Multi-modality with TDI sensor

An optical inspection system comprising:

• at least one illumination source configured to generate illumination;
• a multi-mode TDI sensor comprising:
• a plurality of active pixel rows, wherein the plurality of active pixel rows are configured to accumulate charge based on sample light received by the plurality of active pixel rows, wherein the sample light emanates from a sample in response to the illumination;
• a plurality of inactive pixel rows, wherein the plurality of inactive pixel rows are configured to buffer the charge without accumulating additional of the charge in response to receiving the sample light, wherein the plurality of active pixel rows and the plurality of inactive pixel rows alternate in a sequence, wherein the sequence defines a plurality of optical modes for which the multi-mode TDI sensor is configured, wherein the charge is configured to transfer between the plurality of active pixel rows and the plurality of inactive pixel rows in the sequence;
• and
• a readout circuit, wherein the readout circuit is configured to readout the charge as separate images for each of the plurality of optical modes, wherein the optical inspection system is configured to generate the separate images by scanning the sample with the illumination;
• and
• a controller, wherein the controller is configured to control a length to which the sample light is scanned before switching between the plurality of optical modes, wherein the length to which the sample light is scanned before switching between the plurality of optical modes is based on a pixel length divided by the plurality of optical modes.

A method comprising:

• causing a multi-mode TDI sensor to sequentially receive a sample light with a plurality of optical modes, wherein the multi-mode TDI sensor comprises a plurality of active pixel rows, wherein the plurality of active pixel rows are configured to accumulate charge based on the sample light received by the plurality of active pixel rows;
• a plurality of inactive pixel rows, wherein the plurality of inactive pixel rows are configured to buffer the charge without accumulating additional of the charge in response to receiving the sample light, wherein the plurality of active pixel rows and the plurality of inactive pixel rows alternate in a sequence, wherein the sequence defines the plurality of optical modes for which the multi-mode TDI sensor is configured, wherein the charge is configured to transfer between the plurality of active pixel rows and the plurality of inactive pixel rows in the sequence;
• and a readout circuit, wherein the readout circuit is configured to readout the charge as separate images for each of the plurality of optical modes;
• accumulating the charge in the plurality of active pixel rows and transferring the charge between the plurality of active pixel rows and the plurality of inactive pixel rows of the multi-mode TDI sensor as the sample light is sequentially received, wherein a length to which the sample light is scanned before switching between the plurality of optical modes is based on a pixel length divided by the plurality of optical modes;
• and
• reading out the charge via the readout circuit.