摘要:
A base member having a negative coefficient of thermal expansion of -10 to -120 × 10 -7 /°C within a temperature range of -40 to 100 °C is provided with an inner bore formed at a predetermined position thereof. An optical component having a positive coefficient of thermal expansion is disposed in the inner bore. Further, the optical component is fixed to the base member at a plurality of particular positions spaced from one another in an axial direction of the inner bore.