In a high-density sequence detection system, an apparatus for transporting a microplate. A control system provides a thermocycler control signal to regulate a desired thermal output of a thermocycler block. A frame has a first side, a second side, and an opening that extends through the first side and the second side. A window is positioned in the opening and a circumferential seal is positioned around a periphery of the opening at the second side. The seal has a peripheral lip that seals against the microplate. A clamp is adapted to engage and displace the frame from an unclamped position to a clamped position, wherein in the unclamped position, the microplate is displaced away from the thermocycler block and in the clamped position, the clamp urges the microplate against the thermocycler block. In some embodiments the peripheral lip is positioned radially inward of the periphery of the opening.