Abstract: A projection type exposure apparatus and method comprising an exposure illumination light source, an exposure illumination system, a mask or reticle on which an original pattern to be projected on the exposed matter is drawn, an optical projection system, a stage for retaining the exposed matter and a mechanism for finely moving the stage along the exposure optical axis.

Abstract: A method and apparatus measures an image plane of a test pattern projected onto a surface of a sample disposed on a stage to precisely detect the image plane to thereby obtain a precise alignment therebetween for subsequent exposure. The test pattern is provided on a member having a conjugate surface with an upper surface of an illumination detecting unit having at least three optical sensors at different positions thereof and disposed on the stage. The upper surface of the illumination detecting unit has an analogous pattern to the test pattern on each optical sensor and, by moving the stage three dimensionally, outputs of the optical sensors are processed to obtain amounts of light and peak values thereof from which the image plane is obtained.