Fast and wide-field reflective optic system for imaging microplate readers

We present a fluorescence/luminescence imaging system for use in high-throughput screening of samples in microplates. High efficiency imaging of microplates is an optical challenge usually involving performance compromises. Conventional microplate imagers use large refractive systems. These systems typically have many large lenses and suffer from their disadvantages such as low light transmission efficiency, field shading (low uniformity), and weight. Our optical design enables simultaneous detection of light from all of the samples in a microplate with high collection efficiency, high transmission efficiency, low chromatic aberration, high uniformity, and sub-well (submillimeter) resolution all in a relatively small package. Our optical system includes a primary mirror and an on-axis secondary mirror with a central aperture (a reverse-conjugate Schwarzchild arrangement) along with a small set of refractive field correctors. The field correctors compensate for the aberrations induced by the wide field (108x72 mm) without resorting to aspheric mirrors. The prototype of this design met our goals of high transmission, high uniformity and low crosstalk.