Incandescent lamp and a lighting apparatus using the lamp

Lighting apparatus comprising:

• an incandescent lamp which includes:
• an envelope having a bulbous portion including a wall defining a space, a thin tube extending outwardly along a central axis of said bulbous portion so as to communicate with said space, and a sealed portion located on an opposite end of said bulbous portion from said thin tube, said wall having a slope inclined toward said thin tube,
• a filament provided along said central axis of said bulbous portion,
• an optical interference layer arranged on a surface of said wall for reflecting infrared rays toward said filament,
• a first lead wire having a first end portion fixed in said sealed portion of said envelope, a second end portion coupled to one end of said filament and an intermediate U-shaped portion inserted into said thin tube for regulating a position of said filament, and
• a second lead wire having a first end portion fixed in said sealed portion of said envelope and a second end portion coupled to another end of said filament;
• and
• a luminaire housing said incandescent lamp.