Apparatus for determining a property of a biological sample, the apparatus comprising: a sample carrier that comprises one or more sample chambers configured to house the sample, the one or more sample chambers defining at least first , second , and third regions thereof, a height of the one or more sample chambers varying between the first, second, and third regions in a predefined manner, wherein the varying heights of the individual regions of the one or more sample chambers each differ by a predefined height difference; and a computer processor configured to: determine a signal level of the biological sample, based upon the determined signal level, select two out of the first, second, and third regions upon which to perform, respectively, first and second optical measurements, receive data relating to the first optical measurement that is performed upon a portion of the sample that is disposed within a first one of the selected regions, receive data relating to a second optical measurement that is performed upon a portion of the sample that is disposed within a second one of the selected regions, and determine the property of the sample by using a relationship between the first optical measurement, the second optical measurement, and the predefined height difference between the first selected region and the second selected region. a sample carrier that comprises one or more sample chambers configured to house the sample, the one or more sample chambers defining at least first , second , and third regions thereof, a height of the one or more sample chambers varying between the first, second, and third regions in a predefined manner, wherein the varying heights of the individual regions of the one or more sample chambers each differ by a predefined height difference; and a computer processor configured to: determine a signal level of the biological sample, based upon the determined signal level, select two out of the first, second, and third regions upon which to perform, respectively, first and second optical measurements, receive data relating to the first optical measurement that is performed upon a portion of the sample that is disposed within a first one of the selected regions, receive data relating to a second optical measurement that is performed upon a portion of the sample that is disposed within a second one of the selected regions, and determine the property of the sample by using a relationship between the first optical measurement, the second optical measurement, and the predefined height difference between the first selected region and the second selected region. determine a signal level of the biological sample, based upon the determined signal level, select two out of the first, second, and third regions upon which to perform, respectively, first and second optical measurements, receive data relating to the first optical measurement that is performed upon a portion of the sample that is disposed within a first one of the selected regions, receive data relating to a second optical measurement that is performed upon a portion of the sample that is disposed within a second one of the selected regions, and determine the property of the sample by using a relationship between the first optical measurement, the second optical measurement, and the predefined height difference between the first selected region and the second selected region. <EOS>