Disclosed is a parallel/series infrared scanner for detecting thermal images. "N" infrared detecting elements are arranged in series to scan a single portion of an I.R. image. Adjacent portions of the I.R. image are scanned by additional elements also arranged in series but parallel to the "N" series of elements. The specific detector elements can be selectively activated in order to compensate for disuniformity among detectors in the series. Thus, it is unnecessary to utilize precisely identical infrared detector elements because the number of activated elements in a single series can be adjusted to provide a uniform output which is precisely matched to the output of the other series of detectors.

An infrared imaging device enabling operation in the panning mode with a very high sensitivity and the facility of viewing a desired part of the observed field. A pyroelectric imaging tube is shifted relative to the observed scene and the infrared image on the target is read in a line by line scan the direction of the line being perpendicular to that in which the image is shifted. The shift takes place at a speed corresponding to a whole number R of line intervals in the course of one image frame scan comprising n=KR lines, with the result that each point is examined K times in the course of K successive frame periods; the video signal is accordingly processed to perform K successive integrations.

A shield or opaque covering for reducing blooming at low input levels in -dimensional charge-injection devices. Two-dimensional charge-injection devices include X-Y aligned detector elements in which each detector element includes a y-electrode portion and a x-electrode portion, each in the same alignment. Each of the y-electrode portions in the same vertical column is connected to a common conductor to form separate y-electrode column conductors, one for each column of elements. Each of the x-electrode portions in the same horizontal row is connected to a common conductor thereby forming separate rows of x-electrode conductors, one for each row of elements. During fabrication each of the rows of y-electrode portions is permanently covered with a covering which is opaque to the radiation to be detected whereas each of the x-electrode areas is exposed to the radiations to be detected. Such an arrangement permits read-out of individual detector elements without blooming by nearby detector elements at low inputs.

The invention relates to an improved readout circuit and readout method for an IR sensing array. The invention, given a limited time interval for reading out the signal from a sensor element in an array of sensor elements, permits a longer time to be devoted to the injection of charges into the substrate, thereby reducing device "lag" (the retention of uninjected charges). The readout is carried out by a two step, direct coupled, injection process. The first step involves independent, but simultaneous resetting of the sensor elements and the preamplifier input (at a node having sufficient capacity to supply the charges required for injection). The voltages are suitable for IR induced charge storage in the sensor elements, and for subsequent injection by the nodal capacity. A first sample is taken by a correlated double sampling circuit from the preamplifier output during the first step as the resetting stabilizes. In the second step, the selected sensor element is connected to the preamplifier input to cause the charge injection. At the same time the preamplifier is responding to the charge transfer. The second sample is taken from the preamplifier output at the end of injection. The reduction in lag over conventional AC coupled readout circuits is 80%.

An integrating IR detector array for imaging is provided in a hybrid circuit with InSb mesa diodes (1, 2 . . . 128) in a linear array, a single J-FET preamplifier (30) for readout, and a silicon integrated circuit multiplexer (34). A reset switch (32) is also provided to reset (charge) all of the diodes to a predetermined level at the end of each line scan. Thin film conductors in a fan-out pattern deposited on an Al.sub.2 O.sub.3 substrate (42) connect the diodes to the multiplexer, and thick film conductors also connect the reset switch and preamplifier to the multiplexer. Two-phase clock pulses (.phi..sub.1 and .phi..sub.2) are applied with a logic return signal to the multiplexer through a triax comprised of three thin film conductors deposited one over the other with silicate glass insulation between layers. A lens (14) focuses a scanned image onto the diode array for horizontal read out one line at a time while a scanning mirror (22) provides vertical scan. A cooler (20) maintains the hybrid circuit at a very low (liquid nitrogen) temperature.