Abstract: An optical instrument which has an optical system that includes an ocular lens and a reticle located in the optical system, wherein a phosphorescence pigment is applied to a surface of the reticle facing toward the ocular lens, and light irradiated from outside through the ocular lens excites the phosphorescence pigment of the reticle, The phosphorescence pigment contains at least one of a phosphorescence phosphor selected from SrAl2O4: Eu, Dy; Sr4Al14O25: Eu, Dy; and CaAl2O4: Eu,Nd. The particle diameter of the phosphorescence pigment is no smaller than 1.5 ?m and no greater than 10 ?m at D50. The phosphorescence pigment is applied with a microscopic and sharp shape and thus improves visibility even in dark places. The phosphorescence pigment is applied in an amount that is no less than 1.2 mg/cm2 and no more than 50 mg/cm2. This obtains appropriate luminance and improves visibility even in dark places.

Abstract: A phosphorescence pigment 18 applied to a surface of a reticle 11 contains at least one of a phosphorescence phosphor selected from SrAl2O4: Eu, Dy; Sr4Al14O25: Eu, Dy; and CaAl2O4: Eu, Nd. The phosphorescence pigment applied to the surface of the reticle 11 emits light over a long period of time after being excited and ensures satisfactory visibility over a long period of time even in dark places. The particle diameter of the phosphorescence pigment 18 is no smaller than 1.5 &mgr;m and no greater than 10 &mgr;m at D50. The phosphorescence pigment 18 is applied with a microscopic and sharp shape and thus improves visibility even in dark places. The phosphorescent pigment is applied in an amount that is no less than 1.2 mg/cm2 and no more than 50 mg/cm2 This obtains appropriate luminance and improves visibility even in dark places.

Abstract: A plurality of disc units, an array control unit, and a host controller connecting mechanism for connecting them to a host controller through a system interface are mounted on the same circuit board. The order of interrupts of requests for connecting of disc units is detected, and the disc units are connected to a common bus selectively. Cables for interconnecting constituent elements of the disc array device and supporting mechanisms for the disc units can be dispensed with, and consequently the cost can be reduced. Useless rotation waiting is avoided, improving the data transfer rate. The disc array device can be built in the host device and connected directly to the system bus. Therefore the ease of operation can be improved.