Optical surface profile measuring device

An optical surface profile measuring device having a first measuring light projecting optical system including therein a first light source, a first collimator lens and an objective lens to project a first measuring light onto a surface to be measured, a light transmitting system including therein said objective lens and a beam splitter to transmit the reflected light from the measured surface, and a detecting system including a plurality of photosensors arranged to receive said reflected light divided by said beam splitter and to emit an output in accordance with a distance between said measured surface and focal point of said objective lens, said optical surface profile measuring device further comprising:

• a second measuring light projecting optical system including therein a second light source, a second collimator lens and said objective lens to project a second measuring light onto the measured surface, a light beam width of said first collimator lens being different from a light beam width of said second collimator lens, said first and second measuring light projecting optical systems being arranged to both measure the same portion of said measured surface.

An optical surface profile measuring device having a measuring light projecting optical system including therein a light source, a collimator lens, a polarization beam splitter, a 1/4-wave plate and an objective lens to project a measuring light onto a surface to be measured;

• a light transmitting system including therein said objective lens, said 1/4-wave plate and said polarization beam splitter to lead the reflected light from the measured surface outside of said measuring light projecting optical system;
• and a detecting system including therein a critical angle prism capable of reflecting the reflected light from the measured surface led through said light transmitting system and a photosensor arranged to receive the reflected light from said critical angle prism and to emit an output in accordance with a distance between said measured surface and said objective lens, characterized in that said optical surface profile measuring device further comprises aperture stop means arranged between said polarization beam splitter and said critical angle prism in said light transmitting system to make a numerical aperture of said detecting system smaller than a numerical aperture of said measuring light projecting optical system.

An optical surface profile measuring device having a measuring light projecting optical system including therein a light source, collimator lens, polarization beam splitter, 1/4-wave plate and objective lens to project a measuring light onto a surface to be measured;

• a light transmitting system including therein said objective lens, said 1/4-wave plate and said polarization beam splitter to lead the reflected light beam from the measured surface outside of said measuring light projecting optical system;
• and a detecting system including therein a critical angle prism capable of reflecting the reflected light from the measured surface led through said light transmitting system and a photosensor arranged to receive the reflected light from said critical angle prism and to emit an output to detect whether the measured surface is in focus position or not, characterized in that said optical surface profile measuring device further comprises:
• an aperture stop means arranged between said critical angle prism and said photosensor in said detecting system to make the numerical aperture of said detecting system smaller than the numerical aperture of said measuring light projecting optical system.