A heat pipe comprises an evaporator section 5 having a radiation absorbing plate 6 a portion of an elongate tube 7, and a condenser section 10 at a distal end of the elongate tube 7 remote from the evaporator section 5. The computer USB HUB and card reader combining device can be a plug-in computer USB HUB and card reader the power of which is supplied from a DC converter or be a built-in computer USB HUB and card reader which can be placed on a computer disk rack and has power from a power supply in the computer Thereby, the user can derive a convenient computer USB HUB and card reader combining device. Preferably, the optical element substantially intercepts the emitted light within a solid angle that has its vertex at the center of the discharge volume of the burner and is subtended by the open end of the reflector. The protective layer is coated on the outer surfaces of the LED devices and the circuit board so as to protect the wiring, the soldering contacts, and the electrical components of the circuit board from being damaged by the high temperature during the process of forming the enclosing member. The apparatus captures multiple images of each crystal site using different light source and polarization conditions, and processes the multiple images to form extended fused images of each crystal site.