The Chevalier weren't satisfied: the lenses were too much thick and the focal length too long (37 mm); in particular they had an unfavourable arrangement, due to the convex side turned toward the specimen: this made necessary placing a small diaphragm on the upper lens, but this reduced the objective brightness and depth of field. Nevertheless, Selligue showed the microscope to the Academie Royale des Sciences on 5 April 1824; on 30 August of the same year Fresnel examined the instrument, noticed the problems, but compiled in any case a favourable report. Fresnel did not mention Vincent and Charles Chevalier in his report, because he didn't know they worked together with Selligue.
Charles realized a substantial improvement when, taking again the works by Euler in the field of optic, he used crown and flint glass, each pair consisting of a double-convex of crown glass and a plano-concave of flint, joined by Canada balm. In this way he didn't allow humidity to interpose between the two glasses and avoided light dispersion due to reflections on the opposite glass surfaces. This was a great improvement for the optical science and for microscopic observations, with new and important discoveries by this instrument. On 30 March 1825 Vincent and Charles presented an improved achromatic microscope to the Societe d'encouragement. In the report written by Hachette, he noticed as the instrument had not appreciable aberrations, showing the same sharpness of achromatic telescopes, the most excellent optical instruments of the time.

"Le microscope universel"
G. B. Amici resumed lens making in Italy in 1826 thanks to Fresnel's report and, on 25 May 1827, he arrived in Paris with a horizontal microscope that had three achromatic lenses superimposed, with a right-angled prism above them. The objectives of Chevalier, whose shop sign was "Au microscope acromatique", had been of this form, which is why this type is called "French buttons". Based on Amici's design, Chevalier and Selligue promptly began to make horizontal microscopes, with Amici's advice. This instrument was declared by Arago "perfectly realized" and awarded a silver medal. When this new instrument was exhibited at "L'Exposition des Produits de L'Industrie Nationale" in 1834, was awarded the Gold Medal; it had been made on a request by Savart, member of the College de France and of the Academie Royale des Sciences.