Biomedical assays

A method of performing a biomedical assay in which light is emitted by a sample or samples when excited by incident radiation in order to obtain an error corrected measurement signal, comprising the steps of:

• exciting the sample or samples along an excitation path with incident radiation of a given wavelength, thereby causing the sample to emit radiation of another wavelength transmitted along an emission path,
• measuring the quantity of light falling on a detector receiving the emitted radiation from the sample along the emission path, thereby to produce a first measurement,
• at a different time illuminating the sample or samples along the same excitation path with incident radiation of a different wavelength which does not cause the sample or samples to emit any significant radiation, wherein the light of different wavelength lies in the infra-red region,
• detecting the quantity of light transmitted along the same emission path to fall on the same detector, thereby to produce a second measurement, and
• correcting the first measurement with respect to the second measurement, whereby to correct the first measurement in respect of errors, including errors inherent in the measurement system.

A method of performing a biomedical assay in which light is emitted by a sample or samples when excited by incident radiation in order to obtain an error corrected measurement signal, comprising the steps of:

• exciting the sample or samples along an excitation path with incident radiation of a given wavelength, thereby causing the sample to emit radiation of another wavelength transmitted along an emission path,
• measuring the quantity of light falling on a detector receiving the emitted radiation from the sample along the emission path, thereby to produce a first measurement,
• at a different time illuminating the sample or samples along the same excitation path with incident radiation of a different wavelength which does not cause the sample or samples to emit any significant radiation, wherein the light of different wavelength lies in the ultraviolet region,
• detecting the quantity of light transmitted along the same emission path to fall on the same detector, thereby to produce a second measurement, and
• correcting the first measurement with respect to the second measurement, whereby to correct the first measurement in respect of errors, including errors inherent in the measurement system.

A method of performing a biomedical assay in which light is emitted by a sample or samples when excited by incident radiation in order to obtain an error corrected measurement signal, comprising the steps of:

• exciting the sample or samples along an excitation path with incident radiation of a given wavelength, thereby causing the sample to emit radiation of another wavelength transmitted along an emission path,
• measuring the quantity of light falling on a detector receiving the emitted radiation from the sample along the emission path, thereby to produce a first measurement,
• at a different time illuminating the sample or samples along the same excitation path with incident radiation of a different wavelength which does not cause the sample or samples to emit any significant radiation,
• detecting the quantity of light transmitted along the same emission path to fall on the same detector, thereby to produce a second measurement,
• correcting the first measurement with respect to the second measurement, whereby to correct the first measurement in respect of errors, including errors inherent in the measurement system, and
• wherein, when a multiple channel reading head reading a multiplicity of samples is employed, the first measurement is also corrected for variation in the stand-off of samples with respect to the reading head by averaging the first measurement over a plurality of the said multiplicity of samples.