| 主权项 |
1. A height detecting apparatus comprising:
workpiece holding means for holding a workpiece; height detecting means for detecting the height of said workpiece held on said workpiece holding means; and moving means for relatively moving said workpiece holding means and said height detecting means; said height detecting means including
a light source having a predetermined wavelength band,a first single-mode fiber for transmitting light emitted from said light source,a fiber coupler connected to said first single-mode fiber,a Fabry-Perot tunable filter connected to said first single-mode fiber between said light source and said fiber coupler for sequentially sweeping light having a single wavelength from said wavelength band at predetermined cycles and then transmitting the light having the single wavelength,a chromatic aberration lens for focusing the light transmitted from said Fabry-Perot tunable filter and applying this light to said workpiece held on said workpiece holding means,a second single-mode fiber for transmitting return light reflected from said workpiece, next passed through said chromatic aberration lens, and next branched by said fiber coupler,a photodetector for detecting the return light emerging from said second single-mode fiber and outputting a signal corresponding to the intensity of the return light detected above, andcontrol means having a memory for storing a table setting the relation between wavelength and height; said control means determining the wavelength corresponding to the highest light intensity from the wavelengths detected by said photodetector in synchronism with the predetermined cycles of sweeping of the light having the single wavelength by said Fabry-Perot tunable filter, and then checking this determined wavelength against the wavelength and height set in said table, thereby determining the height of said workpiece held on said workpiece holding means. |
