewidth is shortened down to 3.3ps in Gaussian shape (3.Ops sech2),while the pulse energy is 7μJ.

精巣腫瘍36例のパラフィンブロックを用いて, FCMによる核DNA量解析を行った.1) DNAヒストグラムは36例中20例で解析可能であったが, teratomaでは他の組織型に比べて解析不能症例が多かった.2) DNA aneuploidyの出現は20例中11例にみられたが, seminomaとnon-seminomaで組織型の違いによる差はなかった.3) seminomaはstageの進行に伴いaneuploidの出現頻度が高くなった.4) HCG-β値の上昇を認めたseminomaでは, 4例中3例にaneuploidがみられmalignant potentialが高いと推定された, The DNA content of paraffin-embedded materials was determined retrospectively using flow cytometry (FCM) in 36 germ cell tumors, and related to histological type, clinical staging and tumor marker. These histograms were classified from the basis of mode and variance into a diploid and an aneuploid pattern. We could evaluate the DNA histograms in 20 of 36 specimens (56%). Aneuploid patterns were found in 11 of 20 evaluated cases, but there was no correlation between ploidy patterns and histological types. Aneuploid patterns were demonstrated in 2 of 6 stage I cases (33%), and 4 of 5 stage II cases (80%) in seminomas. The difference between stage I and II cases was not statistically significant. There was no correlation between clinical staging and DNA content in non-seminomas. Of the seminomas with elevated human chorionic gonadotropin (HCG) titers, 3 of 4 cases showed aneuploid patterns. These findings indicate that the determination of DNA ploidy in seminomas may prove to be of prognostic value.